# strutils

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The system module defines several common functions for working with strings, such as:

- `$` for converting other data-types to strings
- `&` for string concatenation
- `add` for adding a new character or a string to the existing one
- `in` (alias for `contains`) and `notin` for checking if a character is in a string

This module builds upon that, providing additional functionality in form of procedures, iterators and templates for strings.

    import strutils

    let
      numbers = @[867, 5309]
      multiLineString = "first line\nsecond line\nthird line"

    let jenny = numbers.join("-")
    assert jenny == "867-5309"

    assert splitLines(multiLineString) ==
           @["first line", "second line", "third line"]
    assert split(multiLineString) == @["first", "line", "second",
                                       "line", "third", "line"]
    assert indent(multiLineString, 4) ==
           "    first line\n    second line\n    third line"
    assert 'z'.repeat(5) == "zzzzz"

The chaining of functions is possible thanks to the method call syntax:

    import strutils
    from sequtils import map

    let jenny = "867-5309"
    assert jenny.split('-').map(parseInt) == @[867, 5309]

    assert "Beetlejuice".indent(1).repeat(3).strip ==
           "Beetlejuice Beetlejuice Beetlejuice"

This module is available for the JavaScript target.

See also:

- strformat module for string interpolation and formatting
- unicode module for Unicode UTF-8 handling
- sequtils module for operations on container types (including strings)
- parseutils module for lower-level parsing of tokens, numbers, identifiers, etc.
- parseopt module for command-line parsing
- strtabs module for efficient hash tables (dictionaries, in some programming languages) mapping from strings to strings
- pegs module for PEG (Parsing Expression Grammar) support
- ropes module for rope data type, which can represent very long strings efficiently
- re module for regular expression (regex) support
- strscans for `scanf` and `scanp` macros, which offer easier substring extraction than regular expressions

# Imports

parseutils, math, algorithm, unicode

# Types

    SkipTable = array[char, int]

  Source Edit

    FloatFormatMode = enum
      ffDefault,                  ## use the shorter floating point notation
      ffDecimal,                  ## use decimal floating point notation
      ffScientific                ## use scientific notation (using ``e`` character)

  the different modes of floating point formatting Source Edit

    BinaryPrefixMode = enum
      bpIEC, bpColloquial

  the different names for binary prefixes Source Edit

# Consts

    Whitespace = {' ', '\t', '\v', '\c', '\n', '\f'}

  All the characters that count as whitespace (space, tab, vertical tab, carriage return, new line, form feed) Source Edit

    Letters = {'A'..'Z', 'a'..'z'}

  the set of letters Source Edit

    Digits = {'0'..'9'}

  the set of digits Source Edit

    HexDigits = {'0'..'9', 'A'..'F', 'a'..'f'}

  the set of hexadecimal digits Source Edit

    IdentChars = {'a'..'z', 'A'..'Z', '0'..'9', '_'}

  the set of characters an identifier can consist of Source Edit

    IdentStartChars = {'a'..'z', 'A'..'Z', '_'}

  the set of characters an identifier can start with Source Edit

    Newlines = {'\c', '\n'}

  the set of characters a newline terminator can start with (carriage return, line feed) Source Edit

    AllChars = {'\x00'..'\xFF'}

  A set with all the possible characters.

  Not very useful by its own, you can use it to create inverted sets to make the find proc find invalid characters in strings. Example:

      let invalid = AllChars - Digits
      doAssert "01234".find(invalid) == -1
      doAssert "01A34".find(invalid) == 2

  Source Edit

# Procs

    proc isAlphaAscii(c: char): bool {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuIsAlphaAsciiChar", raises: [], tags: [].}

  Checks whether or not character `c` is alphabetical.

  This checks a-z, A-Z ASCII characters only. Use Unicode module for UTF-8 support.

  Examples:

      doAssert isAlphaAscii('e') == true
      doAssert isAlphaAscii('E') == true
      doAssert isAlphaAscii('8') == false

  Source Edit

    proc isAlphaNumeric(c: char): bool {...}{.noSideEffect, procvar, gcsafe,
                                     extern: "nsuIsAlphaNumericChar", raises: [],
                                     tags: [].}

  Checks whether or not `c` is alphanumeric.

  This checks a-z, A-Z, 0-9 ASCII characters only.

  Examples:

      doAssert isAlphaNumeric('n') == true
      doAssert isAlphaNumeric('8') == true
      doAssert isAlphaNumeric(' ') == false

  Source Edit

    proc isDigit(c: char): bool {...}{.noSideEffect, procvar, gcsafe, extern: "nsuIsDigitChar",
                              raises: [], tags: [].}

  Checks whether or not `c` is a number.

  This checks 0-9 ASCII characters only.

  Examples:

      doAssert isDigit('n') == false
      doAssert isDigit('8') == true

  Source Edit

    proc isSpaceAscii(c: char): bool {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuIsSpaceAsciiChar", raises: [], tags: [].}

  Checks whether or not `c` is a whitespace character.

  Examples:

      doAssert isSpaceAscii('n') == false
      doAssert isSpaceAscii(' ') == true
      doAssert isSpaceAscii('\t') == true

  Source Edit

    proc isLowerAscii(c: char): bool {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuIsLowerAsciiChar", raises: [], tags: [].}

  Checks whether or not `c` is a lower case character.

  This checks ASCII characters only. Use Unicode module for UTF-8 support.

  See also:

  - toLowerAscii proc

  Examples:

      doAssert isLowerAscii('e') == true
      doAssert isLowerAscii('E') == false
      doAssert isLowerAscii('7') == false

  Source Edit

    proc isUpperAscii(c: char): bool {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuIsUpperAsciiChar", raises: [], tags: [].}

  Checks whether or not `c` is an upper case character.

  This checks ASCII characters only. Use Unicode module for UTF-8 support.

  See also:

  - toUpperAscii proc

  Examples:

      doAssert isUpperAscii('e') == false
      doAssert isUpperAscii('E') == true
      doAssert isUpperAscii('7') == false

  Source Edit

    proc toLowerAscii(c: char): char {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuToLowerAsciiChar", raises: [], tags: [].}

  Returns the lower case version of character `c`.

  This works only for the letters `A-Z`. See unicode.toLower for a version that works for any Unicode character.

  See also:

  - isLowerAscii proc
  - toLowerAscii proc for converting a string

  Examples:

      doAssert toLowerAscii('A') == 'a'
      doAssert toLowerAscii('e') == 'e'

  Source Edit

    proc toLowerAscii(s: string): string {...}{.noSideEffect, procvar, gcsafe,
                                       extern: "nsuToLowerAsciiStr", raises: [],
                                       tags: [].}

  Converts string `s` into lower case.

  This works only for the letters `A-Z`. See unicode.toLower for a version that works for any Unicode character.

  See also:

  - normalize proc

  Examples:

      doAssert toLowerAscii("FooBar!") == "foobar!"

  Source Edit

    proc toUpperAscii(c: char): char {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuToUpperAsciiChar", raises: [], tags: [].}

  Converts character `c` into upper case.

  This works only for the letters `A-Z`. See unicode.toUpper for a version that works for any Unicode character.

  See also:

  - isLowerAscii proc
  - toUpperAscii proc for converting a string
  - capitalizeAscii proc

  Examples:

      doAssert toUpperAscii('a') == 'A'
      doAssert toUpperAscii('E') == 'E'

  Source Edit

    proc toUpperAscii(s: string): string {...}{.noSideEffect, procvar, gcsafe,
                                       extern: "nsuToUpperAsciiStr", raises: [],
                                       tags: [].}

  Converts string `s` into upper case.

  This works only for the letters `A-Z`. See unicode.toUpper for a version that works for any Unicode character.

  See also:

  - capitalizeAscii proc

  Examples:

      doAssert toUpperAscii("FooBar!") == "FOOBAR!"

  Source Edit

    proc capitalizeAscii(s: string): string {...}{.noSideEffect, procvar, gcsafe,
                                          extern: "nsuCapitalizeAscii", raises: [],
                                          tags: [].}

  Converts the first character of string `s` into upper case.

  This works only for the letters `A-Z`. Use Unicode module for UTF-8 support.

  See also:

  - toUpperAscii proc

  Examples:

      doAssert capitalizeAscii("foo") == "Foo"
      doAssert capitalizeAscii("-bar") == "-bar"

  Source Edit

    proc normalize(s: string): string {...}{.noSideEffect, procvar, gcsafe,
                                    extern: "nsuNormalize", raises: [], tags: [].}

  Normalizes the string `s`.

  That means to convert it to lower case and remove any '_'. This should NOT be used to normalize Nim identifier names.

  See also:

  - toLowerAscii proc

  Examples:

      doAssert normalize("Foo_bar") == "foobar"
      doAssert normalize("Foo Bar") == "foo bar"

  Source Edit

    proc cmpIgnoreCase(a, b: string): int {...}{.noSideEffect, gcsafe,
                                       extern: "nsuCmpIgnoreCase", procvar, raises: [],
                                       tags: [].}

  Compares two strings in a case insensitive manner. Returns:

  0 if a == b
  < 0 if a < b
  > 0 if a > b

  Examples:

      doAssert cmpIgnoreCase("FooBar", "foobar") == 0
      doAssert cmpIgnoreCase("bar", "Foo") < 0
      doAssert cmpIgnoreCase("Foo5", "foo4") > 0

  Source Edit

    proc cmpIgnoreStyle(a, b: string): int {...}{.noSideEffect, gcsafe,
                                        extern: "nsuCmpIgnoreStyle", procvar,
                                        raises: [], tags: [].}

  Semantically the same as `cmp(normalize(a), normalize(b))`. It is just optimized to not allocate temporary strings. This should NOT be used to compare Nim identifier names. Use macros.eqIdent for that.

  Returns:

  0 if a == b
  < 0 if a < b
  > 0 if a > b

  Examples:

      doAssert cmpIgnoreStyle("foo_bar", "FooBar") == 0
      doAssert cmpIgnoreStyle("foo_bar_5", "FooBar4") > 0

  Source Edit

    proc split(s: string; sep: char; maxsplit: int = -1): seq[string] {...}{.noSideEffect, gcsafe,
        extern: "nsuSplitChar", raises: [], tags: [].}

  The same as the split iterator (see its documentation), but is a proc that returns a sequence of substrings.

  See also:

  - split iterator
  - rsplit proc
  - splitLines proc
  - splitWhitespace proc

  Examples:

      doAssert "a,b,c".split(',') == @["a", "b", "c"]
      doAssert "".split(' ') == @[""]

  Source Edit

    proc split(s: string; seps: set[char] = Whitespace; maxsplit: int = -1): seq[string] {...}{.
        noSideEffect, gcsafe, extern: "nsuSplitCharSet", raises: [], tags: [].}

  The same as the split iterator (see its documentation), but is a proc that returns a sequence of substrings.

  See also:

  - split iterator
  - rsplit proc
  - splitLines proc
  - splitWhitespace proc

  Examples:

      doAssert "a,b;c".split({',', ';'}) == @["a", "b", "c"]
      doAssert "".split({' '}) == @[""]

  Source Edit

    proc split(s: string; sep: string; maxsplit: int = -1): seq[string] {...}{.noSideEffect, gcsafe,
        extern: "nsuSplitString", raises: [], tags: [].}

  Splits the string `s` into substrings using a string separator.

  Substrings are separated by the string `sep`. This is a wrapper around the split iterator.

  See also:

  - split iterator
  - rsplit proc
  - splitLines proc
  - splitWhitespace proc

  Examples:

      doAssert "a,b,c".split(",") == @["a", "b", "c"]
      doAssert "a man a plan a canal panama".split("a ") ==
          @["", "man ", "plan ", "canal panama"]
      doAssert "".split("Elon Musk") == @[""]
      doAssert "a  largely    spaced sentence".split(" ") ==
          @["a", "", "largely", "", "", "", "spaced", "sentence"]
      doAssert "a  largely    spaced sentence".split(" ", maxsplit = 1) ==
          @["a", " largely    spaced sentence"]

  Source Edit

    proc rsplit(s: string; sep: char; maxsplit: int = -1): seq[string] {...}{.noSideEffect, gcsafe,
        extern: "nsuRSplitChar", raises: [], tags: [].}

  The same as the rsplit iterator, but is a proc that returns a sequence of substrings.

  A possible common use case for `rsplit` is path manipulation, particularly on systems that don't use a common delimiter.

  For example, if a system had `#` as a delimiter, you could do the following to get the tail of the path:

      var tailSplit = rsplit("Root#Object#Method#Index", '#', maxsplit=1)

  Results in `tailSplit` containing:

      @["Root#Object#Method", "Index"]

  See also:

  - rsplit iterator
  - split proc
  - splitLines proc
  - splitWhitespace proc
  Source Edit

    proc rsplit(s: string; seps: set[char] = Whitespace; maxsplit: int = -1): seq[string] {...}{.
        noSideEffect, gcsafe, extern: "nsuRSplitCharSet", raises: [], tags: [].}

  The same as the rsplit iterator, but is a proc that returns a sequence of substrings.

  A possible common use case for `rsplit` is path manipulation, particularly on systems that don't use a common delimiter.

  For example, if a system had `#` as a delimiter, you could do the following to get the tail of the path:

      var tailSplit = rsplit("Root#Object#Method#Index", {'#'}, maxsplit=1)

  Results in `tailSplit` containing:

      @["Root#Object#Method", "Index"]

  See also:

  - rsplit iterator
  - split proc
  - splitLines proc
  - splitWhitespace proc
  Source Edit

    proc rsplit(s: string; sep: string; maxsplit: int = -1): seq[string] {...}{.noSideEffect,
        gcsafe, extern: "nsuRSplitString", raises: [], tags: [].}

  The same as the rsplit iterator, but is a proc that returns a sequence of substrings.

  A possible common use case for `rsplit` is path manipulation, particularly on systems that don't use a common delimiter.

  For example, if a system had `#` as a delimiter, you could do the following to get the tail of the path:

      var tailSplit = rsplit("Root#Object#Method#Index", "#", maxsplit=1)

  Results in `tailSplit` containing:

      @["Root#Object#Method", "Index"]

  See also:

  - rsplit iterator
  - split proc
  - splitLines proc
  - splitWhitespace proc

  Examples:

      doAssert "a  largely    spaced sentence".rsplit(" ", maxsplit = 1) ==
          @["a  largely    spaced", "sentence"]
      doAssert "a,b,c".rsplit(",") == @["a", "b", "c"]
      doAssert "a man a plan a canal panama".rsplit("a ") ==
          @["", "man ", "plan ", "canal panama"]
      doAssert "".rsplit("Elon Musk") == @[""]
      doAssert "a  largely    spaced sentence".rsplit(" ") ==
          @["a", "", "largely", "", "", "", "spaced", "sentence"]

  Source Edit

    proc splitLines(s: string; keepEol = false): seq[string] {...}{.noSideEffect, gcsafe,
        extern: "nsuSplitLines", raises: [], tags: [].}

  The same as the splitLines iterator (see its documentation), but is a proc that returns a sequence of substrings.

  See also:

  - splitLines iterator
  - splitWhitespace proc
  - countLines proc
  Source Edit

    proc splitWhitespace(s: string; maxsplit: int = -1): seq[string] {...}{.noSideEffect, gcsafe,
        extern: "nsuSplitWhitespace", raises: [], tags: [].}

  The same as the splitWhitespace iterator (see its documentation), but is a proc that returns a sequence of substrings.

  See also:

  - splitWhitespace iterator
  - splitLines proc
  Source Edit

    proc toBin(x: BiggestInt; len: Positive): string {...}{.noSideEffect, gcsafe,
        extern: "nsuToBin", raises: [], tags: [].}

  Converts `x` into its binary representation.

  The resulting string is always `len` characters long. No leading `0b` prefix is generated.

  Examples:

      let
        a = 29
        b = 257
      doAssert a.toBin(8) == "00011101"
      doAssert b.toBin(8) == "00000001"
      doAssert b.toBin(9) == "100000001"

  Source Edit

    proc toOct(x: BiggestInt; len: Positive): string {...}{.noSideEffect, gcsafe,
        extern: "nsuToOct", raises: [], tags: [].}

  Converts `x` into its octal representation.

  The resulting string is always `len` characters long. No leading `0o` prefix is generated.

  Do not confuse it with toOctal proc.

  Examples:

      let
        a = 62
        b = 513
      doAssert a.toOct(3) == "076"
      doAssert b.toOct(3) == "001"
      doAssert b.toOct(5) == "01001"

  Source Edit

    proc toHex(x: BiggestInt; len: Positive): string {...}{.noSideEffect, gcsafe,
        extern: "nsuToHex", raises: [], tags: [].}

  Converts `x` to its hexadecimal representation.

  The resulting string will be exactly `len` characters long. No prefix like `0x` is generated. `x` is treated as an unsigned value.

  Examples:

      let
        a = 62
        b = 4097
      doAssert a.toHex(3) == "03E"
      doAssert b.toHex(3) == "001"
      doAssert b.toHex(4) == "1001"

  Source Edit

    proc toHex[T: SomeInteger](x: T): string

  Shortcut for `toHex(x, T.sizeOf * 2)`

  Examples:

      doAssert toHex(1984'i64) == "00000000000007C0"

  Source Edit

    proc toHex(s: string): string {...}{.noSideEffect, gcsafe, raises: [], tags: [].}

  Converts a bytes string to its hexadecimal representation.

  The output is twice the input long. No prefix like `0x` is generated.

  See also:

  - parseHexStr proc for the reverse operation

  Examples:

      let
        a = "1"
        b = "A"
        c = "\x00ÿ"
      doAssert a.toHex() == "31"
      doAssert b.toHex() == "41"
      doAssert c.toHex() == "00FF"

  Source Edit

    proc toOctal(c: char): string {...}{.noSideEffect, gcsafe, extern: "nsuToOctal", raises: [],
                                tags: [].}

  Converts a character `c` to its octal representation.

  The resulting string may not have a leading zero. Its length is always exactly 3.

  Do not confuse it with toOct proc.

  Examples:

      doAssert toOctal('1') == "061"
      doAssert toOctal('A') == "101"
      doAssert toOctal('a') == "141"
      doAssert toOctal('!') == "041"

  Source Edit

    proc fromBin[T: SomeInteger](s: string): T

  Parses a binary integer value from a string `s`.

  If `s` is not a valid binary integer, `ValueError` is raised. `s` can have one of the following optional prefixes: `0b`, `0B`. Underscores within `s` are ignored.

  Does not check for overflow. If the value represented by `s` is too big to fit into a return type, only the value of the rightmost binary digits of `s` is returned without producing an error.

  Examples:

      let s = "0b_0100_1000_1000_1000_1110_1110_1001_1001"
      doAssert fromBin[int](s) == 1216933529
      doAssert fromBin[int8](s) == 0b10011001'i8
      doAssert fromBin[int8](s) == -103'i8
      doAssert fromBin[uint8](s) == 153
      doAssert fromBin[int16](s) == 0b1110111010011001'i16
      doAssert fromBin[uint64](s) == 1216933529'u64

  Source Edit

    proc fromOct[T: SomeInteger](s: string): T

  Parses an octal integer value from a string `s`.

  If `s` is not a valid octal integer, `ValueError` is raised. `s` can have one of the following optional prefixes: `0o`, `0O`. Underscores within `s` are ignored.

  Does not check for overflow. If the value represented by `s` is too big to fit into a return type, only the value of the rightmost octal digits of `s` is returned without producing an error.

  Examples:

      let s = "0o_123_456_777"
      doAssert fromOct[int](s) == 21913087
      doAssert fromOct[int8](s) == 0o377'i8
      doAssert fromOct[int8](s) == -1'i8
      doAssert fromOct[uint8](s) == 255'u8
      doAssert fromOct[int16](s) == 24063'i16
      doAssert fromOct[uint64](s) == 21913087'u64

  Source Edit

    proc fromHex[T: SomeInteger](s: string): T

  Parses a hex integer value from a string `s`.

  If `s` is not a valid hex integer, `ValueError` is raised. `s` can have one of the following optional prefixes: `0x`, `0X`, `#`. Underscores within `s` are ignored.

  Does not check for overflow. If the value represented by `s` is too big to fit into a return type, only the value of the rightmost hex digits of `s` is returned without producing an error.

  Examples:

      let s = "0x_1235_8df6"
      doAssert fromHex[int](s) == 305499638
      doAssert fromHex[int8](s) == 0xF6'i8
      doAssert fromHex[int8](s) == -10'i8
      doAssert fromHex[uint8](s) == 246'u8
      doAssert fromHex[int16](s) == -29194'i16
      doAssert fromHex[uint64](s) == 305499638'u64

  Source Edit

    proc intToStr(x: int; minchars: Positive = 1): string {...}{.noSideEffect, gcsafe,
        extern: "nsuIntToStr", raises: [], tags: [].}

  Converts `x` to its decimal representation.

  The resulting string will be minimally `minchars` characters long. This is achieved by adding leading zeros.

  Examples:

      doAssert intToStr(1984) == "1984"
      doAssert intToStr(1984, 6) == "001984"

  Source Edit

    proc parseInt(s: string): int {...}{.noSideEffect, procvar, gcsafe, extern: "nsuParseInt",
                                raises: [ValueError], tags: [].}

  Parses a decimal integer value contained in `s`.

  If `s` is not a valid integer, `ValueError` is raised.

  Examples:

      doAssert parseInt("-0042") == -42

  Source Edit

    proc parseBiggestInt(s: string): BiggestInt {...}{.noSideEffect, procvar, gcsafe,
        extern: "nsuParseBiggestInt", raises: [ValueError], tags: [].}

  Parses a decimal integer value contained in `s`.

  If `s` is not a valid integer, `ValueError` is raised.

  Source Edit

    proc parseUInt(s: string): uint {...}{.noSideEffect, procvar, gcsafe,
                                  extern: "nsuParseUInt", raises: [ValueError], tags: [].}

  Parses a decimal unsigned integer value contained in `s`.

  If `s` is not a valid integer, `ValueError` is raised.

  Source Edit

    proc parseBiggestUInt(s: string): BiggestUInt {...}{.noSideEffect, procvar, gcsafe,
        extern: "nsuParseBiggestUInt", raises: [ValueError], tags: [].}

  Parses a decimal unsigned integer value contained in `s`.

  If `s` is not a valid integer, `ValueError` is raised.

  Source Edit

    proc parseFloat(s: string): float {...}{.noSideEffect, procvar, gcsafe,
                                    extern: "nsuParseFloat", raises: [ValueError],
                                    tags: [].}

  Parses a decimal floating point value contained in `s`.

  If `s` is not a valid floating point number, `ValueError` is raised. `NAN`, `INF`, `-INF` are also supported (case insensitive comparison).

  Examples:

      doAssert parseFloat("3.14") == 3.14
      doAssert parseFloat("inf") == 1.0 / 0

  Source Edit

    proc parseBinInt(s: string): int {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuParseBinInt", raises: [ValueError],
                                   tags: [].}

  Parses a binary integer value contained in `s`.

  If `s` is not a valid binary integer, `ValueError` is raised. `s` can have one of the following optional prefixes: `0b`, `0B`. Underscores within `s` are ignored.

  Examples:

      let
        a = "0b11_0101"
        b = "111"
      doAssert a.parseBinInt() == 53
      doAssert b.parseBinInt() == 7

  Source Edit

    proc parseOctInt(s: string): int {...}{.noSideEffect, gcsafe, extern: "nsuParseOctInt",
                                   raises: [ValueError], tags: [].}

  Parses an octal integer value contained in `s`.

  If `s` is not a valid oct integer, `ValueError` is raised. `s` can have one of the following optional prefixes: `0o`, `0O`. Underscores within `s` are ignored.

  Source Edit

    proc parseHexInt(s: string): int {...}{.noSideEffect, procvar, gcsafe,
                                   extern: "nsuParseHexInt", raises: [ValueError],
                                   tags: [].}

  Parses a hexadecimal integer value contained in `s`.

  If `s` is not a valid hex integer, `ValueError` is raised. `s` can have one of the following optional prefixes: `0x`, `0X`, `#`. Underscores within `s` are ignored.

  Source Edit

    proc parseHexStr(s: string): string {...}{.noSideEffect, procvar, gcsafe,
                                      extern: "nsuParseHexStr", raises: [ValueError],
                                      tags: [].}

  Convert hex-encoded string to byte string, e.g.:

  Raises `ValueError` for an invalid hex values. The comparison is case-insensitive.

  See also:

  - toHex proc for the reverse operation

  Examples:

      let
        a = "41"
        b = "3161"
        c = "00ff"
      doAssert parseHexStr(a) == "A"
      doAssert parseHexStr(b) == "1a"
      doAssert parseHexStr(c) == "\x00ÿ"

  Source Edit

    proc parseBool(s: string): bool {...}{.raises: [ValueError], tags: [].}

  Parses a value into a `bool`.

  If `s` is one of the following values: `y, yes, true, 1, on`, then returns `true`. If `s` is one of the following values: `n, no, false, 0, off`, then returns `false`. If `s` is something else a `ValueError` exception is raised.

  Examples:

      let a = "n"
      doAssert parseBool(a) == false

  Source Edit

    proc parseEnum[T: enum](s: string): T

  Parses an enum `T`.

  Raises `ValueError` for an invalid value in `s`. The comparison is done in a style insensitive way.

  Examples:

      type
        MyEnum = enum
          first = "1st", second, third = "3rd"
      doAssert parseEnum[MyEnum]("1_st") == first
      doAssert parseEnum[MyEnum]("second") == second
      doAssertRaises(ValueError):
        echo parseEnum[MyEnum]("third")

  Source Edit

    proc parseEnum[T: enum](s: string; default: T): T

  Parses an enum `T`.

  Uses `default` for an invalid value in `s`. The comparison is done in a style insensitive way.

  Examples:

      type
        MyEnum = enum
          first = "1st", second, third = "3rd"
      doAssert parseEnum[MyEnum]("1_st") == first
      doAssert parseEnum[MyEnum]("second") == second
      doAssert parseEnum[MyEnum]("last", third) == third

  Source Edit

    proc repeat(c: char; count: Natural): string {...}{.noSideEffect, gcsafe,
        extern: "nsuRepeatChar", raises: [], tags: [].}

  Returns a string of length `count` consisting only of the character `c`.

  Examples:

      let a = 'z'
      doAssert a.repeat(5) == "zzzzz"

  Source Edit

    proc repeat(s: string; n: Natural): string {...}{.noSideEffect, gcsafe,
                                           extern: "nsuRepeatStr", raises: [], tags: [].}

  Returns string `s` concatenated `n` times.

  Examples:

      doAssert "+ foo +".repeat(3) == "+ foo ++ foo ++ foo +"

  Source Edit

    proc spaces(n: Natural): string {...}{.inline, raises: [], tags: [].}

  Returns a string with `n` space characters. You can use this proc to left align strings.

  See also:

  - align proc
  - alignLeft proc
  - indent proc
  - center proc

  Examples:

      let
        width = 15
        text1 = "Hello user!"
        text2 = "This is a very long string"
      doAssert text1 & spaces(max(0, width - text1.len)) & "|" == "Hello user!    |"
      doAssert text2 & spaces(max(0, width - text2.len)) & "|" ==
          "This is a very long string|"

  Source Edit

    proc align(s: string; count: Natural; padding = ' '): string {...}{.noSideEffect, gcsafe,
        extern: "nsuAlignString", raises: [], tags: [].}

  Aligns a string `s` with `padding`, so that it is of length `count`.

  `padding` characters (by default spaces) are added before `s` resulting in right alignment. If `s.len >= count`, no spaces are added and `s` is returned unchanged. If you need to left align a string use the alignLeft proc.

  See also:

  - alignLeft proc
  - spaces proc
  - indent proc
  - center proc

  Examples:

      assert align("abc", 4) == " abc"
      assert align("a", 0) == "a"
      assert align("1232", 6) == "  1232"
      assert align("1232", 6, '#') == "##1232"

  Source Edit

    proc alignLeft(s: string; count: Natural; padding = ' '): string {...}{.noSideEffect,
        raises: [], tags: [].}

  Left-Aligns a string `s` with `padding`, so that it is of length `count`.

  `padding` characters (by default spaces) are added after `s` resulting in left alignment. If `s.len >= count`, no spaces are added and `s` is returned unchanged. If you need to right align a string use the align proc.

  See also:

  - align proc
  - spaces proc
  - indent proc
  - center proc

  Examples:

      assert alignLeft("abc", 4) == "abc "
      assert alignLeft("a", 0) == "a"
      assert alignLeft("1232", 6) == "1232  "
      assert alignLeft("1232", 6, '#') == "1232##"

  Source Edit

    proc center(s: string; width: int; fillChar: char = ' '): string {...}{.noSideEffect, gcsafe,
        extern: "nsuCenterString", raises: [], tags: [].}

  Return the contents of `s` centered in a string `width` long using `fillChar` (default: space) as padding.

  The original string is returned if `width` is less than or equal to `s.len`.

  See also:

  - align proc
  - alignLeft proc
  - spaces proc
  - indent proc

  Examples:

      let a = "foo"
      doAssert a.center(2) == "foo"
      doAssert a.center(5) == " foo "
      doAssert a.center(6) == " foo  "

  Source Edit

    proc indent(s: string; count: Natural; padding: string = " "): string {...}{.noSideEffect,
        gcsafe, extern: "nsuIndent", raises: [], tags: [].}

  Indents each line in `s` by `count` amount of `padding`.

  Note: This does not preserve the new line characters used in `s`.

  See also:

  - align proc
  - alignLeft proc
  - spaces proc
  - unindent proc

  Examples:

      doAssert indent("First line\c\n and second line.", 2) ==
          "  First line\n   and second line."

  Source Edit

    proc unindent(s: string; count: Natural; padding: string = " "): string {...}{.noSideEffect,
        gcsafe, extern: "nsuUnindent", raises: [], tags: [].}

  Unindents each line in `s` by `count` amount of `padding`. Sometimes called dedent

  Note: This does not preserve the new line characters used in `s`.

  See also:

  - align proc
  - alignLeft proc
  - spaces proc
  - indent proc

  Examples:

      doAssert unindent("  First line\n   and second line", 3) ==
          "First line\nand second line"

  Source Edit

    proc unindent(s: string): string {...}{.noSideEffect, gcsafe, extern: "nsuUnindentAll",
                                   raises: [], tags: [].}

  Removes all indentation composed of whitespace from each line in `s`.

  See also:

  - align proc
  - alignLeft proc
  - spaces proc
  - indent proc

  Examples:

      let x = """      Hello
            There
          """.unindent()
      doAssert x == "Hello\nThere\n"

  Source Edit

    proc delete(s: var string; first, last: int) {...}{.noSideEffect, gcsafe, extern: "nsuDelete",
                                            raises: [], tags: [].}

  Deletes in `s` (must be declared as `var`) the characters at positions `first ..last` (both ends included).

  This modifies `s` itself, it does not return a copy.

  Examples:

      var a = "abracadabra"
      a.delete(4, 5)
      doAssert a == "abradabra"
      a.delete(1, 6)
      doAssert a == "ara"
      a.delete(2, 999)
      doAssert a == "ar"

  Source Edit

    proc startsWith(s: string; prefix: char): bool {...}{.noSideEffect, inline, raises: [],
        tags: [].}

  Returns true if `s` starts with character `prefix`.

  See also:

  - endsWith proc
  - continuesWith proc
  - removePrefix proc

  Examples:

      let a = "abracadabra"
      doAssert a.startsWith('a') == true
      doAssert a.startsWith('b') == false

  Source Edit

    proc startsWith(s, prefix: string): bool {...}{.noSideEffect, gcsafe,
                                          extern: "nsuStartsWith", raises: [], tags: [].}

  Returns true if `s` starts with string `prefix`.

  If `prefix == ""` true is returned.

  See also:

  - endsWith proc
  - continuesWith proc
  - removePrefix proc

  Examples:

      let a = "abracadabra"
      doAssert a.startsWith("abra") == true
      doAssert a.startsWith("bra") == false

  Source Edit

    proc endsWith(s: string; suffix: char): bool {...}{.noSideEffect, inline, raises: [], tags: [].}

  Returns true if `s` ends with `suffix`.

  See also:

  - startsWith proc
  - continuesWith proc
  - removeSuffix proc

  Examples:

      let a = "abracadabra"
      doAssert a.endsWith('a') == true
      doAssert a.endsWith('b') == false

  Source Edit

    proc endsWith(s, suffix: string): bool {...}{.noSideEffect, gcsafe, extern: "nsuEndsWith",
                                        raises: [], tags: [].}

  Returns true if `s` ends with `suffix`.

  If `suffix == ""` true is returned.

  See also:

  - startsWith proc
  - continuesWith proc
  - removeSuffix proc

  Examples:

      let a = "abracadabra"
      doAssert a.endsWith("abra") == true
      doAssert a.endsWith("dab") == false

  Source Edit

    proc continuesWith(s, substr: string; start: Natural): bool {...}{.noSideEffect, gcsafe,
        extern: "nsuContinuesWith", raises: [], tags: [].}

  Returns true if `s` continues with `substr` at position `start`.

  If `substr == ""` true is returned.

  See also:

  - startsWith proc
  - endsWith proc

  Examples:

      let a = "abracadabra"
      doAssert a.continuesWith("ca", 4) == true
      doAssert a.continuesWith("ca", 5) == false
      doAssert a.continuesWith("dab", 6) == true

  Source Edit

    proc removePrefix(s: var string; chars: set[char] = Newlines) {...}{.gcsafe,
        extern: "nsuRemovePrefixCharSet", raises: [], tags: [].}

  Removes all characters from `chars` from the start of the string `s` (in-place).

  See also:

  - removeSuffix proc

  Examples:

      var userInput = "\c\n*~Hello World!"
      userInput.removePrefix
      doAssert userInput == "*~Hello World!"
      userInput.removePrefix({'~', '*'})
      doAssert userInput == "Hello World!"
      var otherInput = "?!?Hello!?!"
      otherInput.removePrefix({'!', '?'})
      doAssert otherInput == "Hello!?!"

  Source Edit

    proc removePrefix(s: var string; c: char) {...}{.gcsafe, extern: "nsuRemovePrefixChar",
                                          raises: [], tags: [].}

  Removes all occurrences of a single character (in-place) from the start of a string.

  See also:

  - removeSuffix proc
  - startsWith proc

  Examples:

      var ident = "pControl"
      ident.removePrefix('p')
      doAssert ident == "Control"

  Source Edit

    proc removePrefix(s: var string; prefix: string) {...}{.gcsafe,
        extern: "nsuRemovePrefixString", raises: [], tags: [].}

  Remove the first matching prefix (in-place) from a string.

  See also:

  - removeSuffix proc
  - startsWith proc

  Examples:

      var answers = "yesyes"
      answers.removePrefix("yes")
      doAssert answers == "yes"

  Source Edit

    proc removeSuffix(s: var string; chars: set[char] = Newlines) {...}{.gcsafe,
        extern: "nsuRemoveSuffixCharSet", raises: [], tags: [].}

  Removes all characters from `chars` from the end of the string `s` (in-place).

  See also:

  - removePrefix proc

  Examples:

      var userInput = "Hello World!*~\c\n"
      userInput.removeSuffix
      doAssert userInput == "Hello World!*~"
      userInput.removeSuffix({'~', '*'})
      doAssert userInput == "Hello World!"
      var otherInput = "Hello!?!"
      otherInput.removeSuffix({'!', '?'})
      doAssert otherInput == "Hello"

  Source Edit

    proc removeSuffix(s: var string; c: char) {...}{.gcsafe, extern: "nsuRemoveSuffixChar",
                                          raises: [], tags: [].}

  Removes all occurrences of a single character (in-place) from the end of a string.

  See also:

  - removePrefix proc
  - endsWith proc

  Examples:

      var table = "users"
      table.removeSuffix('s')
      doAssert table == "user"
      var dots = "Trailing dots......."
      dots.removeSuffix('.')
      doAssert dots == "Trailing dots"

  Source Edit

    proc removeSuffix(s: var string; suffix: string) {...}{.gcsafe,
        extern: "nsuRemoveSuffixString", raises: [], tags: [].}

  Remove the first matching suffix (in-place) from a string.

  See also:

  - removePrefix proc
  - endsWith proc

  Examples:

      var answers = "yeses"
      answers.removeSuffix("es")
      doAssert answers == "yes"

  Source Edit

    proc addSep(dest: var string; sep = ", "; startLen: Natural = 0) {...}{.noSideEffect, inline,
        raises: [], tags: [].}

  Adds a separator to `dest` only if its length is bigger than `startLen`.

  A shorthand for:

      if dest.len > startLen: add(dest, sep)

  This is often useful for generating some code where the items need to be separated by `sep`. `sep` is only added if `dest` is longer than `startLen`. The following example creates a string describing an array of integers.

  Examples:

      var arr = "["
      for x in items([2, 3, 5, 7, 11]):
        addSep(arr, startLen = len("["))
        add(arr, $x)
      add(arr, "]")
      doAssert arr == "[2, 3, 5, 7, 11]"

  Source Edit

    proc allCharsInSet(s: string; theSet: set[char]): bool {...}{.raises: [], tags: [].}

  Returns true if every character of `s` is in the set `theSet`.

  Examples:

      doAssert allCharsInSet("aeea", {'a', 'e'}) == true
      doAssert allCharsInSet("", {'a', 'e'}) == true

  Source Edit

    proc abbrev(s: string; possibilities: openArray[string]): int {...}{.raises: [], tags: [].}

  Returns the index of the first item in `possibilities` which starts with `s`, if not ambiguous.

  Returns -1 if no item has been found and -2 if multiple items match.

  Examples:

      doAssert abbrev("fac", ["college", "faculty", "industry"]) == 1
      doAssert abbrev("foo", ["college", "faculty", "industry"]) == -1
      doAssert abbrev("fac", ["college", "faculty", "faculties"]) == -2
      doAssert abbrev("college", ["college", "colleges", "industry"]) == 0

  Source Edit

    proc join(a: openArray[string]; sep: string = ""): string {...}{.noSideEffect, gcsafe,
        extern: "nsuJoinSep", raises: [], tags: [].}

  Concatenates all strings in the container `a`, separating them with `sep`.

  Examples:

      doAssert join(["A", "B", "Conclusion"], " -> ") == "A -> B -> Conclusion"

  Source Edit

    proc join[T: not string](a: openArray[T]; sep: string = ""): string {...}{.noSideEffect, gcsafe.}

  Converts all elements in the container `a` to strings using `$`, and concatenates them with `sep`.

  Examples:

      doAssert join([1, 2, 3], " -> ") == "1 -> 2 -> 3"

  Source Edit

    proc initSkipTable(a: var SkipTable; sub: string) {...}{.noSideEffect, gcsafe,
        extern: "nsuInitSkipTable", raises: [], tags: [].}

  Preprocess table `a` for `sub`. Source Edit

    proc find(a: SkipTable; s, sub: string; start: Natural = 0; last = 0): int {...}{.noSideEffect,
        gcsafe, extern: "nsuFindStrA", raises: [], tags: [].}

  Searches for `sub` in `s` inside range `start`..`last` using preprocessed table `a`. If `last` is unspecified, it defaults to `s.high` (the last element).

  Searching is case-sensitive. If `sub` is not in `s`, -1 is returned.

  Source Edit

    proc find(s: string; sub: char; start: Natural = 0; last = 0): int {...}{.noSideEffect, gcsafe,
        extern: "nsuFindChar", raises: [], tags: [].}

  Searches for `sub` in `s` inside range `start..last` (both ends included). If `last` is unspecified, it defaults to `s.high` (the last element).

  Searching is case-sensitive. If `sub` is not in `s`, -1 is returned. Otherwise the index returned is relative to `s[0]`, not `start`. Use `s[start..last].rfind` for a `start`-origin index.

  See also:

  - rfind proc
  - replace proc
  Source Edit

    proc find(s: string; chars: set[char]; start: Natural = 0; last = 0): int {...}{.noSideEffect,
        gcsafe, extern: "nsuFindCharSet", raises: [], tags: [].}

  Searches for `chars` in `s` inside range `start..last` (both ends included). If `last` is unspecified, it defaults to `s.high` (the last element).

  If `s` contains none of the characters in `chars`, -1 is returned. Otherwise the index returned is relative to `s[0]`, not `start`. Use `s[start..last].find` for a `start`-origin index.

  See also:

  - rfind proc
  - multiReplace proc
  Source Edit

    proc find(s, sub: string; start: Natural = 0; last = 0): int {...}{.noSideEffect, gcsafe,
        extern: "nsuFindStr", raises: [], tags: [].}

  Searches for `sub` in `s` inside range `start..last` (both ends included). If `last` is unspecified, it defaults to `s.high` (the last element).

  Searching is case-sensitive. If `sub` is not in `s`, -1 is returned. Otherwise the index returned is relative to `s[0]`, not `start`. Use `s[start..last].find` for a `start`-origin index.

  See also:

  - rfind proc
  - replace proc
  Source Edit

    proc rfind(s: string; sub: char; start: Natural = 0; last = -1): int {...}{.noSideEffect, gcsafe,
        extern: "nsuRFindChar", raises: [], tags: [].}

  Searches for `sub` in `s` inside range `start..last` (both ends included) in reverse -- starting at high indexes and moving lower to the first character or `start`. If `last` is unspecified, it defaults to `s.high` (the last element).

  Searching is case-sensitive. If `sub` is not in `s`, -1 is returned. Otherwise the index returned is relative to `s[0]`, not `start`. Use `s[start..last].find` for a `start`-origin index.

  See also:

  - find proc
  Source Edit

    proc rfind(s: string; chars: set[char]; start: Natural = 0; last = -1): int {...}{.noSideEffect,
        gcsafe, extern: "nsuRFindCharSet", raises: [], tags: [].}

  Searches for `chars` in `s` inside range `start..last` (both ends included) in reverse -- starting at high indexes and moving lower to the first character or `start`. If `last` is unspecified, it defaults to `s.high` (the last element).

  If `s` contains none of the characters in `chars`, -1 is returned. Otherwise the index returned is relative to `s[0]`, not `start`. Use `s[start..last].rfind` for a `start`-origin index.

  See also:

  - find proc
  Source Edit

    proc rfind(s, sub: string; start: Natural = 0; last = -1): int {...}{.noSideEffect, gcsafe,
        extern: "nsuRFindStr", raises: [], tags: [].}

  Searches for `sub` in `s` inside range `start..last` (both ends included) included) in reverse -- starting at high indexes and moving lower to the first character or `start`. If `last` is unspecified, it defaults to `s.high` (the last element).

  Searching is case-sensitive. If `sub` is not in `s`, -1 is returned. Otherwise the index returned is relative to `s[0]`, not `start`. Use `s[start..last].rfind` for a `start`-origin index.

  See also:

  - find proc
  Source Edit

    proc count(s: string; sub: char): int {...}{.noSideEffect, gcsafe, extern: "nsuCountChar",
                                      raises: [], tags: [].}

  Count the occurrences of the character `sub` in the string `s`.

  See also:

  - countLines proc
  Source Edit

    proc count(s: string; subs: set[char]): int {...}{.noSideEffect, gcsafe,
                                            extern: "nsuCountCharSet", raises: [],
                                            tags: [].}

  Count the occurrences of the group of character `subs` in the string `s`.

  See also:

  - countLines proc
  Source Edit

    proc count(s: string; sub: string; overlapping: bool = false): int {...}{.noSideEffect, gcsafe,
        extern: "nsuCountString", raises: [], tags: [].}

  Count the occurrences of a substring `sub` in the string `s`. Overlapping occurrences of `sub` only count when `overlapping` is set to true (default: false).

  See also:

  - countLines proc
  Source Edit

    proc countLines(s: string): int {...}{.noSideEffect, gcsafe, extern: "nsuCountLines",
                                  raises: [], tags: [].}

  Returns the number of lines in the string `s`.

  This is the same as `len(splitLines(s))`, but much more efficient because it doesn't modify the string creating temporal objects. Every character literal newline combination (CR, LF, CR-LF) is supported.

  In this context, a line is any string separated by a newline combination. A line can be an empty string.

  See also:

  - splitLines proc

  Examples:

      doAssert countLines("First line\n and second line.") == 2

  Source Edit

    proc contains(s, sub: string): bool {...}{.noSideEffect, raises: [], tags: [].}

  Same as `find(s, sub) >= 0`.

  See also:

  - find proc
  Source Edit

    proc contains(s: string; chars: set[char]): bool {...}{.noSideEffect, raises: [], tags: [].}

  Same as `find(s, chars) >= 0`.

  See also:

  - find proc
  Source Edit

    proc replace(s, sub: string; by = ""): string {...}{.noSideEffect, gcsafe,
                                            extern: "nsuReplaceStr", raises: [],
                                            tags: [].}

  Replaces `sub` in `s` by the string `by`.

  See also:

  - find proc
  - replace proc for replacing single characters
  - replaceWord proc
  - multiReplace proc
  Source Edit

    proc replace(s: string; sub, by: char): string {...}{.noSideEffect, gcsafe,
        extern: "nsuReplaceChar", raises: [], tags: [].}

  Replaces `sub` in `s` by the character `by`.

  Optimized version of replace for characters.

  See also:

  - find proc
  - replaceWord proc
  - multiReplace proc
  Source Edit

    proc replaceWord(s, sub: string; by = ""): string {...}{.noSideEffect, gcsafe,
        extern: "nsuReplaceWord", raises: [], tags: [].}

  Replaces `sub` in `s` by the string `by`.

  Each occurrence of `sub` has to be surrounded by word boundaries (comparable to `\b` in regular expressions), otherwise it is not replaced.

  Source Edit

    proc multiReplace(s: string; replacements: varargs[(string, string)]): string {...}{.
        noSideEffect, raises: [], tags: [].}

  Same as replace, but specialized for doing multiple replacements in a single pass through the input string.

  `multiReplace` performs all replacements in a single pass, this means it can be used to swap the occurrences of "a" and "b", for instance.

  If the resulting string is not longer than the original input string, only a single memory allocation is required.

  The order of the replacements does matter. Earlier replacements are preferred over later replacements in the argument list.

  Source Edit

    proc insertSep(s: string; sep = '_'; digits = 3): string {...}{.noSideEffect, gcsafe,
        extern: "nsuInsertSep", raises: [], tags: [].}

  Inserts the separator `sep` after `digits` characters (default: 3) from right to left.

  Even though the algorithm works with any string `s`, it is only useful if `s` contains a number.

  Examples:

      doAssert insertSep("1000000") == "1_000_000"

  Source Edit

    proc escape(s: string; prefix = "\""; suffix = "\""): string {...}{.noSideEffect, gcsafe,
        extern: "nsuEscape", raises: [], tags: [].}

  Escapes a string `s`. See system.addEscapedChar for the escaping scheme.

  The resulting string is prefixed with `prefix` and suffixed with `suffix`. Both may be empty strings.

  See also:

  - unescape proc for the opposite

  operation

  Source Edit

    proc unescape(s: string; prefix = "\""; suffix = "\""): string {...}{.noSideEffect, gcsafe,
        extern: "nsuUnescape", raises: [ValueError], tags: [].}

  Unescapes a string `s`.

  This complements escape proc as it performs the opposite operations.

  If `s` does not begin with `prefix` and end with `suffix` a ValueError exception will be raised.

  Source Edit

    proc validIdentifier(s: string): bool {...}{.noSideEffect, gcsafe,
                                        extern: "nsuValidIdentifier", raises: [],
                                        tags: [].}

  Returns true if `s` is a valid identifier.

  A valid identifier starts with a character of the set `IdentStartChars` and is followed by any number of characters of the set `IdentChars`.

  Examples:

      doAssert "abc_def08".validIdentifier

  Source Edit

    proc formatBiggestFloat(f: BiggestFloat; format: FloatFormatMode = ffDefault;
                           precision: range[-1 .. 32] = 16; decimalSep = '.'): string {...}{.
        noSideEffect, gcsafe, extern: "nsu$1", raises: [], tags: [].}

  Converts a floating point value `f` to a string.

  If `format == ffDecimal` then precision is the number of digits to be printed after the decimal point. If `format == ffScientific` then precision is the maximum number of significant digits to be printed. `precision`'s default value is the maximum number of meaningful digits after the decimal point for Nim's `biggestFloat` type.

  If `precision == -1`, it tries to format it nicely.

  Examples:

      let x = 123.456
      doAssert x.formatBiggestFloat() == "123.4560000000000"
      doAssert x.formatBiggestFloat(ffDecimal, 4) == "123.4560"
      doAssert x.formatBiggestFloat(ffScientific, 2) == "1.23e+02"

  Source Edit

    proc formatFloat(f: float; format: FloatFormatMode = ffDefault;
                    precision: range[-1 .. 32] = 16; decimalSep = '.'): string {...}{.noSideEffect,
        gcsafe, extern: "nsu$1", raises: [], tags: [].}

  Converts a floating point value `f` to a string.

  If `format == ffDecimal` then precision is the number of digits to be printed after the decimal point. If `format == ffScientific` then precision is the maximum number of significant digits to be printed. `precision`'s default value is the maximum number of meaningful digits after the decimal point for Nim's `float` type.

  If `precision == -1`, it tries to format it nicely.

  Examples:

      let x = 123.456
      doAssert x.formatFloat() == "123.4560000000000"
      doAssert x.formatFloat(ffDecimal, 4) == "123.4560"
      doAssert x.formatFloat(ffScientific, 2) == "1.23e+02"

  Source Edit

    proc trimZeros(x: var string) {...}{.noSideEffect, raises: [], tags: [].}

  Trim trailing zeros from a formatted floating point value `x` (must be declared as `var`).

  This modifies `x` itself, it does not return a copy.

  Examples:

      var x = "123.456000000"
      x.trimZeros()
      doAssert x == "123.456"

  Source Edit

    proc formatSize(bytes: int64; decimalSep = '.'; prefix = bpIEC; includeSpace = false): string {...}{.
        noSideEffect, raises: [], tags: [].}

  Rounds and formats `bytes`.

  By default, uses the IEC/ISO standard binary prefixes, so 1024 will be formatted as 1KiB. Set prefix to `bpColloquial` to use the colloquial names from the SI standard (e.g. k for 1000 being reused as 1024).

  `includeSpace` can be set to true to include the (SI preferred) space between the number and the unit (e.g. 1 KiB).

  See also:

  - strformat module for string interpolation and formatting

  Examples:

      doAssert formatSize((1'i64 shl 31) + (300'i64 shl 20)) == "2.293GiB"
      doAssert formatSize((2.234 * 1024 * 1024).int) == "2.234MiB"
      doAssert formatSize(4096, includeSpace = true) == "4 KiB"
      doAssert formatSize(4096, prefix = bpColloquial, includeSpace = true) == "4 kB"
      doAssert formatSize(4096) == "4KiB"
      doAssert formatSize(5378934, prefix = bpColloquial, decimalSep = ',') == "5,13MB"

  Source Edit

    proc formatEng(f: BiggestFloat; precision: range[0 .. 32] = 10; trim: bool = true;
                  siPrefix: bool = false; unit: string = ""; decimalSep = '.';
                  useUnitSpace = false): string {...}{.noSideEffect, raises: [], tags: [].}

  Converts a floating point value `f` to a string using engineering notation.

  Numbers in of the range -1000.0<f<1000.0 will be formatted without an exponent. Numbers outside of this range will be formatted as a significand in the range -1000.0<f<1000.0 and an exponent that will always be an integer multiple of 3, corresponding with the SI prefix scale k, M, G, T etc for numbers with an absolute value greater than 1 and m, Î¼, n, p etc for numbers with an absolute value less than 1.

  The default configuration (`trim=true` and `precision=10`) shows the shortest form that precisely (up to a maximum of 10 decimal places) displays the value. For example, 4.100000 will be displayed as 4.1 (which is mathematically identical) whereas 4.1000003 will be displayed as 4.1000003.

  If `trim` is set to true, trailing zeros will be removed; if false, the number of digits specified by `precision` will always be shown.

  `precision` can be used to set the number of digits to be shown after the decimal point or (if `trim` is true) the maximum number of digits to be shown.

      formatEng(0, 2, trim=false) == "0.00"
      formatEng(0, 2) == "0"
      formatEng(0.053, 0) == "53e-3"
      formatEng(52731234, 2) == "52.73e6"
      formatEng(-52731234, 2) == "-52.73e6"

  If `siPrefix` is set to true, the number will be displayed with the SI prefix corresponding to the exponent. For example 4100 will be displayed as "4.1 k" instead of "4.1e3". Note that `u` is used for micro- in place of the greek letter mu (Î¼) as per ISO 2955. Numbers with an absolute value outside of the range 1e-18<f<1000e18 (1a<f<1000E) will be displayed with an exponent rather than an SI prefix, regardless of whether `siPrefix` is true.

  If `useUnitSpace` is true, the provided unit will be appended to the string (with a space as required by the SI standard). This behaviour is slightly different to appending the unit to the result as the location of the space is altered depending on whether there is an exponent.

      formatEng(4100, siPrefix=true, unit="V") == "4.1 kV"
      formatEng(4.1, siPrefix=true, unit="V") == "4.1 V"
      formatEng(4.1, siPrefix=true) == "4.1" # Note lack of space
      formatEng(4100, siPrefix=true) == "4.1 k"
      formatEng(4.1, siPrefix=true, unit="") == "4.1 " # Space with unit=""
      formatEng(4100, siPrefix=true, unit="") == "4.1 k"
      formatEng(4100) == "4.1e3"
      formatEng(4100, unit="V") == "4.1e3 V"
      formatEng(4100, unit="", useUnitSpace=true) == "4.1e3 " # Space with useUnitSpace=true

  `decimalSep` is used as the decimal separator.

  See also:

  - strformat module for string interpolation and formatting
  Source Edit

    proc addf(s: var string; formatstr: string; a: varargs[string, `$`]) {...}{.noSideEffect,
        gcsafe, extern: "nsuAddf", raises: [ValueError], tags: [].}

  The same as `add(s, formatstr % a)`, but more efficient. Source Edit

    proc `%`(formatstr: string; a: openArray[string]): string {...}{.noSideEffect, gcsafe,
        extern: "nsuFormatOpenArray", raises: [ValueError], tags: [].}

  Interpolates a format string with the values from `a`.

  The substitution operator performs string substitutions in `formatstr` and returns a modified `formatstr`. This is often called string interpolation.

  This is best explained by an example:

      "$1 eats $2." % ["The cat", "fish"]

  Results in:

      "The cat eats fish."

  The substitution variables (the thing after the `$`) are enumerated from 1 to `a.len`. To produce a verbatim `$`, use `$$`. The notation `$#` can be used to refer to the next substitution variable:

      "$# eats $#." % ["The cat", "fish"]

  Substitution variables can also be words (that is `[A-Za-z_]+[A-Za-z0-9_]*`) in which case the arguments in `a` with even indices are keys and with odd indices are the corresponding values. An example:

      "$animal eats $food." % ["animal", "The cat", "food", "fish"]

  Results in:

      "The cat eats fish."

  The variables are compared with `cmpIgnoreStyle`. `ValueError` is raised if an ill-formed format string has been passed to the `%` operator.

  See also:

  - strformat module for string interpolation and formatting
  Source Edit

    proc `%`(formatstr, a: string): string {...}{.noSideEffect, gcsafe,
                                        extern: "nsuFormatSingleElem",
                                        raises: [ValueError], tags: [].}

  This is the same as `formatstr % [a]` (see % proc). Source Edit

    proc format(formatstr: string; a: varargs[string, `$`]): string {...}{.noSideEffect, gcsafe,
        extern: "nsuFormatVarargs", raises: [ValueError], tags: [].}

  This is the same as `formatstr % a` (see % proc) except that it supports auto stringification.

  See also:

  - strformat module for string interpolation and formatting
  Source Edit

    proc strip(s: string; leading = true; trailing = true; chars: set[char] = Whitespace): string {...}{.
        noSideEffect, gcsafe, extern: "nsuStrip", raises: [], tags: [].}

  Strips leading or trailing `chars` (default: whitespace characters) from `s` and returns the resulting string.

  If `leading` is true (default), leading `chars` are stripped. If `trailing` is true (default), trailing `chars` are stripped. If both are false, the string is returned unchanged.

  See also:

  - stripLineEnd proc

  Examples:

      let a = "  vhellov   "
      let b = strip(a)
      doAssert b == "vhellov"
      doAssert a.strip(leading = false) == "  vhellov"
      doAssert a.strip(trailing = false) == "vhellov   "
      doAssert b.strip(chars = {'v'}) == "hello"
      doAssert b.strip(leading = false, chars = {'v'}) == "vhello"
      let c = "blaXbla"
      doAssert c.strip(chars = {'b', 'a'}) == "laXbl"
      doAssert c.strip(chars = {'b', 'a', 'l'}) == "X"

  Source Edit

    proc stripLineEnd(s: var string) {...}{.raises: [], tags: [].}

  Returns `s` stripped from one of these suffixes: `\r, \n, \r\n, \f, \v` (at most once instance). For example, can be useful in conjunction with `osproc.execCmdEx`. aka: chomp

  Examples:

      var s = "foo\n\n"
      s.stripLineEnd
      doAssert s == "foo\n"
      s = "foo\c\n"
      s.stripLineEnd
      doAssert s == "foo"

  Source Edit

    proc editDistance(a, b: string): int {...}{.noSideEffect, gcsafe, extern: "nsuEditDistance", deprecated: "use editdistance.editDistanceAscii instead",
                                      raises: [], tags: [].}

  Deprecated: use editdistance.editDistanceAscii instead

  Returns the edit distance between `a` and `b`.

  This uses the Levenshtein distance algorithm with only a linear memory overhead.

  Source Edit

    proc isNilOrEmpty(s: string): bool {...}{.noSideEffect, procvar, gcsafe,
                                     extern: "nsuIsNilOrEmpty",
                                     deprecated: "use \'x.len == 0\' instead",
                                     raises: [], tags: [].}

  Deprecated: use 'x.len == 0' instead
  Checks if `s` is nil or empty. Source Edit

    proc isNilOrWhitespace(s: string): bool {...}{.noSideEffect, procvar, gcsafe,
                                          extern: "nsuIsNilOrWhitespace", raises: [],
                                          tags: [].}

  Checks if `s` is nil or consists entirely of whitespace characters. Source Edit

    proc isAlphaAscii(s: string): bool {...}{.noSideEffect, procvar, gcsafe,
                                     extern: "nsuIsAlphaAsciiStr", deprecated: "Deprecated since version 0.20 since its semantics are unclear",
                                     raises: [], tags: [].}

  Deprecated: Deprecated since version 0.20 since its semantics are unclear

  Checks whether or not `s` is alphabetical.

  This checks a-z, A-Z ASCII characters only. Returns true if all characters in `s` are alphabetic and there is at least one character in `s`. Use Unicode module for UTF-8 support.

  Examples:

      doAssert isAlphaAscii("fooBar") == true
      doAssert isAlphaAscii("fooBar1") == false
      doAssert isAlphaAscii("foo Bar") == false

  Source Edit

    proc isAlphaNumeric(s: string): bool {...}{.noSideEffect, procvar, gcsafe,
                                       extern: "nsuIsAlphaNumericStr", deprecated: "Deprecated since version 0.20 since its semantics are unclear",
                                       raises: [], tags: [].}

  Deprecated: Deprecated since version 0.20 since its semantics are unclear

  Checks whether or not `s` is alphanumeric.

  This checks a-z, A-Z, 0-9 ASCII characters only. Returns true if all characters in `s` are alpanumeric and there is at least one character in `s`. Use Unicode module for UTF-8 support.

  Examples:

      doAssert isAlphaNumeric("fooBar") == true
      doAssert isAlphaNumeric("fooBar1") == true
      doAssert isAlphaNumeric("foo Bar") == false

  Source Edit

    proc isDigit(s: string): bool {...}{.noSideEffect, procvar, gcsafe, extern: "nsuIsDigitStr", deprecated: "Deprecated since version 0.20 since its semantics are unclear",
                                raises: [], tags: [].}

  Deprecated: Deprecated since version 0.20 since its semantics are unclear

  Checks whether or not `s` is a numeric value.

  This checks 0-9 ASCII characters only. Returns true if all characters in `s` are numeric and there is at least one character in `s`.

  Examples:

      doAssert isDigit("1908") == true
      doAssert isDigit("fooBar1") == false

  Source Edit

    proc isSpaceAscii(s: string): bool {...}{.noSideEffect, procvar, gcsafe,
                                     extern: "nsuIsSpaceAsciiStr", deprecated: "Deprecated since version 0.20 since its semantics are unclear",
                                     raises: [], tags: [].}

  Deprecated: Deprecated since version 0.20 since its semantics are unclear

  Checks whether or not `s` is completely whitespace.

  Returns true if all characters in `s` are whitespace characters and there is at least one character in `s`.

  Examples:

      doAssert isSpaceAscii("   ") == true
      doAssert isSpaceAscii("") == false

  Source Edit

    proc isLowerAscii(s: string; skipNonAlpha: bool): bool {...}{.deprecated: "Deprecated since version 0.20 since its semantics are unclear",
        raises: [], tags: [].}

  Deprecated: Deprecated since version 0.20 since its semantics are unclear

  Checks whether `s` is lower case.

  This checks ASCII characters only.

  If `skipNonAlpha` is true, returns true if all alphabetical characters in `s` are lower case. Returns false if none of the characters in `s` are alphabetical.

  If `skipNonAlpha` is false, returns true only if all characters in `s` are alphabetical and lower case.

  For either value of `skipNonAlpha`, returns false if `s` is an empty string. Use Unicode module for UTF-8 support.

  Examples:

      doAssert isLowerAscii("1foobar", false) == false
      doAssert isLowerAscii("1foobar", true) == true
      doAssert isLowerAscii("1fooBar", true) == false

  Source Edit

    proc isUpperAscii(s: string; skipNonAlpha: bool): bool {...}{.deprecated: "Deprecated since version 0.20 since its semantics are unclear",
        raises: [], tags: [].}

  Deprecated: Deprecated since version 0.20 since its semantics are unclear

  Checks whether `s` is upper case.

  This checks ASCII characters only.

  If `skipNonAlpha` is true, returns true if all alphabetical characters in `s` are upper case. Returns false if none of the characters in `s` are alphabetical.

  If `skipNonAlpha` is false, returns true only if all characters in `s` are alphabetical and upper case.

  For either value of `skipNonAlpha`, returns false if `s` is an empty string. Use Unicode module for UTF-8 support.

  Examples:

      doAssert isUpperAscii("1FOO", false) == false
      doAssert isUpperAscii("1FOO", true) == true
      doAssert isUpperAscii("1Foo", true) == false

  Source Edit

    proc wordWrap(s: string; maxLineWidth = 80; splitLongWords = true;
                 seps: set[char] = Whitespace; newLine = "\n"): string {...}{.noSideEffect,
        gcsafe, extern: "nsuWordWrap",
        deprecated: "use wrapWords in std/wordwrap instead", raises: [], tags: [].}

  Deprecated: use wrapWords in std/wordwrap instead
  Word wraps `s`. Source Edit

# Iterators

    iterator split(s: string; sep: char; maxsplit: int = -1): string {...}{.raises: [], tags: [].}

  Splits the string `s` into substrings using a single separator.

  Substrings are separated by the character `sep`. The code:

      for word in split(";;this;is;an;;example;;;", ';'):
        writeLine(stdout, word)

  Results in:

      ""
      ""
      "this"
      "is"
      "an"
      ""
      "example"
      ""
      ""
      ""

  See also:

  - rsplit iterator
  - splitLines iterator
  - splitWhitespace iterator
  - split proc
  Source Edit

    iterator split(s: string; seps: set[char] = Whitespace; maxsplit: int = -1): string {...}{.
        raises: [], tags: [].}

  Splits the string `s` into substrings using a group of separators.

  Substrings are separated by a substring containing only `seps`.

      for word in split("this\lis an\texample"):
        writeLine(stdout, word)

  ...generates this output:

      "this"
      "is"
      "an"
      "example"

  And the following code:

      for word in split("this:is;an$example", {';', ':', '$'}):
        writeLine(stdout, word)

  ...produces the same output as the first example. The code:

      let date = "2012-11-20T22:08:08.398990"
      let separators = {' ', '-', ':', 'T'}
      for number in split(date, separators):
        writeLine(stdout, number)

  ...results in:

      "2012"
      "11"
      "20"
      "22"
      "08"
      "08.398990"

  See also:

  - rsplit iterator
  - splitLines iterator
  - splitWhitespace iterator
  - split proc
  Source Edit

    iterator split(s: string; sep: string; maxsplit: int = -1): string {...}{.raises: [], tags: [].}

  Splits the string `s` into substrings using a string separator.

  Substrings are separated by the string `sep`. The code:

      for word in split("thisDATAisDATAcorrupted", "DATA"):
        writeLine(stdout, word)

  Results in:

      "this"
      "is"
      "corrupted"

  See also:

  - rsplit iterator
  - splitLines iterator
  - splitWhitespace iterator
  - split proc
  Source Edit

    iterator rsplit(s: string; sep: char; maxsplit: int = -1): string {...}{.raises: [], tags: [].}

  Splits the string `s` into substrings from the right using a string separator. Works exactly the same as split iterator except in reverse order.

      for piece in "foo:bar".rsplit(':'):
        echo piece

  Results in:

      "bar"
      "foo"

  Substrings are separated from the right by the char `sep`.

  See also:

  - split iterator
  - splitLines iterator
  - splitWhitespace iterator
  - rsplit proc
  Source Edit

    iterator rsplit(s: string; seps: set[char] = Whitespace; maxsplit: int = -1): string {...}{.
        raises: [], tags: [].}

  Splits the string `s` into substrings from the right using a string separator. Works exactly the same as split iterator except in reverse order.

      for piece in "foo bar".rsplit(WhiteSpace):
        echo piece

  Results in:

      "bar"
      "foo"

  Substrings are separated from the right by the set of chars `seps`

  See also:

  - split iterator
  - splitLines iterator
  - splitWhitespace iterator
  - rsplit proc
  Source Edit

    iterator rsplit(s: string; sep: string; maxsplit: int = -1; keepSeparators: bool = false): string {...}{.
        raises: [], tags: [].}

  Splits the string `s` into substrings from the right using a string separator. Works exactly the same as split iterator except in reverse order.

      for piece in "foothebar".rsplit("the"):
        echo piece

  Results in:

      "bar"
      "foo"

  Substrings are separated from the right by the string `sep`

  See also:

  - split iterator
  - splitLines iterator
  - splitWhitespace iterator
  - rsplit proc
  Source Edit

    iterator splitLines(s: string; keepEol = false): string {...}{.raises: [], tags: [].}

  Splits the string `s` into its containing lines.

  Every character literal newline combination (CR, LF, CR-LF) is supported. The result strings contain no trailing end of line characters unless parameter `keepEol` is set to `true`.

  Example:

      for line in splitLines("\nthis\nis\nan\n\nexample\n"):
        writeLine(stdout, line)

  Results in:

      ""
      "this"
      "is"
      "an"
      ""
      "example"
      ""

  See also:

  - splitWhitespace iterator
  - splitLines proc
  Source Edit

    iterator splitWhitespace(s: string; maxsplit: int = -1): string {...}{.raises: [], tags: [].}

  Splits the string `s` at whitespace stripping leading and trailing whitespace if necessary. If `maxsplit` is specified and is positive, no more than `maxsplit` splits is made.

  The following code:

      let s = "  foo \t bar  baz  "
      for ms in [-1, 1, 2, 3]:
        echo "------ maxsplit = ", ms, ":"
        for item in s.splitWhitespace(maxsplit=ms):
          echo '"', item, '"'

  ...results in:

      ------ maxsplit = -1:
      "foo"
      "bar"
      "baz"
      ------ maxsplit = 1:
      "foo"
      "bar  baz  "
      ------ maxsplit = 2:
      "foo"
      "bar"
      "baz  "
      ------ maxsplit = 3:
      "foo"
      "bar"
      "baz"

  See also:

  - splitLines iterator
  - splitWhitespace proc
  Source Edit

    iterator tokenize(s: string; seps: set[char] = Whitespace): tuple[token: string,
        isSep: bool] {...}{.raises: [], tags: [].}

  Tokenizes the string `s` into substrings.

  Substrings are separated by a substring containing only `seps`. Example:

      for word in tokenize("  this is an  example  "):
        writeLine(stdout, word)

  Results in:

      ("  ", true)
      ("this", false)
      (" ", true)
      ("is", false)
      (" ", true)
      ("an", false)
      ("  ", true)
      ("example", false)
      ("  ", true)

  Source Edit

# Exports

toLower, toLower, toUpper, toUpper