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Get the Length of a String (number of Characters) in Python

Modified: | Tags: Python, String

In Python, you can get the length of a string (str), which is the number of characters, using the built-in len() function.

Contents

To learn how to count specific characters or substrings, see the following article.

For more on using len() with other types like list, see the following article.

Get the length of a string (number of characters) using len()

By passing a string to the built-in len() function, its length (the number of characters) is returned as an integer value.

s = 'abcde'

print(len(s))
# 5
source: str_len.py

Full-width and half-width characters

Both full-width and half-width characters are each counted as a single character.

s = 'あいうえお'

print(len(s))
# 5

s = 'abcdeあいうえお'

print(len(s))
# 10
source: str_len.py

Escape sequences and special characters

In Python, special characters like TAB are represented with a backslash, as in \t. The backslash itself is represented by \\. These special characters are considered single characters.

s = 'a\tb\\c'
print(s)
# a b\c

print(len(s))
# 5
source: str_len.py

In raw strings, escape sequences are not interpreted and the string is treated as-is. The number of characters is also counted as-is.

s = r'a\tb\\c'
print(s)
# a\tb\\c

print(len(s))
# 7
source: str_len.py

A Unicode escape sequence, such as \uXXXX, is also treated as a single character.

s = '\u3042\u3044\u3046'
print(s)
# あいう

print(len(s))
# 3
source: str_len.py

In raw strings, even Unicode escape sequences are not interpreted and are treated as literal text.

s = r'\u3042\u3044\u3046'
print(s)
# \u3042\u3044\u3046

print(len(s))
# 18
source: str_len.py

Line breaks

\n (LF: Line Feed) is also considered a single character.

s = 'a\nb'
print(s)
# a
# b

print(len(s))
# 3
source: str_len.py

If \r\n (CR: Carriage Return + LF: Line Feed) is used, it is counted as two characters, \r and \n.

s = 'a\r\nb'
print(s)
# a
# b

print(len(s))
# 4
source: str_len.py

If \n and \r\n are mixed in the same text, the number of characters used to represent line breaks will differ.

s = 'abc\nabcd\r\nab'
print(s)
# abc
# abcd
# ab

print(len(s))
# 12
source: str_len.py

To handle mixed \n and \r\n, you can use the splitlines() method, which splits the string into lines and returns them as a list.

print(s.splitlines())
# ['abc', 'abcd', 'ab']
source: str_len.py

The number of elements in the list returned by splitlines() corresponds to the number of lines.

print(len(s.splitlines()))
# 3
source: str_len.py

You can get the number of characters in each line using a list comprehension.

print([len(line) for line in s.splitlines()])
# [3, 4, 2]
source: str_len.py

To calculate the total number of characters, use sum() with a generator expression. Generator expressions are enclosed in () instead of []. When used within another (), as in this example, the enclosing parentheses can be omitted.

print(sum(len(line) for line in s.splitlines()))
# 9
source: str_len.py

For more information about handling line breaks, see the following article.

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