Lua - Split String

Splitting a string is the process in which we pass a regular expression or pattern with which one can split a given string into different parts.

In Lua, there is no split function that is present inside the standard library but we can make use of other functions to do the work that normally a split function would do.

A very simple example of a split function in Lua is to make use of the gmatch() function and then pass a pattern which we want to separate the string upon.

Example - Spliting Strings

Consider the example shown below −

main.lua

-- define a local variable
local example = "lua is great"
-- split string based on space
for i in string.gmatch(example, "%S+") do
   -- print the substring
   print(i)
end

Output

When we run the above code, we will get the following output−

lua
is
great

The above example works fine for simple patterns but when we want to make use of a regular expression and the case that we can have a default pattern with which to split, we can consider a more elegant example.

Example - Using regular expression

Consider the example shown below −

main.lua

-- define a function to spring a string with give separator
function mysplit (inputstr, sep)
   -- if sep is null, set it as space
   if sep == nil then
      sep = '%s'
   end
   -- define an array
   local t={}
   -- split string based on sep   
   for str in string.gmatch(inputstr, '([^'..sep..']+)') 
   do
      -- insert the substring in table
      table.insert(t, str)
   end
   -- return the array
   return t
end
-- split the string based on space
ans = mysplit('hey bro whats up?')
-- iterate through array of substrings
for _, v in ipairs(ans) 
do 
   print(v) 
end
-- split the string based on comma
-- iterate through array of substrings
ans = mysplit('x,y,z,m,n',',')
for _, v in ipairs(ans) 
do 
   print(v) 
end

Output

When we run the above code, we will get the following output−

hey
bro
whats
up?
x
y
z
m
n