How to get the first character of a string in Lua?

Question

Given a string s in Lua:

s = "abc123"

If the string is non-empty, I want to store the first character of this string in a variable s1, else store nothing.

I've tried the following, but both return nil:

s1 = s[1]
s1 = s[0]

How can I get the first character without using external Lua libraries?

Answer 1

You can use string.sub() to get a substring of length 1:

> s = "abc123"
> string.sub(s, 1, 1)
a

This also works for empty strings:

> string.sub("", 1, 1) -- => ""