String Indexing

BlackBulletIV edited this page May 9, 2011 · 4 revisions
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Strong allows for two types of indexing. These are documented here.

Brackets

Indexing with brackets ([]) allows you to get a single character of a string by provided its index. It's nearly the same as using s:sub(i, i) but it returns nil if the index is out of range.

Example

s = "Hello"
print(s[1]) -- "H"
print(s[3]) -- "l"
print(s[-1]) -- "o"
print(s[20]) -- nil

Calling

For more powerful indexing, you can actually call the strings, as in s(i, j). There are three things you can do with it:

  • If you provide only i, and i is a number, it will be the same as s[i].
  • If you provide i and j, and i is a number, then it will be the same s:sub(i, j), with the exception that it will return nil if i is out of range.
  • Finally, if i is a string it will be the same as s:match(i, j).

Example

s = "Hello"
print(s(2)) -- "e"
print(s(2, 4)) -- "ell"
print(s("ell")) -- "ell"
print(s("nothere")) -- nil
print(s("l", 4)) -- "l"
print(s("l", 5)) -- nil