Template:Str index
Usage
edit{{str index|text|number}} = Returns the number-th character of text. Base 1: the first character is numbered 1, and so on.
Only supports a limited character set. Returns an error on unknown characters. Returns   for a blank space.
Template:Str character set/doc
Examples
edit{{str index|0123456789ABCDEF|15}}
→ E{{str index|0123456789ABCDEF|18}}
→ ((str index)): String is not long enough.{{str len|{{str index|a b|2}}}}}}
→ 5 (because the return is 
rather than a space character.)