Lord knows why the NSIS folks didn’t add a CharAt function to their API.
In case you need it to parse a string, here’s a Macro that makes StrCpy work like a CharAt function
[bash]
;Get a character inside a string given an index.
;Usage: CharAt String Index Output
!macro CharAt InputString Index Output
StrCpy ${Output} ${InputString} 1 ${Index}
!macroend
[/bash]
To use the CharAt “function” (macro in this case), do as follows:
[bash]
!insertmacro CharAt "Hello World!" 1 $0
;$0 will have the letter ‘e’ inside.
[/bash]