Need to replace characters in string InnoSetup

Question

Our company just switched to InnoSetup and i don't know how to pass data to/from variables in InnoSetup Pascal Script.

I read the manual and wrote a function that turns versions like '0.5.0.2' to '0.5.2'.

I get a weird error (that i'm missing a semicolon at line 5) - could anyone help me?

#define ApplicationVersion GetVersionNumbersString(ApplicationEXE)

function InitializeSetup(): Boolean;  
var
S: String;
begin
  // not working, but also tried S := ApplicationVersion;
  S := ExpandConstant({#ApplicationVersion});

  StringChangeEx(S, '.0.', '.', True);
  ApplicationVersion := S;
end;