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Passing String Parameters to WinAPI Functions (Views: 100)


Problem/Question/Abstract:

I'm using the Winexec command and trying to use a string as the argument, but Winexec takes only a Pchar as its argument. I can't figure out how to put a regular string into a Pchar, or how to make a Pchar 'point' to a character string.

Answer:

WinAPI calls can be pretty confusing, huh? Let's say you have a function called WinAPICall that takes a PChar as an argument. Here are a couple of ways to make the call:

First Method (This will only work for Delphi 2.0 and above, which supports casting):

WinAPICall(PChar(MyStringVal));

Second Method:

procedure CallWinApiCall(S: string);
var
  Val: string;
  pVal: PChar;
begin
  Val := S;
  {Initialize memory for the PChar}
  GetMem(pVal, Length(Val));

  {Copy the contents of Val to PChar}
  pVal := StrPCopy(pVal, Val);
  WinAPICall(pVal);

  {This next step is ABSOLUTELY necessary}
  FreeMem(pVal, Length(Val));
end;

In any case, that should do it for you pretty nicely.

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