CString?

Prof. A Olowofoyeku (The African Chief) chiefsoft at bigfoot.com
Tue Apr 29 15:35:14 CEST 2003


 Peter N Lewis wrote:
 
>Could someone explain o me what CString is in the RTS?
 
It is the same thing as BP and Delphi's "pChar" (aka a null-
terminated string). It is used mainly to interface to C library (and, 
for example, Windows and OS/2 API) routines, and can often be used 
where the C library expects a "char *" or anything of the kind, or 
where the WinAPI expects "LPCSTR" or any other variation of that. The 
"strings" and Sysutils units contain a number of routines for dealing 
with such null-terminated strings.

 >It seems it is a pointer, and the docs somewhere describe it as
 >^Char, and it is generally used as a pointer, but some places it is
 >used as an array, as in   Dest[Size] := #0;

Yes. You can do this in BP/Delphi - but I am not sure whether it is 
inherent in the type or whether GPC just allows this to be compatible 
with BP.

BTW: a CString/pChar is type-compatible with zero-based arrays of 
char (e.g., var foo : array [0..1023] of char). I think you might 
have to use {$X+} in your code for this - but I don't remember (I 
always use it anyway).

 >Since there seems good support for CString in string.pas, I'm trying
 >to figure out if I can use it in the Mac Interfaces, if it is binary
 >compatible with the Mac's definition of CStringPtr = ^Char;
 
I don't know about "binary" but I would have thought it would be 
compatible.

 >BTW, I noticed in string.pas
 >
 >     if (s2 = nil) or (s2^ = #0)
 >
 >I know GPC defaults to always doing short circuit, but would that be
 >better written or_else?

Dunno. I think that expression is one of the safest ways of dealing 
with pChar variables. I don't know what "or_else" means or how it 
differs from "or".

Best regards, 
   The Chief
---------
Prof. Abimbola Olowofoyeku (The African Chief)
Web: http://www.bigfoot.com/~african_chief/




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