Winapi: formatting output functions of wvsprintf and wsprintf-Windows

Wvsprintf function declaration:

 
Wvsprintf (output: pchar; {used to return the buffer} format: pchar; {format; similar to the format, it should be the same as the C-language printf format} Arglist: va_list {array pointer}): integer; {length of the actual string returned to the buffer}

  
 

Example of the wvsprintf function:

 
// Example 1: var Buf: pchar; arr: array [0 .. 1] of pointer; begin Buf: = pchar (stringofchar (#0,255); {prepare a buffer like this} arr [0]: = pchar ('in case '); arr [1]: = pointer (123); wvsprintf (BUF, '% s, % d', @ ARR); showmessage (BUF); {display result: In case, 123} end; // Example 2: var Buf: pchar; arr: array of pointer; {the difference with the previous example is that dynamic array is used here} begin Buf: = pchar (stringofchar (#0,255); setlength (ARR, length (ARR) + 1); arr [high (ARR)]: = pchar ('case '); setlength (ARR, length (ARR) + 1); arr [high (ARR)]: = pointer (123); wvsprintf (BUF, '% s, % d ', pchar (ARR); // wvsprintf (BUF, '% s, % d', @ arr [0]); {or so} showmessage (BUF); {display result: in case, 123} end;

  
 

The difference between the wsprintf function and wvsprintf function is that wvsprintf is a set of data, and wsprintf is a set of data. The declaration is as follows:

 
Wsprintf (output: pchar; {buffer returned} format: pchar; {format} data: pointer {Data Pointer}): integer; {length of the actual string returned to the buffer}

  
 

In particular, the wsprintf function declaration in Delphi 2007 is incorrect and a parameter is missing. You need to declare it again:

If it is used only in this unit, you can declare it as follows:

 
... Implementation {$ R *. DFM} function wsprintf (output: pchar; format: pchar; Data: pointer): integer; stdcall; External USER32 name 'wsprintfa ';...
 

If global use requires such declaration:

 
... Function wsprintf (output: pchar; format: pchar; Data: pointer): integer; stdcall; var form1: tform1; implementation {$ R *. DFM} function wsprintf; External USER32 name 'wsprintfa ';...

  
 

Example of the wsprintf function:

Function wsprintf (output: pchar; format: pchar; Data: pointer): integer; stdcall; External USER32 name 'wsprintfa '; Procedure tform1.formcreate (Sender: tobject); var Buf: pchar; begin Buf: = pchar (stringofchar (#0,255); wsprintf (BUF, 'I am % s', pchar (' In case '); showmessage (BUF ); {I am in case} wsprintf (BUF, 'current is % d year', pointer (2008); showmessage (BUF); {now is July 22, 2008} end;

  
 

Finally, use the hexadecimal notation to test their differences with the format function (the format function of Delphi is rewritten by Assembly rather than calling the API ):

 
VaR Buf: pchar; arr: array [0 .. 0] of pointer; I: integer; begin Buf: = pchar (stringofchar (#0,255); I: = maxint; arr [0]: = pointer (I ); showmessage (format ('% x', [I]); {7 fffffff} showmessagefmt (' % x', [I]); {7 fffffffff} wvsprintf (BUF, '% x', @ ARR); showmessage (BUF); {7 fffffff} end;