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_sprintf_p, _sprintf_p_l, _swprintf_p, _swprintf_p_l

Write formatted data to a string with the ability to specify the order that the parameters are used in the format string.

int _sprintf_p(
   char *buffer,
   size_t sizeOfBuffer,
   const char *format [,
   argument] ... 
int _sprintf_p_l(
   char *buffer,
   size_t sizeOfBuffer,
   const char *format,
   locale_t locale [,
   argument] ... 
int _swprintf_p(
   wchar_t *buffer,
   size_t sizeOfBuffer,
   const wchar_t *format [,
int _swprintf_p_l(
   wchar_t *buffer,
   size_t sizeOfBuffer,
   const wchar_t *format,
   locale_t locale [,
   argument] … 

Storage location for output


Maximum number of characters to store.


Format-control string


Optional arguments


The locale to use.

For more information, see Format Specifications.

The number of characters written, or –1 if an error occurred.

The _sprintf_p function formats and stores a series of characters and values in buffer. Each argument (if any) is converted and output according to the corresponding format specification in format. The format consists of ordinary characters and has the same form and function as the format argument for printf_p. A NULL character is appended after the last character written. If copying occurs between strings that overlap, the behavior is undefined. The difference between _sprintf_p and sprintf_s is that _sprintf_p supports positional parameters, which allows specifying the order in which the arguments are used in the format string. For more information, see printf_p Positional Parameters.

_swprintf_p is a wide-character version of _sprintf_p; the pointer arguments to _swprintf_p are wide-character strings. Detection of encoding errors in _swprintf_p may differ from that in _sprintf_p. _swprintf_p and fwprintf_p behave identically except that _swprintf_p writes output to a string rather than to a destination of type FILE, and _swprintf_p requires the countparameter to specify the maximum number of characters to be written. The versions of these functions with the _l suffix are identical except that they use the locale parameter passed in instead of the current thread locale.

_sprintf_p returns the number of bytes stored in buffer, not counting the terminating NULL character. _swprintf_preturns the number of wide characters stored in buffer, not counting the terminating NULL wide character. If buffer or format is a null pointer, or if the format string contains invalid formatting characters, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, these functions return -1 and set errno to EINVAL.

Generic-Text Routine Mappings

TCHAR.H routine

_UNICODE & _MBCS not defined

_MBCS defined

_UNICODE defined










Required header

_sprintf_p , _sprintf_p_l


_swprintf_p , _swprintf_p_l

<stdio.h> or <wchar.h>

For additional compatibility information, see Compatibility in the Introduction.

// crt_sprintf_p.c
// This program uses _sprintf_p to format various
// data and place them in the string named buffer.

#include <stdio.h>

int main( void )
    char     buffer[200],
            s[] = "computer", c = 'l';
    int      i = 35,
    float    fp = 1.7320534f;

    // Format and print various data: 
    j  = _sprintf_p( buffer, 200,
                     "   String:    %s\n", s );
    j += _sprintf_p( buffer + j, 200 - j, 
                     "   Character: %c\n", c );
    j += _sprintf_p( buffer + j, 200 - j, 
                     "   Integer:   %d\n", i );
    j += _sprintf_p( buffer + j, 200 - j, 
                     "   Real:      %f\n", fp );

    printf( "Output:\n%s\ncharacter count = %d\n", 
            buffer, j );
   String:    computer
   Character: l
   Integer:   35
   Real:      1.732053

character count = 79
// crt_swprintf_p.c
// This is the wide character example which
// also demonstrates _swprintf_p returning
// error code.
#include <stdio.h>

#define BUFFER_SIZE 100

int main( void )
    wchar_t buffer[BUFFER_SIZE];
    int     len;

    len = _swprintf_p(buffer, BUFFER_SIZE, L"%2$s %1$d",
                      0, L" marbles in your head.");
    _printf_p( "Wrote %d characters\n", len );
    // _swprintf_p fails because string contains WEOF (\xffff)
    len = _swprintf_p(buffer, BUFFER_SIZE, L"%s", 
                      L"Hello\xffff world" );
    _printf_p( "Wrote %d characters\n", len );
Wrote 24 characters
Wrote -1 characters
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