_fprintf_p, _fprintf_p_l, _fwprintf_p, _fwprintf_p_l

Article
06/05/2017

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The latest version of this topic can be found at _fprintf_p, _fprintf_p_l, _fwprintf_p, _fwprintf_p_l.

Prints formatted data to a stream.

Syntax

int _fprintf_p(   
   FILE *stream,  
   const char *format [,  
   argument ]...  
);  
int _fprintf_p_l(   
   FILE *stream,  
   const char *format,  
   locale_t locale [,  
   argument ]...  
);  
int _fwprintf_p(   
   FILE *stream,  
   const wchar_t *format [,  
   argument ]...  
);  
int _fwprintf_p_l(   
   FILE *stream,  
   const wchar_t *format,  
   locale_t locale [,  
   argument ]...  
);

Parameters

stream
Pointer to the FILE structure.

format
Format-control string.

argument
Optional arguments.

locale
The locale to use.

Return Value

_fprintf_p and _fwprintf_p return the number of characters written or return a negative value when an output error occurs.

Remarks

_fprintf_p formats and prints a series of characters and values to the output stream. Each function argument (if any) is converted and output according to the corresponding format specification in format. For _fprintf_p, the format argument has the same syntax and use that it has in _printf_p. These functions support positional parameters, meaning that the order of the parameters used by the format string can be changed. For more information about positional parameters, see printf_p Positional Parameters.

_fwprintf_p is a wide-character version of _fprintf_p; in _fwprintf_p, format is a wide-character string. These functions behave identically if the stream is opened in ANSI mode. _fprintf_p doesn't currently support output into a UNICODE stream.

The versions of these functions with the _l suffix are identical except that they use the locale parameter passed in instead of the current locale.

Important

Ensure that format is not a user-defined string.

Like the non-secure versions (see fprintf, _fprintf_l, fwprintf, _fwprintf_l), these functions validate their parameters and invoke the invalid parameter handler, as described in Parameter Validation, if either stream or format is a null pointer or if there are any unknown or badly formed formatting specifiers. If execution is allowed to continue, the functions return -1 and set errno to EINVAL.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
`_ftprintf_p`	`_fprintf_p`	`_fprintf_p`	`_fwprintf_p`
`_ftprintf_p_l`	`_fprintf_p_l`	`_fprintf_p_l`	`_fwprintf_p_l`

For more information, see Format Specifications.

Requirements

Function	Required header
`_fprintf_p`, `_fprintf_p_l`	<stdio.h>
`_fwprintf_p`, `_fwprintf_p_l`	<stdio.h> or <wchar.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_fprintf_p.c  
// This program uses _fprintf_p to format various  
// data and print it to the file named FPRINTF_P.OUT. It  
// then displays FPRINTF_P.OUT on the screen using the system  
// function to invoke the operating-system TYPE command.  
//   
  
#include <stdio.h>  
#include <process.h>  
  
int main( void )  
{  
    FILE    *stream = NULL;  
    int     i = 10;  
    double  fp = 1.5;  
    char    s[] = "this is a string";  
    char    c = '\n';  
  
    // Open the file  
    if ( fopen_s( &stream, "fprintf_p.out", "w" ) == 0)  
    {  
        // Format and print data  
        _fprintf_p( stream, "%2$s%1$c", c, s );  
        _fprintf_p( stream, "%d\n", i );  
        _fprintf_p( stream, "%f\n", fp );  
  
        // Close the file  
        fclose( stream );  
    }  
  
    // Verify our data  
    system( "type fprintf_p.out" );  
}

this is a string  
10  
1.500000

.NET Framework Equivalent

System::IO::StreamWriter::Write

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