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Creates a temporary file. It is a version of tmpfile with security enhancements as described in Security Features in the CRT.

errno_t tmpfile_s(
   FILE** pFilePtr

[out] pFilePtr

The address of a pointer to store the address of the generated pointer to a stream.

Returns 0 if successful, an error code on failure.

Error Conditions


Return Value

Contents of pFilePtr



not changed

If the above parameter validation error occurs, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, errno is set to EINVAL and the return value is EINVAL.

The tmpfile_s function creates a temporary file and puts a pointer to that stream in the pFilePtr argument. The temporary file is created in the root directory. To create a temporary file in a directory other than the root, use tmpnam_s or tempnam in conjunction with fopen.

If the file cannot be opened, tmpfile_s writes NULL to the pFilePtr parameter. This temporary file is automatically deleted when the file is closed, when the program terminates normally, or when _rmtmp is called, assuming that the current working directory does not change. The temporary file is opened in w+b (binary read/write) mode.

Failure can occur if you attempt more than TMP_MAX_S (see STDIO.H) calls with tmpfile_s.


Required header



For additional compatibility information, see Compatibility in the Introduction.

Note Note

This example requires administrative privileges to run on Windows Vista.

// crt_tmpfile_s.c
// This program uses tmpfile_s to create a
// temporary file, then deletes this file with _rmtmp.

#include <stdio.h>

int main( void )
   FILE *stream;
   char tempstring[] = "String to be written";
   int  i;
   errno_t err;

   // Create temporary files.
   for( i = 1; i <= 3; i++ )
      err = tmpfile_s(&stream);
      if( err )
         perror( "Could not open new temporary file\n" );
         printf( "Temporary file %d was created\n", i );

   // Remove temporary files.
   printf( "%d temporary files deleted\n", _rmtmp() );
Temporary file 1 was created
Temporary file 2 was created
Temporary file 3 was created
3 temporary files deleted

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.