Writes formatted output to an open file

#include <stdio.h>
int fprintf ( FILE * restrict fp , const char * restrict format , ... );

The fprintf( ) function is similar to printf( ), but writes its output to the stream specified by fp rather than to stdout.

Example

FILE *fp_log;
time_t sec;

fp_log = fopen("example.log", "a");
if ( fp != NULL)
{
  time(&sec);
  fprintf( fp_log, "%.24s Opened log file.\n", ctime( &sec ) );
}

This code appends the following output to the file example.log:

Wed Dec  8 21:10:43 2004 Opened log file.

See Also

printf( ), sprintf( ), snprintf( ), declared in stdio.h; vprintf( ), vfprintf( ), vsprintf( ), vsnprintf( ), declared in stdio.h and stdarg.h; the wide-character functions wprintf( ), fwprintf( ), swprintf( ), declared in stdio.h and wchar.h; vwprintf( ), vfwprintf( ), and vswprintf( ), declared in stdio.h, wchar.h, and stdarg.h; the scanf( ) input functions. Argument conversion in the printf( ) family of functions is described under printf( ) in this chapter.