SAS/C Library Reference, Vol. 1

vfprintf -- Write Formatted Output to a File

SYNOPSIS

 #include <stdarg.h>
 #include <stdio.h>

 int vfprintf(FILE *f, const char *format, va_list arg);

DESCRIPTION

vfprintf is equivalent to fprintf with arg replacing the variable-argument list. arg has been initialized by the va_start macro and possibly va_arg calls. vfprintf does not invoke the va_end macro. See va_arg, va_end, and va_start for details on varying-length argument-list functions.

RETURN VALUE

vfprintf returns the number of characters transmitted to the output stream or a negative value if an output error occurs.

EXAMPLE

This example sends an error message prefix with fprintf and sends the remaining text with vfprintf:

  #include <stdarg.h>
  #include <stdio.h>

  void error(char *fname, char *format, ...)
  {
     va_list args;
     va_start(args, format);
     fprintf(stderr, "ERROR in %s: ", fname);
     vfprintf(stderr, format, args);
     va_end(args);
  }

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