vprintf(3S)                                           vprintf(3S)



NAME
     vprintf, vfprintf, vsprintf - format and output data from  a
     variable-length argument list

SYNOPSIS
     #include <stdio.h>
     #include <varargs.h>

     int vprintf(format, ap)
     char *format;
     va_list ap;

     int vfprintf(stream, format, ap)
     FILE *stream;
     char *format;
     va_list ap;

     int vsprintf(s, format, ap)
     char *s, *format;
     va_list ap;

DESCRIPTION
     vprintf, vfprintf, and vsprintf are the same as printf,
     fprintf, and sprintf respectively, except that instead of
     being called with a variable number of arguments, they are
     called with an argument list as defined by varargs(5).

EXAMPLES
     The following demonstrates how vfprintf could be used to
     write an error routine.

     #include <stdio.h>
     #include <varargs.h>
          .
          .
          .
     /*
      *   error should be called like
      *      error(function_name, format, arg1, arg2...);
      */
     /*VARARGS0*/
     void
     error(va_alist)
     /* Note that the function_name and format arguments
      * cannot be separately declared because of the
      */definition of varargs.
     va_dcl
     {
        va_list args;
        char *fmt;

        va_start(args);



January 1992                                                    1

vprintf(3S)                                           vprintf(3S)



        /* print out name of function causing error */
        (void)fprintf(stderr, "ERROR in %s: ",
                           va_arg(args, char *));
        fmt = va_arg(args, char *);
        /* print out remainder of message */
        (void)vfprintf(fmt, args);
        va_end(args);
        (void)abort( );
     }


SEE ALSO
     varargs(5)










































2                                                    January 1992