cppreference.com > Standard C I/O > vprintf, vfprintf, and vsprintf vprintf, vfprintf, and vsprintf Syntax:
      #include <stdarg.h>
      #include <stdio.h>
      int vprintf( char *format, va_list arg_ptr );
      int vfprintf( FILE *stream, const char *format, va_list arg_ptr );
      int vsprintf( char *buffer, char *format, va_list arg_ptr );
These functions are very much like printf(), fprintf(), and sprintf(). The difference is that the argument list is a pointer to a list of arguments. va_list is defined in stdarg.h, and is also used by (Other Standard C Functions) va_arg(). For example:
       void error( char *fmt, ... ) {
         va_list args;
         va_start( args, fmt );
         fprintf( stderr, "Error: " );
         vfprintf( stderr, fmt, args );
         fprintf( stderr, "\n" );
         va_end( args );
         exit( 1 );
       }