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Vprintf, vfprintf, vsprintf, and vsnprintf

Item Value Header filestdarg.h stdio.h Declarationint vprintf(char *format, va_list arg_ptr); int vfprintf(FILE *stream, const char *format, va_list arg_ptr); int vsprintf(char *buf, const char *format, va_list arg_ptr); int vsnprintf(char * restrict buf, size_t num, const char * restrict format, va_list arg_ptr); The functions vprintf(), vfprintf(), vsprintf(), and vsnprintf() are functionally equivalent to printf(), fprintf(), sprintf(), and snprintf(), respectively , except that the argument list has been replaced by a pointer to a list of arguments. This pointer must be of type va_list, which is defined in the header . #include <stdio.h>   #include <stdarg.h>   void print_message(char *format, ...)   {     va_list ptr;     va_start(ptr, format);     vprintf(format, ptr);     va_end(ptr);   }   int main(void)   {     print_message("Cannot open file %s.", "test");     return 0;   }