变长参数表

 #include <stdarg.h> /* minprintf: minimal printf with variable argument list */ void minprintf(char *fmt, ...) { va_list ap; /* points to each unnamed arg in turn */ char *p, *sval; int ival; double dval; va_start(ap, fmt); /* make ap point to 1st unnamed arg */ for (p = fmt; *p; p++) { if (*p != '%') { putchar(*p); continue; } switch (*++p) { case 'd': ival = va_arg(ap, int); printf("%d", ival); break; case 'f': dval = va_arg(ap, double); printf("%f", dval); break; case 's': for (sval = va_arg(ap, char *); *sval; sval++) putchar(*sval); break; default: putchar(*p); break; } } va_end(ap); /* clean up when done */ }