Variable-length Argument Lists

最新推荐文章于 2019-05-04 22:12:37 发布

wegatron

最新推荐文章于 2019-05-04 22:12:37 发布

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分类专栏： c 文章标签： function each list 语言 up c

本文链接：https://blog.csdn.net/wegatron/article/details/7968595

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C 语言的可变参数函数样例，摘自《The c programming language》

#include <stdarg.h>

void minprintf(char *fmt, ...)
{
	va_list ap;	/*points to each unnamed arg in turn */
	char *p, *sval;
	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);	/* va_arg returns one argument and strps ap to the next. */
				printf("%f", dval);
				break;
			case 's':
				for (sval = va_varg(ap, char *); *sval; sval++)
					putchar(*sval);
				break;
			default:
				putchar(*p);
				break;
		}
	}
	va_end(ap);	/* clean up when done, it is necessary, must be called before the function returns. */
}