可变参数列表

//可变参数列表
#include<stdio.h>
#include<stdarg.h>
double Ave(int num,...){
	int i = 0;
	double sum = 0.0;
	va_list arg;
	va_start(arg, num);
	for (i = 0; i < num; i++){
		sum += va_arg(arg, double);
	}
	va_end(arg);
	return sum / num;
}

int main(){
	double ret = Ave(3, 4.5, 4.4, 4.3);
	printf("ret = %lf\n",ret);
	system("pause");
	return 0;
}

//模拟printf
//print("val:ccc s\n",'b','i','t',"hello");
#include<stdio.h>
#include<stdarg.h>
void Print(const char* str, ...){
	char *p = NULL;
	va_list arg;
	va_start(arg,str);
	while (*str){
		switch (*str){
		case 'c': putchar(va_arg(arg, char)); break;
		case 's': p=va_arg(arg, char *);
			while (*p){
				putchar(*p);
				p++;
			}
			break;
		default: putchar(*str); break;
		}
		str++;
	}
	va_end(arg); 
}
int main(){
	Print("val:ccc s\n",'b','i','t',"hello");
	system("pause");
	return 0;
}