使用可变数目的参数列表

#include <stdio.h>
#include <stdarg.h>
float average(int num, ...);

int main(void){
float x;
x = average(10,1,2,3,4,5,6,7,8,9,10);
printf("\nThe first average is %.2f.", x);
x = average(5,121,206,76,31,5);
printf("\nThe second average is %.2f.\n", x);
return (0);
}

float average(int num, ...){
//声明一个va_list类型的变量
va_list arg_ptr;
int count, total = 0;

//初始化参数指针
va_start(arg_ptr, num);

//从可变参数列表中取回每一个参数
for(count = 0; count < num; count++){
total += va_arg(arg_ptr, int);
}

//执行清理
va_end(arg_ptr);
return((float)total / num);
}