数组与指针(数组中所有元素的和)

//1.下面这个例子是计算数组中所有元素的和
//数组与指针的关系,整型是4个字节,a[] == *a, a[i] = *(a+i)
#include <stdio.h>
#define SIZE 10
int sum (int a[],int n);
int main(){

    int ar [SIZE] = {10,20,30,40,50,60,70,80,90};
    long answer;
    answer = sum(ar, SIZE);   //重点是这一句,ar为int [10]类型
    printf("%lu\n",sizeof(answer)); //answer是long 型 8个字节
    printf("answer=%lu\n",answer); //结果是450;
    return 0;
}
int sum (int a[]/***a*/, int n){//两种等价

    int total = 0,i = 0;
    for (i = 0; i < n; i++) {
//        total += a[i];  //上面和下面的两种公式是等价,
        total += *(a+i);
    }
    return total;
}

数组中所有元素的和.