在C中指针有问题

Question

所以我有这个代码:

#include <stdio.h>
int arraySum (int *a, int n);
int main(void){
    int values[3] = {1, 2, 3};
    printf("The sum is %i\n", arraySum(values, 3));
    return 0;
}
int arraySum(int *a, int n){
    int sum = 0;
    int arrayEnd = *a + n;
    for ( ; *a < arrayEnd; *a++)
        sum += *a;
    return sum;
}

出于某种原因,它输出:

roman@lmde64 ~/Dropbox/Practice $ gcc practice.c 
roman@lmde64 ~/Dropbox/Practice $ ./a.out
The sum is -421028781
roman@lmde64 ~/Dropbox/Practice $ ./a.out
The sum is -362865581
roman@lmde64 ~/Dropbox/Practice $ ./a.out
The sum is -1046881197
roman@lmde64 ~/Dropbox/Practice $ ./a.out
The sum is 6
roman@lmde64 ~/Dropbox/Practice $ ./a.out
The sum is 6

为什么输出奇怪的数字有时候和正确的答案其他时间？我究竟做错了什么？谢谢你的帮助.

Answer 1

在arraySum(),您将混淆何时a用作指针,何时取消引用它以获取它指向的内容.在计算循环限制等时,您希望使用指针本身:

int arraySum(int *a, int n){
    int sum = 0;
    int *arrayEnd = a + n;
    for ( ; a < arrayEnd; a++)
        sum += *a;
    return sum;
}