C程序——指针数组乘法

Question

程序应该取两个数组，并对数组中的每个元素进行点积。

如果n的索引小于5，我的程序没问题;然而，一旦数组的索引大于5，只有第一个数组中的第一个元素是错误的(我通过在函数中添加printf语句来检查)。我不知道如何修复这个错误。

#include <stdio.h>
void multi_vec(int *v1, int *v2, int *v3, int n);
int main(void)
{
    int n, i;
    int v1[n];
    int v2[n];
    int v3[n];
    printf("Enter the length of the two vectorsn");
    scanf("%d", &n);
    printf("Enter numbers for the first arrayn", n);
    for (i = 0; i < n; i++) {
        scanf("%d", &v1[i]);
    }
    printf("Enter numbers for the second arrayn", n);
    for (i = 0; i < n; i++) {
         scanf("%d", &v2[i]);
    }
    multi_vec(v1, v2, v3, n);
    for (i = 0; i < n; i++) {
        printf("%d", v3[i]);
    }
    printf("n");
    return 0;
}
void multi_vec(int *v1, int *v2, int *v3, int n)
{
    int i;
    for (i = 0; i < n; i++) {
        *(v3+i) = *(v1+i) * *(v2+i);
    }
}

Answer 1

正确代码

#include <stdio.h>
void multi_vec(int *v1, int *v2, int *v3, int n);
int main(void)
{
    int n, i;
    printf("Enter the length of the two vectorsn");
    scanf("%d", &n);
    int v1[n],v2[n],v3[n];     //you didn't initialize n
    printf("Enter numbers for the first arrayn");    //printf statements had extra ',n'
    for (i = 0; i < n; i++) {
        scanf("%d", &v1[i]);
    }
    printf("Enter numbers for the second arrayn");    //printf statements had extra ',n'
    for (i = 0; i < n; i++) {
         scanf("%d", &v2[i]);
    }
    multi_vec(v1, v2, v3, n);
    for (i = 0; i < n; i++) {
        printf("%d ", v3[i]);
    }
    printf("n");
    return 0;
}
void multi_vec(int *v1, int *v2, int *v3, int n)
{
    int i;
    for (i = 0; i < n; i++) {
        *(v3+i) = *(v1+i) * *(v2+i);
    }
}