关于数组元素初始化有一些小问题

Question

RT
最近写的几个小程序中几乎所有的数组元素初始化都有问题，求大神看看是哪里有问题

 //求一个4*4二维数组的对角线上的值的和
#include<stdio.h>
int main (void)
{
    int array[3][3],sum = 0;
    int i = 0,j = 0;
    printf("Please enter the numbers(16 numbers inside):\n");
    for (i = 0;i <=3 ;i++){
        for(j = 0;j <= 3;j++)
            scanf("%d",&array[i][j]);
    }
    printf("\n");
    for (i = 0;i <=3 ;i++){
        for(j = 0;j <= 3;j++)
            printf("%d ",array[i][j]);
        printf("\n");
    }
    for (i = 0, j = 0;i <= 3;i++,j++)
        sum += array[i][j];
    printf("sum = %d",sum);
    return 0;
}

这是第一个程序及运行结果

 //做一个20元素数组，将偶数位下标相加，奇数位下标相乘
#include<stdio.h>
int main (void)
{
    double array[19],son = 1,sen = 0;
    int i = 0;
    printf("Please enter the numbers(20 numbers inside):\n");
    for (i = 0;i <= 19;i++)
        scanf("%lf",&array[i]);
    for (i = 0;i <= 19;i++)
        printf("%.0lf ",array[i]);
    printf("\n");
    for (i = 0;i <= 19;i += 2)
        sen += array[i];
    for (i = 1;i <= 19;i += 2)
        son *= array[i];
    printf("The sum of even numbers is %.2lf.\n",sen);
    printf("The product of odd numbers is %.2lf.\n",son);
    return 0;
}

这是第二个程序及运行结果
不知道为什么每个数组最后一个元素都有问题
求解

Answer 1

int array[3][3]，数组下标从0开始，到2；

 for (i = 0;i <=3 ;i++)改为：
 for (i = 0;i <3 ;i++)