C语言用指针拷贝数组的调用函数的顺序问题

Question

这是一个用三个函数分别把source数组拷贝给三个target数组的代码，为什么现在这样运行target2打印出来是一堆随机的奇怪数字，但是把函数2和函数3的调用换一下位置，又运行正常了呢？

#include<stdio.h>
void copy_arr(double* t, double* s, int n);
void copy_ptr(double* t, double* s, int n);
void copy_ptrs(double* t, double* s, float* n);
int main(void)
{
    const double source[5] = { 1.1,2.2,3.3,4.4,5.5 };
    double target1[5];
    double target2[5];
    double target3[5];
    int index;
    copy_arr(target1, source, 5);     //函数1
    copy_ptr(target2, source, 5);     //函数2
    copy_ptrs(target3, source, source + 5);     //函数3

    printf("target1: ");
    for (index = 0; index < 5; index++)
        printf("%5g", target1[index]);
    printf("\n\n");

    printf("target2: ");
    for (index = 0; index < 5; index++)
        printf("%5g", target2[index]);
    printf("\n\n");

    printf("target3: ");
    for (index = 0; index < 5; index++)
        printf("%5g", target3[index]);
    printf("\n\n");

    return 0;
}

void copy_arr(double* t, double* s, int n)
{
    int i;
    for (i = 0; i < n; i++)
        t[i] = s[i];
}

void copy_ptr(double* t, double* s, int n)
{
    for (int i = 0; i < n; i++)
        *(t + i) = *(s + i);
}

void copy_ptrs(double* t, double* s, float* n)
{
    int x, i;
    x = n - s;
    for (i = 0; i < x; i++)
        *(t + i) = *(s + i);
}

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Answer 1

修改如下，改动处见注释，供参考：

#include<stdio.h>
void copy_arr(double* t, double* s, int n);
void copy_ptr(double* t, double* s, int n);
void copy_ptrs(double* t,double* s, double* n); //float* n 修改
int main(void)
{
    const double source[5] = { 1.1,2.2,3.3,4.4,5.5 };
    double target1[5];
    double target2[5];
    double target3[5];
    int index;
    copy_arr(target1, source, 5);     //函数1
    copy_ptr(target2, source, 5);     //函数2
    copy_ptrs(target3, source, source + 5);//函数3

    printf("target1: ");
    for (index = 0; index < 5; index++)
        printf("%5g", target1[index]);
    printf("\n\n");

    printf("target2: ");
    for (index = 0; index < 5; index++)
        printf("%5g", target2[index]);
    printf("\n\n");

    printf("target3: ");
    for (index = 0; index < 5; index++)
        printf("%5g", target3[index]);
    printf("\n\n");
    return 0;
}

void copy_arr(double* t,double* s, int n)
{
    int i;
    for (i = 0; i < n; i++)
        t[i] = s[i];
}

void copy_ptr(double* t,double* s, int n)
{
    int i; // 修改
    for (i = 0; i < n; i++) // 修改
        *(t + i) = *(s + i);
}

void copy_ptrs(double* t,double* s, double* n) //float* n 修改
{
    int x, i;
    x = n - s;
    for (i = 0; i < x; i++)
        *(t + i) = *(s + i);
}