C++编写一个程序，初始化一个 double 类型的数组，然后把该数组的内容拷贝至3个其他数组中（在 main()中声明这 4 个数组）。使用带数组表示法的函数进行第1份拷贝。使用带指针表示法和指针递增的函数进行第2份拷贝。 把目标数组名、源数组名和待拷贝的元素个数作为前两个函数的参数。第 3 个函数以目标数组名、源数组名和指向源数组最后一个元素后面的元素的指针。

也就是说，给定以下声明，则函数调用如下所示：

double source[5] = {1.1, 2.2, 3.3, 4.4, 5.5};

double target1[5];

double target2[5];

double target3[5];

copy_arr(target1, source, 5);

copy_ptr(target2, source, 5);

copy_ptrs(target3, source, source + 5);

#include <iostream>
#include <string>
#include <windows.h>
using namespace std;
void copy_arr(double target1[], double source[], int len) {
    for (int i = 0; i < len; i++) {
        target1[i] = source[i];
    }
}
void copy_ptr(double* target2, double* source, int len) {
    for (int i = 0; i < len; i++) {
        *target2++ = *(source +i);
    }
}
void copy_ptrs(double* target3, double* source_start, double* source_end) {
    for (; source_start < source_end; source_start++) {
        *target3 = *source_start;
        target3++;
    }
}
int main() {
    double source[5] = {1.1,2.2,3.3,4.4,5.5};
    double target1[5];
    double target2[5];
    double target3[5];

    copy_arr(target1, source, 5);
    cout << "target1:";
    for (int i = 0; i < sizeof(source) / sizeof(source[0]); i++){
        cout << target1[i] << " ";
    }
    cout << endl;

    copy_ptr(target2, source, 5);
    cout << "target2:";
    for (int i = 0; i < sizeof(source) / sizeof(source[0]); i++) {
        cout << target2[i] << " ";
    }
    cout << endl;

    copy_ptrs(target3, source, source+5);
    cout << "target3:";
    for (int i = 0; i < sizeof(source) / sizeof(source[0]); i++) {
        cout << target3[i] << " ";
    }
    cout << endl;

    system("pause");
    return 0;
}