定义三维向量类array，利用运算符重载实现array对象的加法（+）、减法（-）与内积（*）。 主函数中程序创建两个array类型的对象A1与A2，并输入六个数字，分别为A1、A2赋值，打印输出A1+A2，A1-A2，A1*A2的结果。

下面是对应的代码实现：

#include <iostream>

using namespace std;

class array {
public:
    double x, y, z;

    array() {}

    array(double x, double y, double z) : x(x), y(y), z(z) {}

    array operator+(const array &v) const {
        return array(x + v.x, y + v.y, z + v.z);
    }

    array operator-(const array &v) const {
        return array(x - v.x, y - v.y, z - v.z);
    }

    double operator*(const array &v) const {
        return x * v.x + y * v.y + z * v.z;
    }
};

int main() {
    double x1, y1, z1, x2, y2, z2;

    cout << "Please input six numbers:" << endl;
    cin >> x1 >> y1 >> z1 >> x2 >> y2 >> z2;

    array A1(x1, y1, z1), A2(x2, y2, z2);

    cout << "A1 + A2 = (" << A1.x + A2.x << ", " << A1.y + A2.y << ", " << A1.z + A2.z << ")" << endl;

    cout << "A1 - A2 = (" << A1.x - A2.x << ", " << A1.y - A2.y << ", " << A1.z - A2.z << ")" << endl;

    cout << "A1 * A2 = " << A1 * A2 << endl;

    return 0;
}

运行结果示例：

Please input six numbers:
1 2 3 4 5 6
A1 + A2 = (5, 7, 9)
A1 - A2 = (-3, -3, -3)
A1 * A2 = 32