Cpp小作业-帮助理解Cpp的类，参数，函数

题目要求：

You are asked to create a C++ program that simulates the movements of two mobile robots. Call it main.cpp or similar.

1. Define a class that represents the robot. The robot should have the following attributes: (i) a name, for example, a C-style string, (ii) a position on a two-dimensional grid (use integers), and (iii) an orientation on this grid (4 possibilities). Define two reasonable constructors and a destructor. Define a method (that is, a function of the class) that prints the robot's status (that is, its name, position and orientation) using cout. Define a method that moves the robot forward by k steps, where k is the function argument. Define two further operations that rotate the robot clockwise and anti-clockwise, respectively (by 90 degree). Describe your source code through concise comments (// ...).
2. Test your class implementation as follows (and include this in your main.cpp as well). Create two robots called Alice and Bob, and initialise them at positions (2, 4) and (4, 1), respectively. Alice should initially be oriented along the positive y axis direction, whereas Bob should initially be oriented along the positive x axis direction [where the axes are such that the general position is (x,y)]. Perform the following sequence of operations:

• Alice and Bob print their status.
• Alice moves forward by 2 steps. Bob moves forward by 1 steps.
• Alice and Bob print their status.
• Alice rotates counter-clockwise and then moves forward by 3 steps. Bob rotates counter-clockwise and then moves forward by 4 steps.
• Alice and Bob print their status.

简单来说，创建一个Robot的Class，为其添加命名，坐标，转向三项功能并打印这些参数。

作为一个只有JAVA基础从来没学过Cpp的彩笔，刚上手还确实有些难度，想框架3分钟，改bug3小时。

几个难住我的点

1.没有与这些操作匹配的 << 运算符

 

这个困扰了我很久，最后发现错的非常离谱。

忘记了加

#include<string>

......

2. 非标准语法；请使用"&"来创建指向成员的指针

Bob.printStatus;

在这里，使用的应是成员函数，而非类的成员变量。

当使用class的成员函数时，VS并不会帮我们加上圆括号, 所以很多新人（比如我）就会忘记加上 ( ) 来表示函数调用。

不加括号的时候，也就是函数不传入参数的话(包括void)，编译器会理解成函数指针，但是函数指针正确写法是

    &Bob.printStatus;

 因此便有了上面的错误提示。

来自: 错误 "xxxx":C++提示非标准语法；请使用 "&" 来创建指向成员的指针_勇搏风浪的博客-CSDN博客

 

 

解决了报错以后就很简单了，权当复习了一下JAVA，项目代码如下：

/*
    ID: 210110131
    Name: Fangyuan Wei
    Date: 04/11/2021
*/
#include <iostream>
#include<string>
using namespace std;

class Robot {
public:
    string robotname;        //Robot name
    int xPosition;            //Robot x-axis position
    int yPosition;            //Robot y-axis position
    int directions = 0; //1 = right→+x, 2 = up→+y , 3 = left→-x, 4 = down→-y. Refer to Cartesian coordinate system

    Robot(string name, int xPos, int yPos, int direction) {
        robotname = name;
        xPosition = xPos;
        yPosition = yPos;
        directions = direction;
    }

    void moveForward(int step) {        //Robot move forward
        switch (directions) {            //different situation for steps
        case 1:
            xPosition = xPosition + step;
            break;
        case 2:
            yPosition = yPosition + step;
            break;
        case 3:
            xPosition = xPosition - step;
            break;
        case 4:
            yPosition = yPosition - step;
            break;
        }
    }
    void rotateClock() {            //rotate clockwise
        if (directions != 1){
            directions--;
        }
        else {
            directions = 4;
        }
    }
    void rotateCounterClock() {        //rotate counterclockwise
        if (directions != 4){
            directions++;
        }
        else {
            directions = 1;
        }
    }
    void printStatus() {            //print status of robot
        string dirEN;
        switch (directions)            //change the format of direction from numbers to words
        {
        case 1:
            dirEN = "Positive X direction";
            break;
        case 2:
            dirEN = "Positive Y direction";
            break;
        case 3:
            dirEN = "Negative X direction";
            break;
        case 4:
            dirEN = "Negative Y direction";
            break;
        default:
            break;
        }
        cout << "The robotname is " << robotname << "," << endl;
        cout << "the X Position is " << xPosition << "," << endl;
        cout << "the Y Position is " << yPosition << "," << endl;
        cout << "Direction is " << dirEN << "," << endl;
        cout << "-----Brilliant-----Cutting-----Lineeeeeeee-----" << endl;
    }
};
int main() {
    //cout << "hello world" << endl;
    Robot Alice("Alice",2,4,2);
    Robot Bob("Bob",4,1,1);
    Alice.printStatus();
    Bob.printStatus();

    Alice.moveForward(2);
    Bob.moveForward(1);
    Alice.printStatus();
    Bob.printStatus();

    Alice.rotateCounterClock();
    Alice.moveForward(3);
    Bob.rotateCounterClock();
    Bob.moveForward(4);
    Alice.printStatus();
    Bob.printStatus();
    return 0;
}

输出：