C++抽象类练习题——games

Description:

In this problem, you should complete some classes.

You can see more details in sample input / output and main.cpp

Each gameobject will have position,speed, and 10HP.

When you select a gameobject, we will hear it’s voice.You should print this voice.

When you select a worker, you will hear “Scv good to go, sir!”
When you select a zealot, you will hear “My life for Aiur!”
When you select a tower, you will hear nothing, and you can replace it by a “~”

We describe the speed as a vector (dx, dy)
For the three gameobjects, they are (1, 1) (2, 2) and (0, 0). (Tower cannot move.)
When a object moves, you should print where he moves to.

Zealot and tower can attack other objects and their damages are 1.

Worker can repair an object.

When worker build a building, you should print a triangle by ‘*’ with different height.

For example, if the worker build a building with 3 you should print
+
+++
+++++

sample input

1 1
2 2
3 3
4

sample output

test for select:
Scv good to go, sir!
My life for Aiur
~

test for move:
Worker moves to (2, 2)
Zealot moves to (4, 4)
Tower cannot move

test for attack:
Zealot’s hp is 9
Tower’s hp is 9

test for repair:
Zealot’s hp is 10

test for build:
+
+++
+++++
+++++++

题目说明：
题目描述中三角形可能看上去可能会有些问题。高度为3的三角形，第一层为2个空格和一个+，第二层为1个空格和三个+，第三层为5个+

关于move函数，对于原本在(x,y)的对象，移动到(x+dx, y+dy)

为避免奇怪错误，repair 和 attack传参数请传gameobject*

解答：

#ifndef HEADER_H#define HEADER_H#include<iostream>using namespace std;class gameobject {    protected:        double x, y;        double dx, dy;        int hp;    public:        gameobject(double x = 0, double y = 0, double dx = 0, double dy = 0)        : x(x), y(y), dx(dx), dy(dy), hp(10) {}        virtual void select() = 0;        virtual void move() = 0;        void under_attack(int x) {            hp -= x;        }        void get_repaired() {            hp = 10;        }        int get_hp() {            return hp;        }};class worker : public gameobject {    public:        worker(double x = 0, double y = 0) : gameobject(x, y, 1, 1) {}        virtual void select() {            cout << "Scv good to go, sir!\n";        }        virtual void move() {            x += dx;            y += dy;            cout << "Worker moves to (" << x << ", "<< y << ")\n";        }        void repair(gameobject* g) {            g->get_repaired();        }        void build(int x) {            for (int i = 1; i <= x; i++) {                for (int j = 1; j <= x-i; j++) cout << " ";                for (int j = 1; j <= 2*i-1; j++) cout << "*";                cout << endl;            }        }};class zealot : public gameobject {    private:        int _attack;    public:        zealot(double x = 0, double y = 0)        : gameobject(x, y, 2, 2), _attack(1) {}        virtual void select() {            cout << "My life for Aiur!\n";        }        virtual void move() {            x += dx;            y += dy;            cout << "Zealot moves to (" << x << ", "<< y << ")\n";        }        void attack(gameobject* g) {            g->under_attack(_attack);        }};class tower : public gameobject {    private:        int _attack;    public:        tower(double x = 0, double y = 0)        : gameobject(x, y, 0, 0), _attack(1) {}        virtual void select() {            cout << "~\n";        }        virtual void move() {            cout << "Tower cannot move.\n";        }        void attack(gameobject* g) {            g->under_attack(_attack);        }};#endif

测试函数：

#include"header.h"int main() {    gameobject* g;  // gameobject是一个抽象类    worker* w;  // worker zealot tower是派生类    zealot* z;    tower* t;    double x, y;  // (x, y)表示坐标    cin >> x >> y;    w = new worker(x, y);    cin >> x >> y;    z = new zealot(x, y);    cin >> x >> y;    t = new tower(x, y);    // test for select    cout << "test for select:\n";    // 当一个对象被选中时，输出他们的语音。    g = w;    g->select();    g = z;    g->select();    g = t;    g->select();    // test for move    cout << "\ntest for move:\n";    // 当一个对象移动时，输出他们移动到的位置。    g = w;    g->move();    g = z;    g->move();    g = t;    g->move();    // test for others    cout << "\ntest for attack:\n";    z->attack(t);    t->attack(z);    cout << "Zealot's hp is " << z->get_hp() << endl;    cout << "Tower's hp is " << t->get_hp() << endl;    cout << "\ntest for repair:\n";    w->repair(z);  // worker将zealot的HP修复至10    cout << "Zealot's hp is " << z->get_hp() << endl;    int h;    cin >> h;    cout << "\ntest for build:\n";    w->build(h);    delete w;    delete z;    delete t;    return 0;}

心得体会：
games是一道抽象类的基础题
我自己写的父类定义如下：

class gameobject { public:    virtual void select() = 0;    virtual void move() = 0;    virtual void attack(gameobject* t) = 0;    virtual int get_hp() = 0;    int hp;    gameobject() {hp = 10;}};

要注意的一个基本的知识点是，抽象类跟继承是紧密联系在一起的父类是抽象类，其中定义一些virtual的函数，在父类本身不能实例化需要在继承父类的子类中实例化，而且，父类中的virtul函数，在子类中，【都要实例化】，不管你需不需要。
父类中也可以定义一些非virtual的函数，这些函数可以在父类中实例化。

BTW，这是TA定义的抽象父类：

class gameobject {    protected:        double x, y;        double dx, dy;        int hp;    public:        gameobject(double x = 0, double y = 0,double dx = 0, double dy = 0)        : x(x), y(y), dx(dx), dy(dy), hp(10) {}        virtual void select() = 0;        virtual void move() = 0;        void under_attack(int x) {            hp -= x;        }        void get_repaired() {            hp = 10;        }        int get_hp() {            return hp;        }};

把hp等定义为protected，这样对子类来说是public的，对main来说是private的，保护了成员变量。