为啥我不能在 C++ 中更新我的类属性？

Posted 2023-02-22

【中文标题】为啥我不能在 C++ 中更新我的类属性？

【英文标题】：Why can't I update my class properties in C++?为什么我不能在 C++ 中更新我的类属性？

【发布时间】：2021-09-05 09:44:06

【问题描述】：

我正在制作一个向导游戏原型，但遇到了一个问题：

我创建了一个名为 Wizard 的类和一个名为 Goblin 的类：

class Wizard

    public:
        int damage;
        int health;
        int stamina;

        Wizard(int d, int h, int s)
        
            d = damage;
            h = health;
            s = stamina;
        

        float getDamage()  return damage; 
        void setDamage(int v)  v = damage; 

        float getHealth()  return health; 
        void setHealth(int v)  v = health; 

        float getStamina()  return stamina; 
        void setStamina(float v)  v = stamina; 

;

class Goblin

    public:
        int health;
        int damage;

        Goblin(int h, int d)
        
            h = health;
            d = damage;
        

        float getHealth()  return health; 
        void setHealth(int v)  v = health; 

        float getDamage()  return damage; 
        void setDamage(int v)  v = damage; 
;

然后，我为它们声明并初始化变量：

Wizard wizard(50, 150, 10);
Goblin goblin(150, 25);

然后，我创建了一个attack() 函数：

void attack(Wizard attacker, Goblin target)

    if(target.getDamage() > 0.0)
    
        attacker.setStamina(attacker.getStamina() - 1);
    

所以，在主函数中，我调用了attack并打印出结果：

int main()

    attack(wizard, goblin);
    printInfo();

    return 0;

但结果是这样的：

> clang++-7 -pthread -std=c++17 -o main main.cpp
> ./main
Wizard Health: 0
Wizard Damage: 0
Wizard Stamina: 0

Goblin Damage: 0
Goblin Health: 0

我还创建了一个printInfo() 函数：

void printInfo()

    std::cout << "Wizard Health: " << wizard.getHealth() << std::endl;
    std::cout << "Wizard Damage: " << wizard.getDamage() << std::endl;
    std::cout << "Wizard Stamina: " << wizard.getStamina() << std::endl;
    
    std::cout << std::endl;

    std::cout << "Goblin Damage: " << goblin.getHealth() << std::endl;
    std::cout << "Goblin Health: " << goblin.getDamage() << std::endl;

如果你需要，这里是完整的文件：

#include <iostream>

class Wizard

    public:
        int damage;
        int health;
        int stamina;

        Wizard(int d, int h, int s)
        
            d = damage;
            h = health;
            s = stamina;
        

        float getDamage()  return damage; 
        void setDamage(int v)  v = damage; 

        float getHealth()  return health; 
        void setHealth(int v)  v = health; 

        float getStamina()  return stamina; 
        void setStamina(float v)  v = stamina; 

;

class Goblin

    public:
        int health;
        int damage;

        Goblin(int h, int d)
        
            h = health;
            d = damage;
        

        float getHealth()  return health; 
        void setHealth(int v)  v = health; 

        float getDamage()  return damage; 
        void setDamage(int v)  v = damage; 
;

Wizard wizard(50, 150, 10);
Goblin goblin(150, 25);

void attack(Wizard attacker, Goblin target);
void printInfo();

int main()

    attack(wizard, goblin);
    printInfo();

    return 0;


void attack(Wizard attacker, Goblin target)

    if(target.getDamage() > 0.0)
    
        attacker.setStamina(attacker.getStamina() - 1);
    


void printInfo()

    std::cout << "Wizard Health: " << wizard.getHealth() << std::endl;
    std::cout << "Wizard Damage: " << wizard.getDamage() << std::endl;
    std::cout << "Wizard Stamina: " << wizard.getStamina() << std::endl;
    
    std::cout << std::endl;

    std::cout << "Goblin Damage: " << goblin.getHealth() << std::endl;
    std::cout << "Goblin Health: " << goblin.getDamage() << std::endl;

很抱歉，如果这很长，但我们将不胜感激。

【问题讨论】：

在您将h 分配给health 的构造函数中，它应该是相反的。其他领域也是如此。

在设置器中存在与 Raildex 提到的问题相同的问题。我习惯在成员变量前加上m_，这可能有助于避免混淆。顺便说一句：为什么你的吸气剂返回float？成员变量具有 int 类型，setter 也采用 int...

【参考方案1】：

您的attack() 函数按值接受参数。因此，它会修改您的全局变量的副本。

使用参考：

void attack(Wizard& attacker, Goblin& target)

    ...

PS：另见 https://en.cppreference.com/w/cpp/language/constructor 了解成员初始化列表

【讨论】：

您可能想提及在设置器/构造器中以“反向”完成分配的问题...

一次一节课?

【参考方案2】：

在您的构造函数和 set* 方法中，您需要将输入参数值分配给类的成员变量。反之亦然。

#include <iostream>

class Wizard

    public:
        int damage;
        int health;
        int stamina;

        Wizard(int d, int h, int s)
        
            damage = d;
            health = h;
            stamina = s;
        

        float getDamage()  return damage; 
        void setDamage(int v)  damage = v; 

        float getHealth()  return health; 
        void setHealth(int v)  health = v; 

        float getStamina()  return stamina; 
        void setStamina(float v)  stamina = v; 

;

class Goblin

    public:
        int health;
        int damage;

        Goblin(int h, int d)
        
            health = h;
            damage = d;
        

        float getHealth()  return health; 
        void setHealth(int v)  health = v; 

        float getDamage()  return damage; 
        void setDamage(int v)  damage = v; 
;

Wizard wizard(50, 150, 10);
Goblin goblin(150, 25);

void attack(Wizard attacker, Goblin target);
void printInfo();

int main()

    attack(wizard, goblin);
    printInfo();

    return 0;


void attack(Wizard attacker, Goblin target)

    if(target.getDamage() > 0.0)
    
        attacker.setStamina(attacker.getStamina() - 1);
    


void printInfo()

    std::cout << "Wizard Health: " << wizard.getHealth() << std::endl;
    std::cout << "Wizard Damage: " << wizard.getDamage() << std::endl;
    std::cout << "Wizard Stamina: " << wizard.getStamina() << std::endl;
    
    std::cout << std::endl;

    std::cout << "Goblin Damage: " << goblin.getHealth() << std::endl;
    std::cout << "Goblin Health: " << goblin.getDamage() << std::endl;

【讨论】：

谢谢，但 Ralidex 已经回答了。这些值正在打印，但未更新。