C++实现一个最基本的类

女爷i 2022-02-25 03:22 103阅读 0赞

1.将类的成员函数的声明与实现分开来写；这种写法会使得代码更加清晰，但此时对成员函数的调用要经过函数压栈操作，对于简单代码段来说，执行效率会比较低。

/*---------------------------------------
    功能：定义一个CPU类，并实现其相关功能
    运行结果：
    Calling argument constructor of CPU...
    The CPU is running...
    The CPU is stopped...
    Calling destruct of CPU...
    -----------------------------------------
    Author: Zhang Kaizhou
    Date: 2019-3-31 16:53:22
    ----------------------------------------*/
    #include <iostream>
    
    using namespace std;
    
    enum CPU_Rank{P1 = 1, P2, P3, P4, P5, P6, P7}; // 声明一个枚举数据类型，名字为CPU_Rank
    class CPU{
    public:
        CPU(CPU_Rank r, int f, float v); // 含参构造函数
        CPU(); // 默认构造函数
        ~CPU(); // 析构函数
        void setRank(CPU_Rank r);
        void setFrequency(int frequency);
        void setvoltage(float v);
        CPU_Rank getRank();
        int getFrequency();
        float getVoltage();
        void run();
        void stop();
    private:
        CPU_Rank rank;
        int frequency;
        float voltage;
    };
    
    CPU::CPU(CPU_Rank r, int f, float v):rank(r), frequency(f), voltage(v){ // 含参构造函数的实现
        cout << "Calling argument constructor of CPU..." << endl;
    }
    CPU::CPU(){ // 默认构造函数的实现
        cout << "Calling default constructor of CPU..." << endl;
    }
    
    CPU::~CPU(){ // 析构函数的实现
        cout << "Calling destruct of CPU..." << endl;
    }
    
    void CPU::setRank(CPU_Rank r){
        rank = r;
    }
    
    void CPU::setFrequency(int f){
        frequency = f;
    }
    
    void CPU::setvoltage(float v){
        voltage = v;
    }
    
    CPU_Rank CPU::getRank(){
        return rank;
    }
    
    int CPU::getFrequency(){
        return frequency;
    }
    
    float CPU::getVoltage(){
        return voltage;
    }
    
    void CPU::run(){
        cout << "The CPU is running..." << endl;
    }
    
    void CPU::stop(){
        cout << "The CPU is stopped..." << endl;
    }
    
    int main(){
        CPU a(P6, 300, 2.8);
        a.run();
        a.stop();
    
        return 0;
    }

2.将类的成员函数的声明和实现都在类的内部实现；此时的成员函数为内联成员函数，调用是采用的是代码段覆盖的方式，不需要函数压栈，对于简单代码段来说，效率更高些。

/*---------------------------------------
    功能：定义一个CPU类，并实现其相关功能
    运行结果：
    Calling argument constructor of CPU...
    The CPU is running...
    The CPU is stopped...
    Calling destruct of CPU...
    -----------------------------------------
    Author: Zhang Kaizhou
    Date: 2019-3-31 17:01:20
    ----------------------------------------*/
    #include <iostream>
    
    using namespace std;
    
    enum CPU_Rank{P1 = 1, P2, P3, P4, P5, P6, P7}; // 声明一个枚举数据类型，名字为CPU_Rank
    class CPU{
    public:
        CPU(CPU_Rank r, int f, float v):rank(r), frequency(f), voltage(v){ // 含参构造函数的实现
            cout << "Calling argument constructor of CPU..." << endl;
        }
        CPU(){ // 默认构造函数的实现
            cout << "Calling default constructor of CPU..." << endl;
        }
    
        ~CPU(){ // 析构函数的实现
            cout << "Calling destruct of CPU..." << endl;
        }
    
        void setRank(CPU_Rank r){
            rank = r;
        }
    
        void setFrequency(int f){
            frequency = f;
        }
    
        void setvoltage(float v){
            voltage = v;
        }
    
        CPU_Rank getRank(){
            return rank;
        }
    
        int getFrequency(){
            return frequency;
        }
    
        float getVoltage(){
            return voltage;
        }
    
        void run(){
            cout << "The CPU is running..." << endl;
        }
    
        void stop(){
            cout << "The CPU is stopped..." << endl;
        }
    private:
        CPU_Rank rank;
        int frequency;
        float voltage;
    };
    
    int main(){
        CPU a(P6, 300, 2.8);
        a.run();
        a.stop();
    
        return 0;
    }

3.将类的成员函数的声明与实现分开来写，但是对于那些较短的，结构相对简单的（内部不含有循环结构）成员函数可使用"inline"关键字将其定义为内联函数，从而提高代码的执行效率；

/*---------------------------------------
    功能：定义一个CPU类，并实现其相关功能
    运行结果：
    Calling argument constructor of CPU...
    The CPU is running...
    The CPU is stopped...
    Calling destruct of CPU...
    -----------------------------------------
    Author: Zhang Kaizhou
    Date: 2019-3-31 17:07:48
    ----------------------------------------*/
    #include <iostream>
    
    using namespace std;
    
    enum CPU_Rank{P1 = 1, P2, P3, P4, P5, P6, P7}; // 声明一个枚举数据类型，名字为CPU_Rank
    class CPU{
    public:
        CPU(CPU_Rank r, int f, float v); // 含参构造函数
        CPU(); // 默认构造函数
        ~CPU(); // 析构函数
        void setRank(CPU_Rank r);
        void setFrequency(int frequency);
        void setvoltage(float v);
        CPU_Rank getRank();
        int getFrequency();
        float getVoltage();
        void run();
        void stop();
    private:
        CPU_Rank rank;
        int frequency;
        float voltage;
    };
    
    inline CPU::CPU(CPU_Rank r, int f, float v):rank(r), frequency(f), voltage(v){ // 含参构造函数的实现
        cout << "Calling argument constructor of CPU..." << endl;
    }
    inline CPU::CPU(){ // 默认构造函数的实现
        cout << "Calling default constructor of CPU..." << endl;
    }
    
    inline CPU::~CPU(){ // 析构函数的实现
        cout << "Calling destruct of CPU..." << endl;
    }
    
    inline void CPU::setRank(CPU_Rank r){
        rank = r;
    }
    
    inline void CPU::setFrequency(int f){
        frequency = f;
    }
    
    inline void CPU::setvoltage(float v){
        voltage = v;
    }
    
    inline CPU_Rank CPU::getRank(){
        return rank;
    }
    
    inline int CPU::getFrequency(){
        return frequency;
    }
    
    inline float CPU::getVoltage(){
        return voltage;
    }
    
    inline void CPU::run(){
        cout << "The CPU is running..." << endl;
    }
    
    inline void CPU::stop(){
        cout << "The CPU is stopped..." << endl;
    }
    
    int main(){
        CPU a(P6, 300, 2.8);
        a.run();
        a.stop();
    
        return 0;
    }

**总结：**  
个人比较推荐第三种代码风格，既可以保证代码清晰，有能有效地提高代码的执行效率。