const與重載

class SignatureDemo {


public:


    SignatureDemo(int val) : m_Val(val) {}


    void demo(int n)


        {cout << ++m_Val << "/tdemo(int)" << endl;}


    void demo(int n) const 




        {cout << m_Val << "/tdemo(int) const" << endl;}


/*  void demo(const int& n)   


      {cout << ++m_Val << "/tdemo(int&)" << endl;}  */ 


//必然衝突


    void demo(short s)  


        {cout << ++m_Val << "/tdemo(short)" << endl;}


    void demo(float f)  


        {cout << ++m_Val << "/tdemo(float)" << endl;}


    void demo(float f) const 


        {cout << m_Val << "/tdemo(float) const" << endl;}


    void demo(double d)


        {cout << ++m_Val << "/tdemo(double)" << endl;}


private:


    int m_Val;


};




int main() {


    SignatureDemo sd(5);


    const SignatureDemo csd(17);


    sd.demo(2);    


    csd.demo(2);   


    int i = 3;


    sd.demo(i);


    short s = 5;


    sd.demo(s);


    csd.demo(s); 




    sd.demo(2.3);   




    float f(4.5);   


    sd.demo(f);


    csd.demo(f);    


    csd.demo(4.5);  


    return 0;


}



result:




   6       demo(int)


   17      demo(int) const


   7       demo(int)


   8       demo(short)


   17      demo(int) const


   9       demo(double)


   10      demo(float)


   17      demo(float) const




評註：const 在方法上，可以重載；const在參數上，不能重載；double型常量在必要時自動轉型，以對應函數參數