Const Pointers and const Member Functions - C++ Class

C++ examples for Class:Member Function

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Introduction

If you declare a pointer to a const object, the only functions that you can call with that pointer are const functions.

Demo Code

                                            
#include <iostream> 
                                            
class Rectangle //from  w w w  .ja va  2s . co m
{ 
public: 
    Rectangle(); 
    ~Rectangle(); 
    void SetLength(int length) { itsLength = length; } 
    int GetLength() const { return itsLength; } 
                                            
    void SetWidth(int width) { itsWidth = width; } 
    int GetWidth() const { return itsWidth; } 
                                            
private: 
    int itsLength; 
    int itsWidth; 
}; 
                                            
Rectangle::Rectangle(): 
itsWidth(5), 
itsLength(10) 
{} 
                                            
Rectangle::~Rectangle() 
{} 
                                            
int main() 
{ 
    Rectangle* pRect =  new Rectangle; 
    const Rectangle *pConstRect = new Rectangle; 
    Rectangle * const pConstPtr = new Rectangle; 
                                            
    std::cout << "pRect width: " << pRect->GetWidth() << " feet\n"; 
    std::cout << "pConstRect width: " << pConstRect->GetWidth() << " feet\n"; 
    std::cout << "pConstPtr width: " << pConstPtr->GetWidth() << " feet\n"; 
                                              
    pRect->SetWidth(10); 
    // pConstRect->SetWidth(10); 
    pConstPtr->SetWidth(10); 
                                              
    std::cout << "pRect width: " << pRect->GetWidth() << " feet\n"; 
    std::cout << "pConstRect width: " << pConstRect->GetWidth() << " feet\n"; 
    std::cout << "pConstPtr width: " << pConstPtr->GetWidth() << " feet\n"; 
    return 0; 
}

Result


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