Delegating Constructors - C++ Class

C++ examples for Class:Constructor

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Introduction

A class can have several constructors.

The code for one constructor can call another of the same class in the initialization list.

The implementation of the first constructor can be: 

                                                                                                                                  
Pool::Pool(double lv, double wv, double hv) : length {lv}, width {wv}, height {hv}
{
  std::cout << "Pool constructor 1 called." << std::endl;
}

The second constructor creates a Pool object with all sides equal and we can implement it like this: 

                                                                                                                                  
Pool::Pool(double side) : Pool {side, side, side}
{
  std::cout << "Pool constructor 2 called." << std::endl;
}

Here's a simple illustration of this using the Pool class:

Demo Code

                                                                                                                                  
#include <iostream>
class Pool//from   w  w w.j  a v a 2s.  co  m
{
private:
  double length {1.0};
  double width {1.0};
  double height {1.0};
                                                                                                                                  
public:
  // Constructors
  Pool(double lv, double wv, double hv);
  Pool(double side);                         // Constructor for a cube
  Pool() {}                                  // No-arg constructor
                                                                                                                                  
  double volume();                          // Function to calculate the volume of a pool
};
                                                                                                                                  
Pool::Pool(double lv, double wv, double hv) : length {lv}, width {wv}, height {hv} {
  std::cout << "Pool constructor 1 called." << std::endl;
}
                                                                                                                                  
Pool::Pool(double side) : Pool {side, side, side} {
  std::cout << "Pool constructor 2 called." << std::endl;
}
                                                                                                                                 
                                                                                                                                  
int main()
{
  Pool pool1 {2.0, 3.0, 4.0};           // An arbitrary pool
  Pool pool2 {5.0};                     // A pool that is a cube
                                                                                                                                  
}

Result


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