Conversion Constructor in C++
Conversion Constructor
On this page we will discuss about conversion constructor in C++. Constructors are special functions in C++, these are used widely to initialize the objects with values for a class. Conversion constructor is a single parameter constructor.It is declared without the function specifier explicit.
Conversion Constructor in C++ Language
The compiler uses conversion constructor to convert objects from the type of the single parameter to the type of the conversion constructor’s class.
Usage of conversion constructor
- In return value of a function
- As a parameter to a function
New way of calling Constructor
Usual way of calling a constructor is ClassName(variables).
For example: PrepInsta(int x) or PrepInsta(int x, int y)
Using conversion constructor we can call constructor by using assignment operator (=).
For Example –
1. ClassName obj = val (PrepInsta obj = 10)
2. ClassName obj = {val1, val2 ..} (PrepInsta obj = {10, 20})
Single Value Conversion Constructor
Let us look at the code below –
#include <iostream>
using namespace std;
// base class
class Animal {
public:
void jump() {
cout << "I can jump!" << endl;
}
void sit() {
cout << "I can sit!" << endl;
}
};
// derived class
class Dog : public Animal {
public:
void bark() {
cout << "I can bark! Woof woof!!" << endl;
}
};
int main() {
// Create object of the Dog class
Dog doggy;
// Calling members of the base class
doggy.jump();
doggy.sit();
// Calling member of the derived class
doggy.bark();
return 0;
}Output
I can jump! I can sit! I can bark! Woof woof!!
Multiple Parameters Conversion Constructor
Let us look at the example below to understand this case –
#include <iostream>
using namespace std;
class PrepInsta
{
int x, y;
public:
void display(){
cout << "The values are: " << x << " and " << y << endl;
}
// parameterized constructor
PrepInsta(int a, int b){
x = a;
y = b;
}
};
int main()
{
PrepInsta p1(50, 50);
p1.display();
// Parameterized conversion constructor invoked using multiple variables
p1 = {100, 200};
p1.display();
PrepInsta p2 = {200, 200};
p2.display();
return 0;
}Output
The values are: 50 and 50 The values are: 100 and 200 The values are: 200 and 200
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