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C++ Constructors:
What are constructors?
- The constructor is a member function of a class which initialized the objects of a class. The constructor will be called automatically when an object is created.
- The constructor has the same name as of the class and it does not have any return type.
How the constructors are different from a member function?
The constructors are different from the member function in such ways like:
- Constructor can be called automatically when an object is created.
- The constructor name is same as of the class.
- It does not have the return type.
- If the constructor is not specified than the compiler will generate a default constructor.
Types of Constructors
There are two types of constructors:
- Default Constructor
- Parameterized Constructor
Default Constructor:
The default constructor is the constructor which does not accept any argument. It does not have any parameters.
Let us understand this through an example:
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#include <iostream> using namespace std; class test_construct { public: int x, y; // Default Constructor test_construct() { x = 20; y = 100; } }; int main() { // Default constructor called automatically // when the object is created test_construct t; cout << "x: " << t.x << endl << "y: " << t.y; return 1; } |
Parameterized Constructor:
- In the parameterized constructor we can pass the arguments to the constructor. The arguments will help to initialize an object when it is created.
- Define the constructor’s body then the parameters are used to initialize the object.
Let us have a look at the example:
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#include <iostream> using namespace std; class Parameterized { private: int a, b; public: // Parameterized Constructor Parameterized(int a1, int b1) { a = a1; b = b1; } int getA() { return a; } int getB() { return b; } }; int main() { // Constructor called Parameterized p1(20, 35); // Access values assigned by constructor cout << "p1.a = " << p1.getA() << ", p1.b = " << p1.getB(); return 0; } |
What are the uses of Parameterized Constructor?
- They are used to initialize the various data elements of different objects with different values when they are created.
- This constructor is used to overload constructors.