• Difficulty Level : Easy
• Last Updated : 28 Jun, 2021

It provides multiple definitions of the function by changing signature i.e changing number of parameters, change datatype of parameters, return type doesn’t play anyrole.

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• It can be done in base as well as derived class.
• Example:

```void area(int a);
void area(int a, int b); ```

## CPP

 `// CPP program to illustrate``// Function Overloading``#include ``using` `namespace` `std;` `// overloaded functions``void` `test(``int``);``void` `test(``float``);``void` `test(``int``, ``float``);` `int` `main()``{``    ``int` `a = 5;``    ``float` `b = 5.5;` `    ``// Overloaded functions``    ``// with different type and``    ``// number of parameters``    ``test(a);``    ``test(b);``    ``test(a, b);` `    ``return` `0;``}` `// Method 1``void` `test(``int` `var)``{``    ``cout << ``"Integer number: "` `<< var << endl;``}` `// Method 2``void` `test(``float` `var)``{``    ``cout << ``"Float number: "``<< var << endl;``}` `// Method 3``void` `test(``int` `var1, ``float` `var2)``{``    ``cout << ``"Integer number: "` `<< var1;``    ``cout << ``" and float number:"` `<< var2;``}`

Output:

```Integer number: 5
Float number: 5.5
Integer number: 5 and float number: 5.5```

Function Overriding (achieved at run time)
It is the redefinition of base class function in its derived class with same signature i.e return type and parameters.

• It can only be done in derived class.
• Example:
```Class a
{
public:
virtual void display(){ cout << "hello"; }
};

Class b:public a
{
public:
void display(){ cout << "bye";}
};```

## CPP

 `// CPP program to illustrate``// Function Overriding``#include``using` `namespace` `std;` `class` `BaseClass``{``public``:``    ``virtual` `void` `Display()``    ``{``        ``cout << ``"\nThis is Display() method"``                ``" of BaseClass"``;``    ``}``    ``void` `Show()``    ``{``        ``cout << ``"\nThis is Show() method "``               ``"of BaseClass"``;``    ``}``};` `class` `DerivedClass : ``public` `BaseClass``{``public``:``    ``// Overriding method - new working of``    ``// base class's display method``    ``void` `Display()``    ``{``        ``cout << ``"\nThis is Display() method"``               ``" of DerivedClass"``;``    ``}``};` `// Driver code``int` `main()``{``    ``DerivedClass dr;``    ``BaseClass &bs = dr;``    ``bs.Display();``    ``dr.Show();``}`

Output:

```This is Display() method of DerivedClass
This is Show() method of BaseClass```

1. Inheritance: Overriding of functions occurs when one class is inherited from another class. Overloading can occur without inheritance.
2. Function Signature: Overloaded functions must differ in function signature ie either number of parameters or type of parameters should differ. In overriding, function signatures must be same.
3. Scope of functions: Overridden functions are in different scopes; whereas overloaded functions are in same scope.
4. Behavior of functions: Overriding is needed when derived class function has to do some added or different job than the base class function. Overloading is used to have same name functions which behave differently depending upon parameters passed to them.

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