Thread: Difference between method overriding and overloading

Originally Posted by nancyphilips

Is the concept of method overriding different from the concept of overloading. If so how they both differ.

Function Overriding: In a child class, redefining the default behavior of an inherited function (default behavior of an inherited function is the behavior defined in the parent class for this function). For example,
class MyParent:
{
virtual Func() { print "Hello World"; }
};
class MyChild : public MyParent
{ // Default behavior of Func is (parent supplied) "Hello World"
//Redefining parent supplied behavior
Func() { Calculate equations; print equations;}
}
---------------------
Function Overloading: Has nothing to do with inheritance. This is the ability that the programming language offers you, by which you can reuse the lable name of the function to perform different tasks at different times. For example:
class MyClass
{
int MyOLFunction () { print "Hello World"; return 0;}
int MyOLFunction (int x) { print "Hello World" x number of times; return 0;}
int MyOLFunction (char a) { print "Hello World"; print a; return 0;}

//Note: The following are not function overriding, and will generate compile time error
long MyOLFunction () { print "Hello World"; return 0;} // Error
char MyOLFunction () { print "Hello World"; return 0;} // Error
};

Overriding means modifying or enhancing the method implementation in derived class.
Overloading means class have more than one method having same name but different implementation or different number of input parameters with different return type.

* Overloading deals with multiple methods in the same class with the same name but different signatures

* Overriding deals with two methods, one in a parent class and one in a child class, that have the same signature

* Overloading lets you define a similar operation in different ways for different data

* Overriding lets you define a similar operation in different ways for different object types

when ever we want code refinement(means some changes in method body) then that time we r using overloding

when ever we want cod replacement(means totally changes body) then that time we r useing overriding

i need the answer for the title

differences are as follows:
OVERLOADED OVERRIDING
1.)arguments- can change must not change

2.)exceptions-can change cant change except for covariant returns

3.)invocation-reference type determines which overloaded version is selected at compile time .the actual method tht is invoked is still svirtual method invocation that happens at runtime but the compiler will already know the signature of the method to be invoked .so at the runtime the argument match will already have been nailed down
but in overriding object type determines which methjod is selcted happens at runtime

I have one confusion..

If we have a method in superclass having signature int abc(int a, int b)

and we also defined a method in the subclass having method signature int abc(int c)
then what this phenomenon will be called. This is not overriding. Is this method overloading for subclass.

any help will be appreciable..

In java,c++ there are two type of polymorphism: compile time polymorphism (overloading) and runtime polymorphism (overriding).

When you override methods, JVM determines the proper methods to call at the program’s run time, not at the compile time. Overriding occurs when a class method has the same name and signature as a method in parent class.

Overloading occurs when several methods have same names with

* Overloading is determined at the compile time.
* Different method signature and different number or type of parameters.
* Same method signature but different number of parameters.
* Same method signature and same number of parameters but of different type


Example of Overloading
int add(int a,int b)
float add(float a,int b)
float add(int a ,float b)
void add(float a)
int add(int a)
void add(int a) //error conflict with the method int add(int a)

Example: Overloading


Class BookDetails{
String title;
String publisher;
float price;

setBook(String title){
}
setBook(String title, String publisher){
}
setBook(String title, String publisher,float price){
}


}

Example: Overriding

class BookDetails{
String title;

setBook(String title){ }
}

class ScienceBook extends BookDetails{

setBook(String title){} //overriding

setBook(String title, String publisher,float price){ } //overloading

}

Overriding - same method names with same arguments and same return types associated in a class and its subclass.

Overloading - same method name with different arguments, may or may not be same return type written in the same class itself.

_____________________________
Cegonsoft

if the super class and sub class have the same name and signature then this is called METHOD OVERRIDING.

Method overriding and overloading is the different types of polymorphism.
Method overloading is compile time polymorphism. In overloading function name is same but signature is different.we can say that return type & parameter list should be different.
Method overriding is runtime polymorphism. In overriding function name & signature are same.It is implemented using virtual & override kyword

Originally Posted by sudhansulenka

overlaoding:functions having same name and same signature.It is a run time polymorphism.Eg: virtual function
overlaoding:function having same name but different signature.It is a compile time polymorphism.Eg: operator overloading and function overloading.

In the above explanation, u wrote function overloading. While any1 is function overriding.
So, pls correct the error where function overloading will come and where function overriding.