In it we can use the same function name to create functions that
perform different tasks. By using this concept we can create different
functions that have same name but take different arguments. The correct
function that will be invoked for a particular function call depends
upon the number, types and sequence of the arguments but the return
type of the function does not matter for selection.
For example (C++):
//Declarations The selection of a particular function for a particular function call is done by using following steps:
int add (int a, int b); //Prototype 1
int add (int a, float b); //Prototype 2
float add (float a, float b); //Prototype 3
int add (int a, int b, int c); //Prototype 4
cout<<add(5,10); //Uses prototype 1
cout<<add(2,10,3); //Uses prototype 4
cout<<add(6,2.75); //Uses prototype 2
cout<<add(3.75,4.5); //Uses prototype 3
of all the compiler tries to make exact match on the basis of number,
sequence and data types of arguments. If exact match is found then that
function is used otherwise next step is used.
2. If exact match is
not found, then the compile applies the following conversions or
promotions to select the appropriate function:
– char, unsigned char, short to int.
– float to double
conversions or promotions are done under the same category, like char
and int belong to same category, float and double belong to same
category etc. If it works then ok, otherwise next step is used.
the above two steps fail, then compiler tries to make built-in
comparisons to find the appropriate match. Such conversions can be:
– int to double and vice versa.
– int to float and vice versa.
These conversions are done under different categories like if we try to
convert int to double then both are falling under different category.
If using this unique match is found then ok, but if multiple matches
are found then the complier will generate error message.
4. If all the above steps fail then
compiler will try to find the match by using used-defined conversions
along with promotions and built-in conversions.
The example of function overloading in case of C++ is given below: