12th HSC free notes of c++ language part 2. Theory

 Explain the concept of function overloading with example .

The use of same function name to create function that perform a variety of different tasks is called as function overloading .
Overloading refers to the use of same thing for different purpose .
Function overloading or function polymorphism , is an example of compile time polymorphism .
Using the concept function overloading , create a family of function with one function name but with different argument lists.
The function would perform different operation , depending on argument list in function call.
The correct function to be invoked is determined by checking the number and the type of the argument and not on the function type .
When a function is called , the compiler first matches the prototype having same number and types of arguments and then calls appropriate function for execution . A best match must be unique.

Pointers :
• A pointer is a variable which hold the memory address of another variable
• * operator is use to declear pointer in c++.
• It takes the form as :
• Datatype *variable name ;
• E.g. int *ptr:
• The above declearation will create a variable ptr which is a pointer variable and which will point to a variable whose datatype is integer.
• The data type of ptr is not integer but datatype of variable which ptr will point is integer .

Advantages of pointer :
• It allows to pass variable array ,function, string, structure, object as function arguments .
• It allow to return structured variable from functions.
• It support dynamic allocation and deallocation of memory segment .
• By using pointer variable can be swapped without physically moving them
• It allow to establish link between data elements or objects.

Call by value :
• Pointer is a variable which hold the address of another variable.
• * operator are used to declear pointer .
• The use of pointer in a function definition may be classified into two group :
Call by value.
Call by reference .
• Call by value :
• When the portion of the program invokes a function control will be transfer from main function to the calling function and the value of actual argument is copied to the function .
• Within function the actual value may be altered or changed.
• When the control is transferred back from function to the program, altered values are not transeferred back this type of passing formal arguments to the

Call by reference :
• Call by reference :
• In call by reference when the function is called by a program the address of actual argument are copied on to the formal arguments i.e.formal and actual argument referring same memory location .
• Therefore change in value of formal argument affect the value of actual arguments
• The content of variable that are alter within thee function are return to calling portion of program in alter form.