What is function in C++


                               

Function

Function is a program with group of statements, which performs specific operations. the function main() is special and important function in c,c++,java.
The basic advantage of function is to reduce the size of program by calling and using them at different position.

Syntax :
Main()
{
//void show();
Show()      //function call
return 0;
}
void Show()
{
------------Function body
**********
}

When function is called control transfer to first statement in the function definition.
The other statements in function definition are executed and control returns to the main program.

For writing a function we need
A function declaration
A function call.
A function definition.

What is function declaration ?

This refer to function prototyping before using function it has to be declare, It is same as declaring a variables.
A function may be declare in  int main() function or in class.
Syntax:  return type  function name(argument list)
The function prototype gives details to the compiler as number and type of arguments, return type ,function name.
When function is call compiler ensure that proper argument are passed and return value is treated as correctly.
There is major difference between prototyping between C and C++ while C++ makes the prototyping essential ANSIC makes its optional.


What is function call ?

We can call function directly or indirectly.
We have to pass actual arguments to the function
The argument which we pass should match with formal parameter which are declare into function.
The data type and order should also be match.

Syntax :: function name (actual argument list)
                 Area(10,5);

What is function definition ?

The function definition contains actual code of programs.
Function definition consist of 2 parts.
i)                    Function Header
ii)                  Function body

Syntax ::
Return function name (formal parameter)
{
-          - - -
-          - - - -
}


Program factorial of number


#include<iostream>
int main()
{
Void fact (void)
fact ();
return 0;
}

Void fact()
{
int i ,num,f=1;
cout<<”Enter the number : ”;
cin>>num;
for(i=1;i<=num;i++)
{
f = f * i ;
}
Cout<<”Factorial is : ”<< f ;

}

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