Wednesday, 28 March 2018

Recursion

It is a special case of calling a function when a function calls itself again and again.It forms a chaining f calling a function.

For example:-
void main(void)
{
cout<<"Hello Dear";
main( );  /* recursive call  */
}

When executed, this program will display "Hello" on the screen indefinitely.

Another useful example of recursion is evaluation of factorial of a number. The factorial of number is expressed as a series of repetitive multiplications as,

For example:
factorial of 5 = factorial of 4 ⤫ 5 
factorial of 4 = factorial of 3 ⤫ 4
factorial of 3 = factorial of 2 ⤫ 3 
factorial of 2 = factorial of 1 ⤫ 2
factorial of 1 = 1

This statement will be transferred into recursive process in function as given below:
int factorial(int n)
{
int fact;
if(n==1)
return 1;
else
return(n*factorial(n-1));
}

Consider another example of finding value of Xy using recursion:

#include<iostream.h>
#include<conio.h>
int power(int x, int y)
{
if(y<1)
return(1);
else
return(x * power(x,--y));
}
void main( )
{
cout<<power(4,3);
getch( );
}

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