Recursion
è
When any called function in turn calls another function a process of chaining occurs.
è
When function calls itself the process is known as recursion.Recursion is a special case
of this process , where a function calls itself.
Ex,
void
main()
{
printf(“\n
This is recursive main()”);
main();
}
Here the main() calls itself and
the message written in printf() will display. Execution is terminated abruptly
; otherwise the execution will continue indefinitely.
The calculation of factorial of
given number can be easily find out using recursion. Factorial of a number n is
expressed as a series of repetitive multiplication as shown below.
Factorial of 5 =5*4*3*2*1
= 120
Ex
#include<stdio.h>
#include<conio.h>
int fact(int);
void main()
{
int n,f;
clrscr();
printf("\n Enter any number : ");
scanf("%d",&n);
f=fact(n);
printf("\n Factorial of %d = %d",n,f);
getch();
}
int fact(int n)
{
if(n==1)
{
return(1);
}
else
{
return(n*fact(n-1));
}
}
The execution of recursion is as
follw:
Suppose n=5 then,
First checks if(n==1)
since the value of n in not 1 , the statement
return(n*fact(n-1)); will execute
as :
return(5*fact(4)); 5*24
=120
return(4*fact(3)); 4*6
=24
return(3*fact(2)); 3*2
=6
return(2*fact(1)); 2*1
=2
When n=1 then returns 1 to the last
call of function.
Posted By : Ruchita Pandya
