Recursion

http://www.tutorialdost.com/C-Programming-Tutorial/15-C-Recursion.aspx

Recursion in C

When a function calls itself from its body is called Recursion.

Advantages

• Reduce unnecessary calling of function.
• Through Recursion one can Solve problems in easy way while its iterative solution is very big and complex.

Disdvantages

• Recursive solution is always logical and it is very difficult to trace.(debug and understand).
• In recursive we must have an if statement somewhere to force the function to return without the recursive call being executed, otherwise the function will never return.
• Recursion takes a lot of stack space, usually not considerable when the program is small and running on a PC.
• Recursion uses more processor time.

Example : C program to calculate factorial using recursion

 #include<stdio.h>

 long Factorial(int);

 void main()
 {
              int num;
              long fact;

              printf("\n\tEnter any positive number : ");
              scanf("%d",&num);

              fact = Factorial(num);

              printf("\n\tThe Factorial of %d is %ld",num,fact);

 }

 long Factorial(int num)
 {
              if (num == 1)
  return 1;
              else
  return num*Factorial(num-1);
 }

   Output :

              Enter any positive number : 
              The Factorial of 10 is 3628800