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Recursive Function in C programming

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            If a statement within the body of a function calls the same function, the function is called recursive function. Actually, recursion is a process by which a function calls itself repeatedly until some specified condition has been satisfied. This process is used for repetitive computations in which each action is stated in term of previous result. Many iterative or repetitive problems can be written in this form.
               To solve a problem using recursive method, two conditions must be satisfied. They are:
1)      Problem could be written or defined in term of its previous result.
2)      Problem statement must include a stopping condition.

/*   An example of recursive function to calculate factorial of a number.*/
   #include<stdio.h>
   #include<conio.h>
     long int factorial(int n)
            {
                if(n==1)
                     return(1);
                else
                      return (n*factorial(n-1));
               }

void main()
          {
             int num;
             printf(“Enter a number:”);
             scanf(“%d”,&num);
               printf(“The factorial is %ld”, factorial(num));
               getch();
           }
Difference between Recursion & Iteration:
Recursion
1. A function is called from the definition of the same function to do repeated task.
2. Recursive is a top-down approach to problem solving; it divides the problem into pieces.
3. In recursion, a function calls to itself until some condition will be satisfied.
4. Problem could be defined in terms of its previous result to solve a problem using recursion.
5. All problems cannot be solved using recursion.

Iteration
1. Loop is used to do repeated task.
2. Iteration is like bottom-up approach, it begins with what is known and from this it contacts the solution step by step.
3. In iteration, a function doesn’t call to itself.
4. It is not necessary to define a problem in term of its previous result to solve using iteration.
5. All problems can be solved using iteration.
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