Solving the complex problems using Recursion in C

   Another important area where functions are used is recursion. Recursion is a repetitive process here  a function calls itself.That is in a recursive process a function is calls it self. Recursion is a very important application in every where, including real life also.

             For Example if you observed in a screen recording, where a smaller window is appear as multiple windows. Like below.

Recursion in a screen recording program, where the smaller window contains a snapshot of the entire screen

               The same thing is also useful while solving a complex problem in computer science. Using the recursion the larger problem can be defined in two cases first base case and second general case. In base case the solution to the complex problem is simple and it can be solved easily. But in the general case the complex problem is divided into Small units until we reach the base case condition. Here is best example for recursion how to find factorial of a number using recursion.

The factorial of a given number is computed as using recursion is

factorial(0) = 1;

factorial(n) =n*(n-1)*(n-2)*(n-3)...............*1

       In the piece of  code the first line is the base case and the second line is the general case. In the first line the solution is comes directly, where as in the second line, the problem is reduced until the base case solution is appeared. This type of solving a problem is known as recursion. They are so may types of recursion.

Tail Recursion  

                         A recursive function is said to be tail recursive if no operations are pending to be performed to be performed when the recursive function returns to its caller. When the called function returns, the returned value is immediately returned from the calling function.

                               Tail recursive functions are highly desirable because they are much more efficient to use as the amount of information that has to be stored on the system stack is independent of the number of recursive calls.

Direct Recursion 

                    A function is said to be directly recursive if it explicitly calls itself.

Indirect Recursion

               A function is said to be indirect recursive if it contains a call to another function which ultimately calls it.