In this article, we are going to talk about Recursion and Recursive Methods in C#. Furthermore, we will learn how to use recursive methods and how they differ from the regular methods.

For the complete navigation of this series check out: C# Back to Basics.

If you want to download the source code for our examples, you can do that from here Recursive Methods in C# Source Code.

So what is recursion?

Recursion is a concept in which method calls itself. Every recursive method needs to be terminated, therefore, we need to write a condition in which we check is the termination condition satisfied. If we don’t do that, a recursive method will end up calling itself endlessly.

Example 1: Create an application which calculates the sum of all the numbers from n to m recursively:

Recursion and Recursive Methods

Code Explanation

The method CalculateSumRecursively is our recursive method that calculates the sum of the numbers from n to m. The first thing we do is to set our sum to the value of n. Then, we check if the value of n is less then the value of m. If it is, we increase the value of n by 1 and add to our sum a result of the same method but with the increased n. If it is not, we just return the value of the sum variable.

The C# will reserve a memory storage for every recursive method so that the values from the previous method are not overridden.

So let’s see our example through the diagram:

Graph Recursion and Recursive Methods

Additional Example

Let’s practice some more with the Example2: Create an application which prints out how many times the number can be divided by 2 evenly:



Now we have a good knowledge of recursion and recursive methods.

In the next post, we are going to talk about arrays, how to use them and about different types of arrays.

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