Recursion

Recursion is a technique in which a functions calls itself.

Factorial Example

Factorial is the multiplication of each numbers from 1 to N. For example 4 factorial = 4 * 3 * 2 * 1 = 24.

Let's look at the following example:

using System; namespace csharp { class Program { static void Main(string[] args) { Console.Write(calcFactorial(4)); } static int calcFactorial(int num) { if (num == 0) { return 1; } return num * calcFactorial(num - 1); } } }

Output:

24

At line 19 the function calls itself but with decremented value as argument.

The recursion should eventually end which is done at line 16.

Stack Overflow Exception

Recursion must have an end condition so an endless self calling is prevented.

If not stack overflow exception is thrown.

The following example causes such:

namespace csharp { class Program { static void Main(string[] args) { recursiveFunc(); } static void recursiveFunc() { recursiveFunc(); } } }