A simple example of recursion. : Method Recursion « Class « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Class
3. Method Recursion

A method can call itself is called recursion.

using System; 
 
class Factorial {  
  // This is a recursive function.  
  public int factR(int n) {  
    int result;  
  
    if(n==1) return 1;  
    result = factR(n-1) * n;  
    return result;  
  }  
  
  // This is an iterative equivalent.  
  public int factI(int n) {  
    int t, result;  
  
    result = 1;  
    for(t=1; t <= n; t++) 
       result *= t;  
    return result;  
  }  
}  
  
class MainClass {  
  public static void Main() {  
    Factorial f = new Factorial();  
  
    Console.WriteLine("Factorials using recursive method.");  
    Console.WriteLine("Factorial of 3 is " + f.factR(3));  
    Console.WriteLine("Factorial of 4 is " + f.factR(4));  
    Console.WriteLine("Factorial of 5 is " + f.factR(5));  
    Console.WriteLine();  
 
    Console.WriteLine("Factorials using iterative method.");  
    Console.WriteLine("Factorial of 3 is " + f.factI(3));  
    Console.WriteLine("Factorial of 4 is " + f.factI(4));  
    Console.WriteLine("Factorial of 5 is " + f.factI(5));  
  }  
}

Factorials using recursive method.
Factorial of 3 is 6
Factorial of 4 is 24
Factorial of 5 is 120

Factorials using iterative method.
Factorial of 3 is 6
Factorial of 4 is 24
Factorial of 5 is 120