c# interview questions and answers

Part 5 Recursive function c# example

Link for code samples used in the demo
http://csharp-video-tutorials.blogspot.com/2013/10/part-5-recursive-function-c-example.html

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What is a recursive function in c#? Give an example. This is a common c# interview question.
A recursive function is a function that calls itself. Let’s look at an example of computing factorial of a number with and without recursion.

Program to compute factorial of a number without using recursion.
public class Program
{
public static void Main()
{
// Prompt the user to enter a number
Console.WriteLine(“Please enter a number”);
// Read the number from the console and convert to int
int userNumber = Convert.ToInt32(Console.ReadLine());
// Call Factorial function and pass the user entered number to it
double factorial = Factorial(userNumber);
// Print the factorial
Console.WriteLine(“Factorial of ” + userNumber.ToString() + ” = ” + factorial.ToString());
}

public static double Factorial(int number)
{
// ZERO factorial is 1, so return 1 if number is ZERO.
if (number == 0)
return 1;

double factorial = 1;

// Compute the factorial using a for loop
for (int i = number; i ]= 1; i–)
{
factorial = factorial * i;
}

// return the factorial of the anumber
return factorial;
}
}

Program to compute factorial of a number with recursion.
public class Program
{
public static void Main()
{
// Prompt the user to enter a number
Console.WriteLine(“Please enter a number”);
// Read the number from the console and convert to int
int userNumber = Convert.ToInt32(Console.ReadLine());
// Call Factorial function and pass the user entered number to it
double factorial = Factorial(userNumber);
// Print the factorial
Console.WriteLine(“Factorial of ” + userNumber.ToString() + ” = ” + factorial.ToString());
}

public static double Factorial(int number)
{
// ZERO factorial is 1, so return 1 if number is ZERO.
if (number == 0)
return 1;

// Notice that the Factorial method is calling itself here
return number * Factorial(number – 1);
}
}