query about recursion function

Question

using System; namespace InterviewQuestionPart4 { class Program { static void Main(string[] args) { Console.WriteLine( Please Enter a Number); //read number from user int number =Convert.ToInt32(Console.ReadLine()); //invoke the static method double factorial = Factorial(number); //print the factorial result Console.WriteLine( factorial of+number+=+factorial.ToString()); } public static double Factorial(int number) { if (number == 0) return 1; return number * Factorial(number-1);//Recursive call } } } in the above program when condition is satisfied then its should return 1as output then how the result is return?

Ehsan Sajjad · Answer

The q is returned when the last recursive call is reached at that time the returned 1 is multiplied with the number variable from the previous call stack and keeps going to multiply until the recursion whole stack is executed. For example user input 5 as numbers then the call would be like: return 5 * Factorial(5-1); // this will cause to call Factorial method again return 4 * Factorial(4-1); // this will cause to call Factorial method again return 3 * Factorial(3-1); // this will cause to call Factorial method again return 2 * Factorial(2-1); // this will cause to call Factorial method again return 1; // this will cause to call Factorial method again Now the recursive call will be backtracked so 1 is returned from last recursive call which is then multiple with previous stack call which will be 2*1 and then result will be returned to the call previous than this which will be 3*2 and this will go on until the first call is reached which return 5 * Factorial(5-1) and the end result will be returned to the Console.WriteLine call parameter. I hope it helps you.