* --Originally published at Ervin Schlamme´s blog*

In this #wsq06 we are going to learn how to create a factorial calculator. First of all we need to know what is a factoria operation (n!), which is the product of every number in a sequence in which n+1 is achieved. For example:

5!=1*2*3*4*5=120

The code for this operation is this one:

#include <iostream>

#include <string>

using namespace std;

int factorial (int n) // create a function of type integer that give the factorial value of n (n!)

{

if (n == 0)

{

return 1;

}

else

{

int recursion = factorial (n – 1);

int answer = n * recursion;

return answer;

}

}

int main ()

{

repeat:

string again;

int number;

int answer;

cout << “type number” << endl;

cin >> number;

answer = factorial (number);

cout << “The value for n! = ” << answer << endl; // prints the answer

ask:

cout << “Do yu want to try again?” << endl;

cin >> again;

if (again == “yes”) goto repeat;

if (again == “no”)

{

cout << “Come back soon!” << endl;

}

else

{

cout << “That is not a valid answer, try again simply typing yes or no.” << endl;

goto ask;

}

return 0;

}

in which the result must be like this:

I made a correction on “come back soon” on the code I just showed, in the image it says “Come back soos!”.

Oh, and by the way I used the next #masterytopics:

#masterytopics25

#masterytopics26

#masterytopics27

#masterytopics10

#masterytopics06

#masterytopics07