Could someone help me with this simple project?

[smerfguy2]

Hello, I recently purchased a book in C++ and one of the exercises is to create a simple factorial function. All it is supposed to do is take all the whole numbers leading up to another number and multiply them together. For example 5:
1 * 2 * 3 * 4 * 5 = 120
I can't figure out for the life of me what I am doing wrong. I know I am a total rookie but some help would be appreciated thanks.
My code looks like this:

#include <iostream>
#include <math.h>
using namespace std;

int calc(){
    int n;
    int x;
    int total;
    cout << "Enter a number to be factorialized to\n";
    cin >> n;
    for(x = 1; x <= n; x++){
    total = x * x++;
    cout << total << endl;
        }
}



int main()
{

calc();
}

When I run this I get the output
1
9
25

[LB]

There is no reason to include math.h ;)

The issue is misunderstanding the ++ operator (and another few things, but this first) - when you write var++ is makes a copy of the var, increments the original, and then gives back the copy to the expression (aka the old value), so your code is squaring a number. When you do ++var it simple increments it and returns it so you get the new value.

The other issue is, total serves no purpose because eventually you just assign n * (n+1) to it without considering its previous values. Perhaps you meant total *= x++ ?

[smerfguy2]

Thanks but I'm still lost. I tried correcting what u said and then some but I still can't get it to work :|
Do you have any suggestions on how I could actually get the correct calculation down? I'm pretty sure that just x * (x+1) isn't the correct way now that I look closer. Every time 1 is added to x I need to multiply that new version of x to x++. Like if it is 5 I need it to be multiplied by 6. Thanks for your help though.

[LB]

Like I (previously erroneously) suggested, did you try total *= x?

[smerfguy2]

Yes and I get 4 very long numbers. Unless I am using it in the wrong spot, which I probably am.... Like I said, I'm a rookie! This is what the code looks like:

#include <iostream>
using namespace std;

int calc(){
    int n;
    int x;
    int total;
    cout << "Enter a number to be factorialized to\n";
    cin >> n;
    for(x = 1; x <= n; x++){
    total *= x++;
    cout << total << endl;
        }
}



int main()
{

calc();
}

[LB]

Remove the ++ from line 11, you're already incrementing x on line 10.

[smerfguy2]

Thanks but I still get the same result :( The exercise is in the functions section of the book so maybe I should have to call another function or something?

[long double main]

You didn't initialize total, so it has a garbage value the whole time. (initialize it to 1)

Your calc function says it returns an int, but it doesn't.

[smerfguy2]

I feel so stupid right now... That should be so obvious to me.

[smerfguy2]

Thank you it worked :D

[long double main]

Just make sure you don't enter anything above 12. :)