Recursion Problem

[bpurificacion]

Hi i'm currently trying to do a recursion homework assignment that does the factorial of any number the user inputs. I'm having trouble with getting the number the user inputs, and putting it in the function. Any suggestions?

#include <iostream>
using namespace std;

int fact(int n);

int main()
{
char ch;
int choice;

do
{
cout << "Pick any positive integer: " << fact(choice);
cin >> choice;

cout << "Press 'y' to run again, any other key to quit:";
cin.ignore();
cin.get(ch);
} while (ch =='y' || ch =='Y');

return 0;
}

int fact(int n)
{
int answer;

if (n==1)
return 1;
else
answer = fact(n-1) * n;
return answer;
}

this is what i have so far. and it says i have an "uninitialized local variable 'choice' used" in the bolded area.

[Laharl]

Right. Your current setup displays "Pick any positive integer." and then calculates the factorial of a number the user hasn't displayed yet! Move fact(choice) to a cout statement that's after the user has input the value and this will work fine.

[bpurificacion]

Thanks! that fixed the problem. I couldn't even do that for something so easy and so simple. thats a beginner for you...

[JosAH]

Not that it matters much but change your if statement:

if (n == 1)
 

to this:

if (n < 1)
 

because those stupid users like to input silly negative numbers and you don't
want your stack to overflow.

kind regards,

Jos