Thread: My function's being dumb.

Hi.

I'm trying to write a C++ program for class that'll take two numbers and see if one is a multiple of the other. I'm doing this with a function and by repeatedly subtracting the bigger number by the smaller one until the value left over is "0" or lower.

However, I am running into quite a stupid problem. I can get it to display the left over number and it'll either output "0" or lower letting me know that the code worked.

As soon as I put in an "if" statement and a "cout << " to display either "True" or "False", it just... resets the number back to '0'? wtf?

This is what I have so far:

Code:

//Page 274
//Question 6.20


#include <iostream>

using namespace std;

int multiple(int a, int b){
    int c;
    if(b>a){
            c = b;
    
            while(c>0){
                       c-=a;
            }
    }else if(b<a){
            c = a;
            
            while(c>0){
                       c-=b;
            }
    }
    
    return (c);
    
}

int main(){
    int numone, numtwo;
    int ismultiple;
    
    cout << "Enter a number: ";
    cin >> numone;
    cout << "Enter another number: ";
    cin >> numtwo;
    
    ismultiple = multiple(numone, numtwo);
    
    if(ismultiple=0)cout << "True.\n";
    
    cout << ismultiple << endl;
 
    return 0;   
}

Now comment out that "if(ismultiple=0)cout << "True.\n";" line and the code works. It displays the right number.

Am I doing something wrong?

'c' does.

It starts off with 'c' being assigned the bigger number, and then it's subtracted by the smaller number until it's 0 or less.

Originally Posted by King Mir

As written, it will just return a random number, likely 0 or the value of a variable from a previously called and returned function.

The thing is though, it's not.

Here's some output:

Code:

Enter a number: 3
Enter another number: 5
0

Now if I remove that one if statement with the cout in the end, it looks like this:

Code:

Enter a number: 3
Enter another number: 5
-1

Now I want to take that -1 and go "Oh! It's false!", anything below 0. If it's 0 though, then go "Oh! It's true!"



Why would that one practically irrevalent line screw up the entire thing? It's not changing anything...

Am I missing something here? Surely you just need to use the % operator?