Can anyone tell me why this doesn't work?

[Sythen]

MainGame.cpp

#include <iostream>
#include "functions.h"
using namespace std;


int main()
{
    int attack;
    Leviathan(attack);
    cout << "Attack: " <<attack << endl;
    system("pause");
    return 0;
}

functions.h

int Leviathan(int attack);

MonsterList.cpp

int Leviathan(int attack)
{
    attack = 5;
    return attack;
}

I'm trying to get attack to return from MosterList.cpp to MainGame.cpp as 5.
But it is always 0.


How do I get it to return what I changed in the MonsterList.cpp?

[Raigne]

You are not assigning a value to attack.
Leviathan should be

void Leviathan( int& attack )
{ attack = 5;
}

 Or 
int Leviathan ( )
{
  return 5;
} // assign with = i.e. int attack = Leviathan();

[Elysia]

When you pass in your variable attack into Leviathan, a new local variable to the function Leviathan is created and the value you passed in (the value in the attacked variable) is copied over.
Hence, any changes you make to the attack is lost when the function ends since local variables are then disposed.
If you instead make it a reference (Raigne provided the syntax), you tell the compiler that the variable attack in Leviathan shall not be a local variable, but instead should be same variable that you pass in.
So, since you pass in attack, the variable attack in Leviathan refers to the variable attack in main (they need not have the same name).

[rodrigorules]

I think the responses to his question have gotten far too complicated. (it's clear the original poster does not yet understand references &, etc etc, so I hope this explanation is much clearer) (Even though the OP is using the function as though it were accepting a reference)

You called a function called 'Leviathan', it returned the number 5, but you did not save it anywhere.

Replace the following line in MainGame.cpp:

    Leviathan(attack);

to

    attack = Leviathan(attack);

What this does is store the value that is 'returned' by the function Leviathan where you want it, which is in the variable 'attack'.

[Elysia]

I think the responses to his question have gotten far too complicated. (it's clear the original poster does not yet understand references &, etc etc, so I hope this explanation is much clearer) (Even though the OP is using the function as though it were accepting a reference)

Which is precisely why attempts have been made to explain references since they're integral to the language...