Pass by reference (&) super confusing!

[ahswong]

The correct answer is actually 2 0 0.
I understand why 2 is the answer but i dont understand the 0 0. Can someone please explain it? Im ready to pull my hair out.

  #include <iostream>
using namespace std;

void doSomething(int&);

int main()
{
int x = 2;

cout << x << endl;
doSomething(x);
cout << x << endl;
return 0;
}

void doSomething(int& num)
{
num = 0;
cout << num << endl;
}

[jonnin]

Pass by reference ...
cout x, its 2, ok.
call dosomething. Num is now x. Its the same thing.
change num to 0. This changes x to 0, because num = x because num is a reference to x.
cout num, which is x, which is zero.
exit function.
cout x, which is 0, again.

[ahswong]

can you explain what's the different between pass by reference and pass by value.

[Chervil]

what's the different between pass by reference and pass by value.

"By reference" passes the actual variable itself. "By value"
passes a copy of the variable.

See the tutorial where it is covered in more detail:
http://www.cplusplus.com/doc/tutorial/functions/