Passing by reference with templates

[antirsi96]

Hi! Could someone tell me why wouldn't this code compile when adding '<double>' after the function call?

template<class T>
T add(T& a, T& b){
 	return a + b;
}

int main() {
	int a, b;
	cin >> a >> b;
	cout << add<double>(a,b);
}

Compiler error:

cannot convert 'a' (type 'int') to type 'double&'

[LB]

Because you accidentally used int on line 7 instead of double. References cannot bind to variables of different types (though const references can bind to temporary conversions).

[antirsi96]

Oh ok. So that's why it accepts the int on line 7 if the variables are passed by value.

Thanks!