References Exercise 4: Multiple “Return” Values via References
Sometimes we have a function that we wish could return multiple values. For example, we might have a division function that should return a quotient and a remainder.
Ah, but C++ doesn't allow multiple return values!
In fact, there are ways to return multiple values, such as using
std::tuple, a bit like you would in Python.
Actually, it's really easy to use tuples in Python for multiple return values, but pretty clumsy to use them in C++.
We're really supposed to be talking about references here, but, since we've brought up
std::tuple, the 2017 version of the C++ standard added structured bindings which makes tuples much more usable.
But it's still a ton of stuff to have to learn for just the simple task of getting two distinct values out of a function. So, let's set aside that approach for now.
References can provide a simple solution to the “two return values needed” problem.
void div(size_t a, size_t b, size_t& quo, size_t& rem)
{
rem = a;
quo = 0;
while (rem >= b) {
rem = rem - b;
++quo;
}
}
int main() {
size_t x = 24;
size_t y = 7;
size_t quotient;
size_t remainder;
div(x, y, quotient, remainder);
cout << x << " " << y;
cout << " " << quotient;
cout << " " << remainder;
}
Oh, I see! You can pass in a reference to a variable and the function can fill in a value for that variable.
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Now you're getting it!
References are awesome!
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I know, right? It's amazing that we got this far into the semester without using them!
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Okay, that was good work, but we're not done yet! Let's head back up to the parent page to see our progress and maybe take a break!
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