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c++pointersreferenceconstants
zLeon
zLeon

Reputation: 137

Passing const value by reference

Let's say I have this program:

const int width = 4;

void test(int&){}

int main() {
    test(width);
}

This will fail to compile. I notice that constant values ( also enumeration constants ) with names ( such as width ) cannot be passed by reference. Why is that so?

Upvotes: 0

Views: 119

Answers (2)

Kippi
Kippi

Reputation: 514

Passing by reference allows us to change the actual object. If an object is defined as const, it cannot be changed. That is exactly what const means - it's constant.

Upvotes: 0

David Schwartz
David Schwartz

Reputation: 182753

Imagine this:

void test (int& j) { j++; }

If test does change the value of the thing referenced, clearly we can't call it with a const parameter. And if it doesn't, why does it take its parameter by non-const reference?

Upvotes: 11

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