0

I have code:

int SomeClass::sum(int x)
{
    return x+=x;
}

int SomeClass::sum(int & x)
{
    return x+=x;
}

....

int num = 0;
int result = sum(num);

that not work. How I can use both functions and indicate which of them I want to use when I сall them?

Qewo Setner
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3 Answers3

2

You can provide two different overloads taking int& and const int&, which might somehow meet your needs...

But the whole code is a bit strange... in the function that takes the argument by value you are modifying it (+=), when it probably makes sense to only read it return x+x;. In the overload that takes the reference, you are both modifying the argument and returning the new value. That is a bit strange.

Other than that, sum is a horrible name for a function that multiplies by 2.

David Rodríguez - dribeas
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1

You can not have such functions in C++. They will have to be named differently for instance sumByCopy and sumByRef. How would you expect the compiler to decide which one are you referring to at each point?

Ivaylo Strandjev
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  • Sure we can have such functions, but we just cannot call them directly due to ambiguity, therefore, it does not make sense to provide them in this way, but not because we cannot have such functions together in C++. – taocp Apr 09 '13 at 15:24
  • @tacp: ... and you can even call them! `const int i = 10; sum(i);`, or `int i = 10; static_cast(f)(i); static_cast(f)(i);`... – David Rodríguez - dribeas Apr 09 '13 at 15:28
0

You can overload in this way, it will compile OK if you do not call any of them directly. However, it will cause ambiguity when you call sum(num). Therefore, it is no sense to provide those overloads of a function since we cannot directly call none of them. This kind of overloads is useless and violates good practice.

taocp
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