Question

Well suppose there is a function

void fun(const MyStructure& argu1 = MyStructure(), MyStructure& argu2 = Mystructure())

argu2 isn’t const because I want to modify its value in the function.

To call the function:

MyStructure a; 
MyStructure b; 
fun(a,b);

The build succeeds in windows but fails in Linux and the error is

default argument for parameter of type 'MyStructure&' has type 'MyStructure'

But the build succeeds both in windows and in linux if I remove the second default argument which is non-const… Can anybody tell me why and how to solve it?

Answer 1

You can use overloading to let you manually handle an optional second non-const reference argument:

void fun( MyStruct const& arg1, MyStruct& arg2)
{
    // do the real work
}

void fun( MyStruct const& arg1 = MyStruct())
{
    MyStruct arg2;  // a dummy argument that can be changed, but we'll
                    //  throw those changes away
    fun( arg1, arg2);
}