non-member function cannot have cv-qualifier

Question

While writing the following function abs, I get the error:

non-member function unsigned int abs(const T&) cannot have cv-qualifier.

template<typename T> inline unsigned int abs(const T& t) const {     return t>0?t:-t; } 

After removing the const qualifier for the function there is no error. Since I am not modifying t inside the function the above code should have compiled. I am wondering why I got the error?

Answer 1

Your desire not to modify t is expressed in const T& t. The ending const specifies that you will not modify any member variable of the class abs belongs to.

Since there is no class where this function belongs to, you get an error.

Answer 2

The const modifier at the end of the function declaration applies to the hidden this parameter for member functions.

As this is a free function, there is no this and that modifier is not needed.

The t parameter already has its own const in the parameter list.