Is Xcode incorrectly correcting my const-correctness in C++?

Asked May 08 '16 at 23:08

Active May 08 '16 at 23:36

Viewed 14 times

I'm making my own string class, which I have just started, and I have typed up the following so far.

class My_String
{
    char const* characters;
    My_String(char const* _string);
    void setString(const char const* _string);
};

In my My_String method declaration, the argument has no const at the beginning, whereas my setString method declaration does.

(Note: I intend to have const at the beginning of My_String as well, however I don't in this example for comparison.)

I want a const at the beginning of the argument because I don't intend to change _string in the method.

However, Xcode gives me a warning (not error), underlining the second const (adjacent to *) of setString, with a suggestion "Duplicate 'const' declaration specifier", and offers to delete it for me.

Why does it do this? As far as I know, the 2 const serve different purposes, and therefore are not redundant.

edited May 08 '16 at 23:36

asked May 08 '16 at 23:08

Fine Man

What `init` are you talking about? Anyway, xcode is right. You have one too many `const`s. – juanchopanza May 08 '16 at 23:11
`My_String(char const* _string)`. – Fine Man May 08 '16 at 23:12
But one `const` is for constant pointing, the other is for not changing value. – Fine Man May 08 '16 at 23:13
Why duplicate? Has this question indeed been answered? – Fine Man May 08 '16 at 23:15
`const char*` is the same as `char const *`. – juanchopanza May 08 '16 at 23:15
See http://cdecl.org or the [spiral rule](http://c-faq.com/decl/spiral.anderson.html) for reading declarations. `_string` is a pointer to const char const. The reason it doesn't make much sense is because there's an extra `const`. – chris May 08 '16 at 23:15
@juanchopanza -- Then how do I make it such that the pointer is constant AND the stuff its pointing to is unchangeable? – Fine Man May 08 '16 at 23:16
Read the duplicate? Although a top level const in a function parameter gets ignored in a function signature, so you'd only need it in the implementation. – juanchopanza May 08 '16 at 23:16
So what I really want is `char const * const`? – Fine Man May 08 '16 at 23:27

Is Xcode incorrectly correcting my const-correctness in C++?

0 Answers0