"unexpected in macro definition"

Question

I wrote

#ifndef Header1.h
#define Header1.h

class Complex
{
   [...]
};

#endif

in my project (Visual Studio 2010) and I get an Error C2008: '.' : unexpected in macro definition. I don't understand what the problem is with "Header1.h" or how to fix it.

The error message is pretty clear... there's nothing we can do apart from restate it - you can't used `.` in a macro name. — JoeG, Nov 05 '13 at 19:59
It wasn't intended in that tone. I'll edit it. Can't edit it, I'll delete it. — kfsone, Nov 05 '13 at 20:15
The error message was indeed very clear, but I'm a beginner, and didn't know about the rule. — Eutherpy, Nov 05 '13 at 20:17

score 4 · Accepted Answer · answered Nov 05 '13 at 19:59

4

Don't use the . use an _ instead

#ifndef HEADER1_H
#define HEADER1_H

class Complex
{
   [...]
};

#endif

answered Nov 05 '13 at 19:59

Montaldo

863
8
16

score 2 · Answer 2 · edited May 23 '17 at 12:29

You need to use an identifier here:

#ifndef Header1.h
        ^^^^^^^^^

and they can not include . in them, we can see this from the draft C++ standard section 16 Preprocessing directives paragraph 1 which includes the following grammar:

# ifdef identifier new-line groupopt
        ^^^^^^^^^^
# ifndef identifier new-line groupopt
         ^^^^^^^^^^

typically include guards are all caps and an underscores:

 #ifndef HEADER1_H

score 1 · Answer 3 · answered Nov 05 '13 at 19:59

1

Macro names can't contain periods. Rename it to Header1 or Header1h.

As an aside, it's standard for most macros to be ALL_UPPERCASE.

answered Nov 05 '13 at 19:59

Collin Dauphinee

13,664
1
40
71

score 1 · Answer 4 · answered Nov 05 '13 at 19:59

1

A macro name should not contain a dot. You'd better use

#ifndef HEADER1_H
#define HEADER1_H

...

#endif

answered Nov 05 '13 at 19:59

pvoosten

3,247
27
43

"unexpected in macro definition"

4 Answers4