How to understand this #define statement in C++ class definition?

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I met this class definition in my study:

class style{
DWORD getExtWindowStyle();
HWND  getWindowOwner();
DWORD getWindowStyle();

BOOL maximizeButton;
BOOL minimizeButton;
BOOL helpButton;
BOOL systemMenu;
BOOL title;
BOOL ScrollBars;
BOOL owned;
int  border;
int  edge;
BOOL clipSiblings;
BOOL alwaysOnTop;
BOOL acceptFiles;
BOOL toolWindow;
int  windowType;

#define CHILD0
#define POPUP1
}

What is the purpose of these two #define statements? try to get more insight from C++ gurus here.

What I have tried:

I know how #define statement works, does it mean they define some macro inside this class?

Posted 19-Jun-21 9:50am

Southmountain

Updated 19-Jun-21 10:26am

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KarstenK 20-Jun-21 3:22am

Use such define with great care, because compilers arent good to yell at errors, so you main earn strange errors. Better is to think about other solutions like const values.

2 solutions

Solution 2

Quote:
How to understand this #define statement in C++ class definition?

As is in this code, it define 2 names that does nothing.
But such defines are usually used for conditional compilation.
Preprocessor directives - C++ Tutorials[^]
C/C++ Preprocessors - GeeksforGeeks[^]

Posted 19-Jun-21 10:26am

Patrice T

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Southmountain 19-Jun-21 16:34pm

so from the point where #define statement is, the defined macro is effective for conditional compilation.

Patrice T 19-Jun-21 17:07pm

Only rest of code can tell you.

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Greg Utas · Accepted Answer · 2021-06-19T10:16:00

Solution 1

You could call them macros, but all they define is the two names, no different than an #include guard. Somewhere there is probably another preprocessor directive that says

C++

#ifdef CHILD0
   // code to be conditionally compiled
#endif

Macro names are global and do not belong to a specific class or namespace.

Posted 19-Jun-21 10:16am

Greg Utas

Updated 19-Jun-21 10:18am

v2

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Southmountain 19-Jun-21 16:32pm

your explanation makes sense to me now. thank you for your time!