object-orientation question
Author
here is my problem.
in my program,there are 4 class:winmain,player,raycaster,lookuptable.
either player or raycaster will contain a lookuptable in them in order to access information stored in lookuptable,so what i did is
//class player
#include lookuptable
//class raycaster
#include lookuptable
and in winmain head file of both player n raycaster will be included.but when i try 2 compile it.it gives me a error saying type lookuptable redefinition.i image the reason for that is both player and raycaster has lookuptable in it,as a result in winmain,compiler will try to declare lookuptable twice.
can anyone tell me a solution 2 that plz?thx.
put this at the start of the lookuptable header:
#ifndef __LOOK_UP_TABLE_HEADER
#define __LOOK_UP_TABLE_HEADER
and this at the end:
#endif // __LOOK_UP_TABLE_HEADER
when the file is first encountered, it will see that __LOOK_UP_TABLE_HEADER hasn''t been defined, so it will include everything between the #ifndef and #endif. However, if the header is opened again, it will see that __LOOK_UP_TABLE_HEADER has already been defined (by the first include), and therefor it will skip the code as it is already available.
#ifndef __LOOK_UP_TABLE_HEADER
#define __LOOK_UP_TABLE_HEADER
and this at the end:
#endif // __LOOK_UP_TABLE_HEADER
when the file is first encountered, it will see that __LOOK_UP_TABLE_HEADER hasn''t been defined, so it will include everything between the #ifndef and #endif. However, if the header is opened again, it will see that __LOOK_UP_TABLE_HEADER has already been defined (by the first include), and therefor it will skip the code as it is already available.
or, if you are using VC++ you can put in the compiler command:
#pragma once
somewhere in each header
#pragma once
somewhere in each header
quote:Original post by Symphonic
or, if you are using VC++ you can put in the compiler command:
#pragma once
somewhere in each header
#pragma once is also implemented in GCC 3.4.0.
put
#ifndef SOMEHEADERDEFINITION
#define SOMEHEADERDEFINITION
#endif
for every header file you have. not just lookup table.
#ifndef SOMEHEADERDEFINITION
#define SOMEHEADERDEFINITION
#endif
for every header file you have. not just lookup table.
quote:Original post by MENTAL
#ifndef __LOOK_UP_TABLE_HEADER
#define __LOOK_UP_TABLE_HEADER
You might want to stay away from defines or identifiers starting with double underscores, those are used by the compiler for internal names (as are names starting with a single underscore and a capital letter). Chances are no compiler uses __LOOK_UP_TABLE_HEADER, but if you use heaps of these you might at some point run into some weird, hard to find bugs.
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