How to remove the type defined by "typedef"?thx

[hercules]

Hi:
In some code , I used typedef unsigned char BOOL; /*boolean */

But in other code , I must use typedef unsigned int BOOL; /* boolean
*/

How to remove the previous typedef ?


Hercules

 

[Ben Pfaff]

In some code , I used typedef unsigned char BOOL; /*boolean */

But in other code , I must use typedef unsigned int BOOL; /* boolean
*/

How to remove the previous typedef ?

This cannot be done. However, you can use
#define BOOL unsigned char
instead of the initial typedef, then write
#undef BOOL
#define BOOL unsigned int
later to change it. Not elegant, but it should work.

 

[Scott Fluhrer]

Hi:
In some code , I used typedef unsigned char BOOL; /*boolean */

But in other code , I must use typedef unsigned int BOOL; /* boolean
*/

How to remove the previous typedef ?

You really can't remove or redefine a typedef[1]. About the best you can do
is patch around it with the CPP:

typedef unsigned char BOOL;
/* Some code here */

#define BOOL anotherBOOLtype
typedef unsigned int BOOL;

BTW: if it is all your code, why do you have to have the two distinct
definitions? Or, are you doing something like including two different
header files with the above definitions?

[1] Unless, of course, it was defined within a block. In that case, ending
the block will end the scope of the typedef, effectively removing it. I
rather doubt this applies to your code -- I just add this to make my
statement technically correct.

 

[Mark McIntyre]

Hi:
In some code , I used typedef unsigned char BOOL; /*boolean */

But in other code , I must use typedef unsigned int BOOL; /* boolean
*/

How to remove the previous typedef ?

You can't: Instead, fix your code. Two different defnitions of the
same type name is an accident waiting to happen.

 

[EventHelix.com]

You cannot undefine a type. If it is possible to change the
typedefs to #defines, you could use #undef to define the old
one.

However, I would not recommend it. It is probably better to make
code changes so that you do not have to live with these confusing
declarations.

Sandeep

 

[Dan Pop]

In some code , I used typedef unsigned char BOOL; /*boolean */

But in other code , I must use typedef unsigned int BOOL; /* boolean
*/

How to remove the previous typedef ?

The only legitimate situation where this can happen is when using two
libraries, each of them coming with its own definition of BOOL.

The right thing in such a case is to use different identifiers:

/* The typedef's must only be provided if the library headers */
/* expect BOOL to be already defined, instead of defining it */
/* themselves. */

typedef unsigned char lib1BOOL;
typedef unsigned int lib2BOOL;

#define BOOL lib1BOOL
#include <lib1.h>

#define BOOL lib2BOOL
#include <lib2.h>

#undef BOOL

/* use lib1BOOL and lib2BOOL in your own declarations */

Dan

 

[Kevin Bracey]

The only legitimate situation where this can happen is when using two
libraries, each of them coming with its own definition of BOOL.

The right thing in such a case is to use different identifiers:

/* The typedef's must only be provided if the library headers */
/* expect BOOL to be already defined, instead of defining it */
/* themselves. */

typedef unsigned char lib1BOOL;
typedef unsigned int lib2BOOL;

#define BOOL lib1BOOL
#include <lib1.h>

#undef BOOL

is required here; one is not allowed to redefine a currently-defined
identifier with a different definition.