[RESOLVED] Windows API data types + LPCBYTE

[johanobrien]

Can anyone tell me what an LPCBYTE is (found reading through someones code) and how it differs from a long pointer to byte LPBYTE? It doesn't seem to be part of the windows api ...

A more general question - is there a simple reason why windows defines its own versions of the basic types (char as BYTE, short as WORD, long as DWORD).. and more importantly why you should use them?

Many thanks in advance

[NigelQ]

LPCBYTE is a const LPBYTE or a const char * (as defined in ODBCSS.H)

The API used its own defines so that it can remain consistent across all supported platforms. A WORD on a 16-bit platform, should be the same size as a WORD on a 64-bit platform (both 16-bit unsigned integers), whereas an int value is entirely different (16 vs 64).

Hope this helps,

- Nigel

[xMRi]

LPCBYTE is a const LPBYTE

This information is wrong LPCBYTE is not const LPBYTE! This makes the pointer itself constant not the value pointed to!

Even const char* is the wrong track. BYTE should be unsigned, so const unsigned char* or const BYTE * (if windows.h is included) may be a way.

PS: I know that the thread is old, but wrong information should be corrected (Just my 2 cents).

[2kaud]

Yes, I agree that wrong information should be corrected.

LPCBYTE is defined as

typedef const BYTE *LPCBYTE;

with BYTE defined as

typedef unsigned char BYTE;

Hence LPCBYTE is actually

typedef const unsigned char* LPCBYTE;

which can be changed to be

typedef unsigned char const * LPCBYTE;

which can be read from right to left as
a pointer to const unsigned char. ie a non-const pointer to const memory of type unsigned char.

If it was a const pointer to non-const memory then the definition would be

typedef BYTE * const CLPBYTE;

which, from right to left, is const pointer to non-const BYTE (unsigned char).

For a const pointer to const memory, it would be

typedef BYTE const * const CLPCBYTE;

or

typedef const BYTE * const CLPCBYTE;

ie const pointer to const BYTE data.