Const Error

[James Tabor]

Hi!

i386-mingw32-gcc -D_WIN32_IE=0x0600 -D_WIN32_WINNT=0x0501 -I./include -DUNICODE -D_UNICODE

-D__REACTOS__ -D__USE_W32API -D_HIDPI_ -D_HIDPI_NO_FUNCTION_MACROS_ -Wall -Werror
-fno-builtin -I. 
-I../../include -I../../w32api/include -pipe -march=i486 -D_M_IX86 -g -c hid.c -o hid.o
hid.c: In function `HidD_Hello':
hid.c:374: warning: duplicate `const'
make: *** [hid.o] Error 1


const PCHAR const HelloString = "Hello\n";
               ^
               | is that right?


I'm back online!
James

[Mike Nordell]

James Tabor wrote:

>   const PCHAR const HelloString = "Hello\n";
>                 ^
>                 | is that right? 
No.

Assuming PCHAR is just a (IMO basically useless) "typedef char* PCHAR;",
then "const PCHAR" would mean nothing, since you can't modify the
cv-qualification of a typedef like this (cv is C and C++ standard lingo,
meaning "const/volatile"). This is one of the reasons such stupid typedefs
are bad - the only way to make them point to a const object is by adding yet
_another_ typedef: "typedef const char* PCCHAR;" (or CPCHAR if you're into
that kind of naming :-) ), or by literally using the real type the typedef
refers to.

I suspect the well-meaning intention, but not equally informed wrt
cv-qualification and typedefs, was:

  const char* HelloString const = ...

but why anyone would do something like that instead of just

  const char HelloString[] = ...

or if wanting to make the code more obscure, harder to understand and
therefore less maintainable

  LPCSTR const HelloString = ...

I don't understand.

--
/Mike

[Thomas Weidenmueller]

James Tabor wrote:

>   Hi!
>
>  i386-mingw32-gcc -D_WIN32_IE=0x0600 -D_WIN32_WINNT=0x0501 -I./include 
>  -DUNICODE -D_UNICODE -D__REACTOS__ -D__USE_W32API -D_HIDPI_ 
>  -D_HIDPI_NO_FUNCTION_MACROS_ -Wall -Werror -fno-builtin -I. 
>  -I../../include -I../../w32api/include -pipe -march=i486 -D_M_IX86 -g 
>  -c hid.c -o hid.o
>  hid.c: In function `HidD_Hello':
>  hid.c:374: warning: duplicate `const'
>  make: *** [hid.o] Error 1
>
>
>  const PCHAR const HelloString = "Hello\n";
>                ^
>                | is that right?
>
>
>  I'm back online!
>  James
>  _______________________________________________
>  Ros-dev mailing list
>  Ros-dev(a)reactos.com
>  http://reactos.com:8080/mailman/listinfo/ros-dev
>
>  
it should be right - it is a constant pointer to constant data. But i'm 
not 100% sure if it's just a c++ feature.

Best Regards
Thomas