C / C++ / MFC Discussion Boards

Re: C++ Detect WLAN

David Crow20-Aug-07 5:37

David Crow

20-Aug-07 5:37

HStrix wrote:
...and found that it can only decide between LAN and WAN

And yet those were your exact requirements. Roll eyes | :rolleyes:

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: C++ Detect WLAN

HStrix20-Aug-07 5:45

HStrix

20-Aug-07 5:45

Sorry, perhaps there is some misunderstanding ..
I want to decide between WLAN und LAN
and not between WAN and LAN ..

Re: C++ Detect WLAN

David Crow20-Aug-07 5:56

David Crow

20-Aug-07 5:56

HStrix wrote:
Sorry, perhaps there is some misunderstanding ..

Yes, I failed to realize W was for Wireless not Wide. Blush | :O

You can use GetAdaptersInfo() for this. With the adapter name from that, call CreateFile() to get a handle, and call DeviceIOControl(..., IOCTL_NDISUIO_QUERY_OID_VALUE, ...). I've not fully tried this, however.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: C++ Detect WLAN

HStrix20-Aug-07 6:07

HStrix

20-Aug-07 6:07

Thank you,
this looks good.
I'll give it a try.
Maybe it takes some time ..

L macro

George_George20-Aug-07 5:11

George_George

20-Aug-07 5:11

Hello everyone,

I am using Visual Studio 2003 and Windows Console project, I find when using L macro to convert character to wide character, the compiler will report an error that L macro is not defined.

I find it is not defined in either <windows.h> or <tchar.h> -- when adding the two header files, the compile error is the same.

Could anyone explain how to use L macro in Visual Studio 2003 and Windows Console project? Which header file is needed?

thanks in advance,
George

Re: L macro

David Crow20-Aug-07 5:25

David Crow

20-Aug-07 5:25

George_George wrote:
...I find when using L macro to convert...

Technically speaking, I do not believe L is a macro.

George_George wrote:
the compiler will report an error that L macro is not defined.

What does the offending statement look like?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: L macro

George_George20-Aug-07 17:07

George_George

20-Aug-07 17:07

Thanks David,

The statement is simple, something like, L"hello". Why do you think it is not a macro? Who to use L in Visual Studio 2003 Windows Console project?

regards,
George

Re: L macro

David Crow20-Aug-07 17:14

David Crow

20-Aug-07 17:14

If it were a macro (i.e. preprocessor directive), it would resolve to something.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: L macro

George_George20-Aug-07 17:45

George_George

20-Aug-07 17:45

Hi David,

If it is not a macro, what is it?

regards,
George

Re: L macro

David Crow20-Aug-07 17:51

David Crow

20-Aug-07 17:51

George_George wrote:
If it is not a macro, what is it?

It's simply a prefix to denote wide-string literals.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: L macro

George_George20-Aug-07 19:19

George_George

20-Aug-07 19:19

Thanks David,

I can understand your point. I mean there should be a technical terminology to call it -- besides the term "prefix". So, if it is not macro, what is it? There is not a technical terminology called "prefix". Smile | :)

regards,
George

Re: L macro

toxcct20-Aug-07 22:11

toxcct

20-Aug-07 22:11

George_George wrote:
If it is not a macro, what is it?

it's an extended keyword of the language

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Re: L macro

George_George20-Aug-07 22:27

George_George

20-Aug-07 22:27

Thanks toxcct,

I want to confirm that keyword L could only be used in C++ and not in C. Right?

regards,
George

Re: L macro

toxcct20-Aug-07 22:37

toxcct

20-Aug-07 22:37

George_George wrote:
want to confirm that keyword L could only be used in C++ and not in C

then why didn't you asked clearly ?
and why do you bother that much ? why is it that important ?
can't you just search the WEB for that easy info ?

BTW, what is it that you vote everybody to '4' ???

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Re: L macro

George_George21-Aug-07 1:05

George_George

21-Aug-07 1:05

Thanks toxcct,

I can not find answer from MSDN so I come here. We could only use L in C++? Can not use in C?

regards,
George

Re: L macro

Iain Clarke, Warrior Programmer20-Aug-07 5:39

Iain Clarke, Warrior Programmer

20-Aug-07 5:39

As has been said, L is not a macro...

char narrow [] = "abc";
TCHAR either [] = _T("abc"); // uses a macro
wchar_t wide [0] = L"abc";

short a = 1L; // will give a warning at least

The last example shows that L is also useful for non-chars, etc.

Iain.

Re: L macro

George_George20-Aug-07 17:13

George_George

20-Aug-07 17:13

Thanks Iain,

You code can not compile in my VS 2003 environment,

This statement

wchar_t* wide [] = L"abc";

error C2075: 'wide' : array initialization needs curly braces

When I change to L("hello"), there is an error from compiler that L is undefined.

regards,
George

Re: L macro

Maxwell Chen20-Aug-07 19:39

Maxwell Chen

20-Aug-07 19:39

George_George wrote:
can not compile in my VS 2003 environment,
This statement
wchar_t* wide [] = L"abc";
error C2075: 'wide' : array initialization needs curly braces
When I change to L("hello"), there is an error from compiler that L is undefined.

The below works fine with Visual Studio 2005.

char narrow [] = "abc";
wchar_t wide [] = L"abc";
short a = 1L; // will give a warning at least

Maxwell Chen

Re: L macro

George_George20-Aug-07 20:17

George_George

20-Aug-07 20:17

Thanks Maxwell,

I have verified that it is ok.

regards,
George

LPCSTR and LPCWSTR

George_George20-Aug-07 4:56

George_George

20-Aug-07 4:56

Hello everyone,

I think when UNICODE or _UNICODE is defined, when using _T, it could convert characters to wide character.

And I also think LPCSTR should be defined to pointer to wide character when UNICODE or _UNICODE is defined, and LPCSTR should be defined to pointer to multibyte character when UNICODE and _UNICODE are not defined.

But it seems I am wrong for all points. Could anyone explain to me why I get such warnings in Visual Studio 2003?

<br />
#include "windows.h"<br />
#include "TCHAR.h"<br />
<br />
#define UNICODE<br />
#define _UNICODE<br />
<br />
int main (int argc, char** argv)<br />
{<br />
        WCHAR* p = _T("hello");<br />
        LPCSTR p1 = p;<br />
        LPCWSTR p2 = p;<br />
}<br />

warning messages,

warning C4133: 'initializing' : incompatible types - from 'char [6]' to 'WCHAR *'
warning C4133: 'initializing' : incompatible types - from 'WCHAR *' to 'LPCSTR'

thanks in advance,
George

Re: LPCSTR and LPCWSTR

David Crow20-Aug-07 5:31

David Crow

20-Aug-07 5:31

The warnings are self-explanatory. With LPCSTR p1 = p, you are trying to assign a WCHAR* (an unsigned short*) to a LPCSTR (a char*), which is incompatible.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: LPCSTR and LPCWSTR

George_George20-Aug-07 17:30

George_George

20-Aug-07 17:30

Thanks David,

I think we should use LPCTSTR, which is defined to LPCSTR when UNICODE and _UNICODE are not defined, and defined to LPCWSTR when UNICODE or _UNICODE is defined. Right?

regards,
George

Re: LPCSTR and LPCWSTR

David Crow20-Aug-07 17:45

David Crow

20-Aug-07 17:45

George_George wrote:
Right?

Yes.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: LPCSTR and LPCWSTR

George_George20-Aug-07 17:47

George_George

20-Aug-07 17:47

Hi David,

A further question,

why the statement has warning message when UNICODE is defined (you can find it from my sample in question)?

WCHAR* p = _T("hello");

warning C4133: 'initializing' : incompatible types - from 'char [6]' to 'WCHAR *'

regards,
George

Re: LPCSTR and LPCWSTR

David Crow21-Aug-07 3:13

David Crow

21-Aug-07 3:13

I get this error when Unicode is not defined. If Unicode is defined, it compiles fine.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

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