WriteFile issue

[=?Utf-8?B?R2Vvcmdl?=]

Hello everyone,
The 3rd parameter of WriteFile is number of bytes to write,

http://msdn2.microsoft.com/en-us/library/aa365747.aspx

I am wondering if I want to write multi-byte character string or wide
character string on Windows, how could I get the number of bytes?
thanks in advance,
George

[David Wilkinson]

George wrote:

Hello everyone,
The 3rd parameter of WriteFile is number of bytes to write,

http://msdn2.microsoft.com/en-us/library/aa365747.aspx

I am wondering if I want to write multi-byte character string or wide
character string on Windows, how could I get the number of bytes?

George:

MBCS is a non-issue; you are just writing the data.

LPCTSTR str = _T("Test String");
size_t nBytes = _tcslen(str)*sizeof(TCHAR);

--
David Wilkinson
Visual C++ MVP

[=?Utf-8?B?R2Vvcmdl?=]

Thanks David,
You mean MBCS is always ends with 0 and I can use strlen safely?

And for the sizeof (TCHAR), could I assume it is always 2 bytes? Are there
any exceptions?
regards,
George

"David Wilkinson" wrote:

George wrote:

Hello everyone,
The 3rd parameter of WriteFile is number of bytes to write,

http://msdn2.microsoft.com/en-us/library/aa365747.aspx

I am wondering if I want to write multi-byte character string or wide
character string on Windows, how could I get the number of bytes?

George:

MBCS is a non-issue; you are just writing the data.

LPCTSTR str = _T("Test String");
size_t nBytes = _tcslen(str)*sizeof(TCHAR);

--
David Wilkinson
Visual C++ MVP

[Ben Voigt [C++ MVP]]

"George" <Ge****@discussions.microsoft.comwrote in message
news:66**********************************@microsof t.com...

Hello everyone,
The 3rd parameter of WriteFile is number of bytes to write,

http://msdn2.microsoft.com/en-us/library/aa365747.aspx

I am wondering if I want to write multi-byte character string or wide
character string on Windows, how could I get the number of bytes?

Just use StringCbLength, which always returns the number of bytes regardless
of whether you are compiled for SBCS, MBCS, or UNICODE.

>

thanks in advance,
George

[David Wilkinson]

George wrote:

Thanks David,

You mean MBCS is always ends with 0 and I can use strlen safely?

And for the sizeof (TCHAR), could I assume it is always 2 bytes? Are there
any exceptions?

George:

The whole point of TCHAR is that it is one byte in ANSI build and 2
bytes in Unicode build. This is what enables you to use a single code
base for either kind of build.

If you always use Unicode build, then sizeof(TCHAR) is always 2 (and you
can just use wchar_t and L"" strings). But for me, old habits die hard,
and I always use TCHAR and _T("") strings.

--
David Wilkinson
Visual C++ MVP

[=?Utf-8?B?R2Vvcmdl?=]

Thanks David, your answer is clear.
regards,
George

"David Wilkinson" wrote:

George wrote:

Thanks David,

You mean MBCS is always ends with 0 and I can use strlen safely?

And for the sizeof (TCHAR), could I assume it is always 2 bytes? Are there
any exceptions?

George:

The whole point of TCHAR is that it is one byte in ANSI build and 2
bytes in Unicode build. This is what enables you to use a single code
base for either kind of build.

If you always use Unicode build, then sizeof(TCHAR) is always 2 (and you
can just use wchar_t and L"" strings). But for me, old habits die hard,
and I always use TCHAR and _T("") strings.

--
David Wilkinson
Visual C++ MVP

[=?Utf-8?B?R2Vvcmdl?=]

Thanks Ben, the method is very helpful.
regards,
George

"Ben Voigt [C++ MVP]" wrote:

>
"George" <Ge****@discussions.microsoft.comwrote in message
news:66**********************************@microsof t.com...

Hello everyone,
The 3rd parameter of WriteFile is number of bytes to write,

http://msdn2.microsoft.com/en-us/library/aa365747.aspx

I am wondering if I want to write multi-byte character string or wide
character string on Windows, how could I get the number of bytes?

Just use StringCbLength, which always returns the number of bytes regardless
of whether you are compiled for SBCS, MBCS, or UNICODE.

thanks in advance,
George