Marshal.StringToHGlobalAnsi and multibyte strings

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Hesse - 19 Oct 2004 20:47 GMT

Does Marshal.StringToHGlobalAnsi convert System.String to multibyte strings
if necessary (if the System.String contains non-ANSI characters), or does it
only convert ansi strings?

If it converts UNICODE characters to appropriate multibyte characters, what
code page does it use for the conversion? Is it the operating system
(Windows) code page (i.e. on Japanese windows, will it use the Japanese code
page)?

Thanks!

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Jochen Kalmbach - 19 Oct 2004 21:00 GMT

=?Utf-8?B?SGVzc2U=?= wrote:

> Does Marshal.StringToHGlobalAnsi convert System.String to multibyte
> strings if necessary (if the System.String contains non-ANSI
> characters), or does it only convert ansi strings?

It converts to MBCS.

See: What is an ANSI string?
http://blog.kalmbachnet.de/?postid=19

> If it converts UNICODE characters to appropriate multibyte characters,
> what code page does it use for the conversion? Is it the operating
> system (Windows) code page (i.e. on Japanese windows, will it use the
> Japanese code page)?

I think they use "CP_ACP" (but I am not sure.. maybe I will dig into it...)

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Greetings
Jochen

My blog about Win32 and .NET
http://blog.kalmbachnet.de/

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Jochen Kalmbach - 20 Oct 2004 07:05 GMT

> I think they use "CP_ACP" (but I am not sure.. maybe I will dig into
> it...)

I looked at it:
It is internally calling "WideCharToMultiByte" with codepage = CP_ACP

The codepage is hardcoded in the source of
"mscorwks!ML_CSTR_C2N_SR::DoConversion"

If you need a different codepade you could use the following code:

<code>
System::String *mstr = S"Hello world!";
char *ustr;

unsigned char c __gc[] =
System::Text::Encoding::GetEncoding(1252)->GetBytes(mstr);
unsigned char __pin*cc = &c[0];
ustr = new char[c->get_Length()+1];
strcpy(ustr, (char*) cc);

// now do something with the converted string

delete [] ustr;
</code>

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Greetings
Jochen

My blog about Win32 and .NET
http://blog.kalmbachnet.de/

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Hesse - 20 Oct 2004 16:49 GMT

Thanks Jochen! That answered my questions!

> > I think they use "CP_ACP" (but I am not sure.. maybe I will dig into
> > it...)
[quoted text clipped - 21 lines]
> delete [] ustr;
> </code>

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Hesse - 20 Oct 2004 18:17 GMT

Hi,

Does Marshal.PtrToStringAnsi do the exact reverse of
Marshal.StringToHGlobalAnsi, that is, does it call MultiByteToWideChar with
the CP_ACP code page?

Thanks!

> > I think they use "CP_ACP" (but I am not sure.. maybe I will dig into
> > it...)
[quoted text clipped - 21 lines]
> delete [] ustr;
> </code>

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Jochen Kalmbach - 20 Oct 2004 18:22 GMT

Hi =?Utf-8?B?SGVzc2U=?=,

> Does Marshal.PtrToStringAnsi do the exact reverse of
> Marshal.StringToHGlobalAnsi, that is, does it call MultiByteToWideChar
> with the CP_ACP code page?

I have not verified, but according to the doc: yes.

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Greetings
Jochen

My blog about Win32 and .NET
http://blog.kalmbachnet.de/

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Marshal.StringToHGlobalAnsi and multibyte strings

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