Conversion from System::String^ to LPCTSTR

[=?Utf-8?B?Sm9hY2hpbQ==?=]

I have seen the following function to convert from a System::String^ to a
const wchar_t*. I would like to get a LPCTSTR and AFAIK LPCTSTR is equal to
const wchar_t*. Then it should all work right? But I only get the first
character. And when I try to do std::wstring l_s(convert(som estring)) I get
really strange characters into l_s string representation, but when I check
l_s individual characters they look ok.

const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

[Jochen Kalmbach [MVP]]

Hi Joachim!

I would like to get a LPCTSTR and AFAIK LPCTSTR is equal to
const wchar_t*.

No. LPCTSTR ist either const char* or const wchar_t* depending on
UNICODE macro.

My prefered way for cenversion is:

#include <windows.h>
#include <tchar.h>
using namespace System;
struct StringConvA
{
char *szAnsi;
StringConvA(Sys tem::String ^s)
:
szAnsi(static_c ast<char*>(Syst em::Runtime::In teropServices:: Marshal::String ToHGlobalAnsi(s ).ToPointer()))

{}
~StringConvA()
{

System::Runtime ::InteropServic es::Marshal::Fr eeHGlobal(IntPt r(szAnsi));
}
operator LPCSTR() const
{
return szAnsi;
}
};

struct StringConvW
{
wchar_t *szUnicode;
StringConvW(Sys tem::String^ s)
:
szUnicode(stati c_cast<wchar_t* >(System::Runti me::InteropServ ices::Marshal:: StringToHGlobal Uni(s).ToPointe r()))

{}
~StringConvW()
{

System::Runtime ::InteropServic es::Marshal::Fr eeHGlobal(IntPt r(szUnicode));
}
operator LPCWSTR() const
{
return szUnicode;
}
};

#ifdef _UNICODE
#define StringConvT StringConvW
#else
#define StringConvT StringConvA
#endif

And then use it with:
#include <string>
int _tmain()
{
String ^s = "abc";
std::string ansi = StringConvA(s);
std::wstring unicode = StringConvW(s);
}

or

#include <stdio.h>
int _tmain()
{
String ^s = "abc";
printf("%s", (LPCSTR) StringConvA(s)) ;
wprintf(L"%s", (LPCWSTR) StringConvW(s)) ;
_tprintf(_T("%s "), (LPCTSTR) StringConvT(s)) ;
return 0;
}
Greetings
Jochen

[=?Utf-8?B?Sm9hY2hpbQ==?=]

Thanks Jochen,

I still only get the first character...

Regards,
Joachim

"Jochen Kalmbach [MVP]" wrote:

Hi Joachim!

I would like to get a LPCTSTR and AFAIK LPCTSTR is equal to
const wchar_t*.

No. LPCTSTR ist either const char* or const wchar_t* depending on
UNICODE macro.

My prefered way for cenversion is:

#include <windows.h>
#include <tchar.h>
using namespace System;
struct StringConvA
{
char *szAnsi;
StringConvA(Sys tem::String ^s)
:
szAnsi(static_c ast<char*>(Syst em::Runtime::In teropServices:: Marshal::String ToHGlobalAnsi(s ).ToPointer()))

{}
~StringConvA()
{

System::Runtime ::InteropServic es::Marshal::Fr eeHGlobal(IntPt r(szAnsi));
}
operator LPCSTR() const
{
return szAnsi;
}
};

struct StringConvW
{
wchar_t *szUnicode;
StringConvW(Sys tem::String^ s)
:
szUnicode(stati c_cast<wchar_t* >(System::Runti me::InteropServ ices::Marshal:: StringToHGlobal Uni(s).ToPointe r()))

{}
~StringConvW()
{

System::Runtime ::InteropServic es::Marshal::Fr eeHGlobal(IntPt r(szUnicode));
}
operator LPCWSTR() const
{
return szUnicode;
}
};

#ifdef _UNICODE
#define StringConvT StringConvW
#else
#define StringConvT StringConvA
#endif

And then use it with:
#include <string>
int _tmain()
{
String ^s = "abc";
std::string ansi = StringConvA(s);
std::wstring unicode = StringConvW(s);
}

or

#include <stdio.h>
int _tmain()
{
String ^s = "abc";
printf("%s", (LPCSTR) StringConvA(s)) ;
wprintf(L"%s", (LPCWSTR) StringConvW(s)) ;
_tprintf(_T("%s "), (LPCTSTR) StringConvT(s)) ;
return 0;
}
Greetings
Jochen

[Ben Voigt]

const wchar_t* convert(

System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

Complete misuse of pin_ptr here. You must never use a pin_ptr as a return
value.

OTOH, this will work, because the wstring constructor is called while the
string is still pinned:

std::wstring convert(System: :String^ const s)
{
return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
}

[=?Utf-8?B?Sm9hY2hpbQ==?=]

Thank you Ben,

However, that still doesn't solve my problem (and by the way I get
compilation error with it:

error C3834: illegal explicit cast to a pinning pointer; use a pinned local
variable instead f:\Development\ Source\Test\MCP P\MCPP\MCPPImpl .cpp 54)

Regards,
Joachim
"Ben Voigt" wrote:

const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

Complete misuse of pin_ptr here. You must never use a pin_ptr as a return
value.

OTOH, this will work, because the wstring constructor is called while the
string is still pinned:

std::wstring convert(System: :String^ const s)
{
return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
}

[Ben Voigt]

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:12******** *************** ***********@mic rosoft.com...

Thank you Ben,

However, that still doesn't solve my problem (and by the way I get
compilation error with it:

error C3834: illegal explicit cast to a pinning pointer; use a pinned
local
variable instead f:\Development\ Source\Test\MCP P\MCPP\MCPPImpl .cpp 54)

ok, yeah, pin_ptr needs an explicit local, so split the one-liner:

std::wstring convert(System: :String^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
return std::wstring(wc h);
}

Regards,
Joachim
"Ben Voigt" wrote:

const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

Complete misuse of pin_ptr here. You must never use a pin_ptr as a
return
value.

OTOH, this will work, because the wstring constructor is called while the
string is still pinned:

std::wstring convert(System: :String^ const s)
{
return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
}

[=?Utf-8?B?Sm9hY2hpbQ==?=]

Ben,

Yes that did compile, but it didn't solve the problem

Regards,
Joachim

"Ben Voigt" wrote:

>
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:12******** *************** ***********@mic rosoft.com...

Thank you Ben,

However, that still doesn't solve my problem (and by the way I get
compilation error with it:

error C3834: illegal explicit cast to a pinning pointer; use a pinned
local
variable instead f:\Development\ Source\Test\MCP P\MCPP\MCPPImpl .cpp 54)

ok, yeah, pin_ptr needs an explicit local, so split the one-liner:

std::wstring convert(System: :String^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
return std::wstring(wc h);
}

Regards,
Joachim
"Ben Voigt" wrote:

const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

Complete misuse of pin_ptr here. You must never use a pin_ptr as a
return
value.

OTOH, this will work, because the wstring constructor is called while the
string is still pinned:

std::wstring convert(System: :String^ const s)
{
return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
}

[Ben Voigt]

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:19******** *************** ***********@mic rosoft.com...

Ben,

Yes that did compile, but it didn't solve the problem

Regards,
Joachim

How about:

std::basic_stri ng<TCHARconvert (System::String ^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
#if _UNICODE
return std::wstring(wc h);
#else
int needed = wcstombs(nullpt r, wch, 0) + 1;
char* pch = alloca(needed);
wcstombs(pch, wch, needed);
// optional, unpin early with wch = nullptr;
return std::string(pch );
#endif
}

>
"Ben Voigt" wrote:

>>
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:12******* *************** ************@mi crosoft.com...

Thank you Ben,

However, that still doesn't solve my problem (and by the way I get
compilation error with it:

error C3834: illegal explicit cast to a pinning pointer; use a pinned
local
variable instead f:\Development\ Source\Test\MCP P\MCPP\MCPPImpl .cpp 54)

ok, yeah, pin_ptr needs an explicit local, so split the one-liner:

std::wstring convert(System: :String^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
return std::wstring(wc h);
}

Regards,
Joachim
"Ben Voigt" wrote:

const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

Complete misuse of pin_ptr here. You must never use a pin_ptr as a
return
value.

OTOH, this will work, because the wstring constructor is called while
the
string is still pinned:

std::wstring convert(System: :String^ const s)
{
return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
}

[=?Utf-8?B?Sm9hY2hpbQ==?=]

No, it is unicode.

"Ben Voigt" wrote:

>
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:19******** *************** ***********@mic rosoft.com...

Ben,

Yes that did compile, but it didn't solve the problem

Regards,
Joachim

How about:

std::basic_stri ng<TCHARconvert (System::String ^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
#if _UNICODE
return std::wstring(wc h);
#else
int needed = wcstombs(nullpt r, wch, 0) + 1;
char* pch = alloca(needed);
wcstombs(pch, wch, needed);
// optional, unpin early with wch = nullptr;
return std::string(pch );
#endif
}

"Ben Voigt" wrote:

>
"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:12******** *************** ***********@mic rosoft.com...
Thank you Ben,

However, that still doesn't solve my problem (and by the way I get
compilation error with it:

error C3834: illegal explicit cast to a pinning pointer; use a pinned
local
variable instead f:\Development\ Source\Test\MCP P\MCPP\MCPPImpl .cpp 54)


ok, yeah, pin_ptr needs an explicit local, so split the one-liner:

std::wstring convert(System: :String^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
return std::wstring(wc h);
}

Regards,
Joachim
"Ben Voigt" wrote:

const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);

return wch;
}

Complete misuse of pin_ptr here. You must never use a pin_ptr as a
return
value.

OTOH, this will work, because the wstring constructor is called while
the
string is still pinned:

std::wstring convert(System: :String^ const s)
{
return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
}

[=?Utf-8?B?Sm9hY2hpbQ==?=]

The (3rd party) function which I am passing the LPCTSTR on to takes and
LPCTSTR as argument and is working in a native C++/ATL/COM environment. In
that environment it is passed as a TCHAR*. But in this Managed C++
environment, even if I directly before the call to the function specifies
TCHAR* l_s(_T("test.mp g")) it only comes out as the filename "t".

"Joachim" wrote:

No, it is unicode.

"Ben Voigt" wrote:

"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
news:19******** *************** ***********@mic rosoft.com...

Ben,
>
Yes that did compile, but it didn't solve the problem
>
Regards,
Joachim

How about:

std::basic_stri ng<TCHARconvert (System::String ^ const s)
{
pin_ptr<const wchar_twch = PtrToStringChar s(s);
#if _UNICODE
return std::wstring(wc h);
#else
int needed = wcstombs(nullpt r, wch, 0) + 1;
char* pch = alloca(needed);
wcstombs(pch, wch, needed);
// optional, unpin early with wch = nullptr;
return std::string(pch );
#endif
}

>
>
>
"Ben Voigt" wrote:
>
>>
>"Joachim" <Jo*****@discus sions.microsoft .comwrote in message
>news:12******* *************** ************@mi crosoft.com...
Thank you Ben,
>
However, that still doesn't solve my problem (and by the way I get
compilation error with it:
>
error C3834: illegal explicit cast to a pinning pointer; use a pinned
local
variable instead f:\Development\ Source\Test\MCP P\MCPP\MCPPImpl .cpp 54)
>
>>
>ok, yeah, pin_ptr needs an explicit local, so split the one-liner:
>>
>std::wstring convert(System: :String^ const s)
>{
> pin_ptr<const wchar_twch = PtrToStringChar s(s);
> return std::wstring(wc h);
>}
>>
Regards,
Joachim
>
>
"Ben Voigt" wrote:
>
const wchar_t* convert(
System::String^ s)
{
// Pin memory so GC can't move it while native function is called
pin_ptr<const wchar_twch = PtrToStringChar s(s);
>
return wch;
}
>>
>Complete misuse of pin_ptr here. You must never use a pin_ptr as a
>return
>value.
>>
>OTOH, this will work, because the wstring constructor is called while
>the
>string is still pinned:
>>
>std::wstring convert(System: :String^ const s)
>{
> return std::wstring(pi n_ptr<const wchar_t>(PtrToS tringChars(s))) ;
>}
>>
>>
>>
>>
>>
>>