convert CComBstr to char

[dskp]

how do i convert CComBstr to char;

char c;
CComBstr code;

c = *code;

is the above conversion correct or is there any other method ?

please help.its urgent....

[Codeplug]

If you know that the first character is a simple ASCII value (in the range of 0x00-0x1F), then you could simply use:

char c = static_cast<char>(*code.m_str);

gg

[Arjay]

See the CComBSTR::operator = in msdn.

CComBstr code(_T("Hello World!"));

// Get the string as ANSI or UNICODE
LPCSTR sz = code;

// Retrieve the ANSI or UNICODE character
TCHAR c = sz[0]; // 'H'

[Codeplug]

Doesn't compile.
"CComBSTR" - and it doesn't have an "operator LPCSTR".

#include <atlbase.h>
#include <iostream>
using namespace std;

int main()
{
    CComBSTR code(_T("Hello World!"));
    char c = static_cast<char>(*code.m_str);
    cout << c << endl;
    return 0;
}//main

gg

[Igor Vartanov]

No cast, as BSTR is WCHAR[] inside. Therefore, conversion is needed from WCHAR[] to CHAR[]:

#include <stdio.h>
#include <stdlib.h>
#include <atlbase.h>

int main()
{
	CComBSTR bstr(L"Hello World!");
	
	CHAR mbs[20] = {0};
	wcstombs(mbs, bstr, sizeof(mbs));
	printf("&#37;s\n", mbs);

	return 0;
}

[Arjay]

Doesn't compile.
"CComBSTR" - and it doesn't have an "operator LPCSTR".

#include <atlbase.h>
#include <iostream>
using namespace std;

int main()
{
    CComBSTR code(_T("Hello World!"));
    char c = static_cast<char>(*code.m_str);
    cout << c << endl;
    return 0;
}//main

gg

Looks like the msdn link I gave was incorrect.

No biggie - just use the string conversion macro.

CComBSTR code( _T("Hello World!") );

USES_CONVERSION;

LPTSTR sz = OLE2T( code );

TCHAR c = sz[0];

The above works in ANSI and UNICODE.

When working in Windows code, any code that uses 'char' makes me cringe ('cuz I now it's going to be a pain if I ever need to port the code to UNICODE).

[VladimirF]

If you know that the first character is a simple ASCII value (in the range of 0x00-0x1F), then you could simply use:

char c = static_cast<char>(*code.m_str);

gg

I don't have my crystal ball here with me (I am at work), but I am pretty sure OP doesn't just want one character from that BSTR.
The issue is that BSTR is a pointer to WCHAR, so a conversion (like W2A) is needed.

[Codeplug]

>> ** how do i convert CComBstr to char **
I don't have a crystal ball either - so I only answered the quested asked by the OP (under the condition that it's an ASCII value less than 0x1F).

They didn't ask how to convert to a TCHAR, TCHAR[], or CHAR[] - but now this thread contains solutions to all of those

>> Looks like the msdn link I gave was incorrect.
No, its correct.

gg

[Arjay]

>> Looks like the msdn link I gave was incorrect.
No, its correct.

While the link is correct, the content within the link is incorrect.

The link shows the following operator = overload...

CComBSTR& operator =(
   LPCSTR pSrc 
);

It doesn't exist and there is no such thing as LPCSTR.

[Codeplug]

It's there - and it works.

#include <atlbase.h>
#include <iostream>
using namespace std;

int main()
{
    CComBSTR code;
    code = "Hello World";
    char c = static_cast<char>(*code.m_str);
    cout << c << endl;
    return 0;
}//main

gg

[Arjay]

It's there - and it works.

If you are referring to my response, it isn't there.

Notice the difference between your code

*code.m_str

and mine

OLE2T( code );

My code uses the LPOLESTR = operator, yours accesses the underlying BSTR pointer.

You're getting lucky with your code.

[Codeplug]

While the link is correct, the content within the link is incorrect.

The link shows the following operator = overload...

CComBSTR& operator =(
   LPCSTR pSrc 
);

It doesn't exist and there is no such thing as LPCSTR.

I didn't really think you needed a C++ lesson...

First, LPCSTR is such a thing - it's a pointer to a const CHAR string.

Second, "operator=(LPCSTR)" is invoked when there is an LPCSTR on the right-hand-side of the object. Which is why my example included {code = "Hello World"}. It compiles without error. "It" obviously exists - as the documentation indicates.

>> LPCSTR sz = code;
Your code here does not compile because there is no "operator LPCSTR()" - which I mentioned in post #4. This is also refered to as a "cast operator". operator LPCSTR() would be invoked here, if it existed.

gg

[Arjay]

I didn't really think you needed a C++ lesson...

First, LPCSTR is such a thing - it's a pointer to a const CHAR string.

Second, "operator=(LPCSTR)" is invoked when there is an LPCSTR on the right-hand-side of the object. Which is why my example included {code = "Hello World"}. It compiles without error. "It" obviously exists - as the documentation indicates.

>> LPCSTR sz = code;
Your code here does not compile because there is no "operator LPCSTR()" - which I mentioned in post #4. This is also refered to as a "cast operator". operator LPCSTR() would be invoked here, if it existed.

gg

Thanks. Everyone once in a while things fall through the cracks. Still don't like the char though.

[dskp]

Thank's a lot for the replies.