BSTR <-> char* conversion(s) (implemented as C++ class) 2

alexregistry · May 13, 2000

Hi all, I tried to find the article where Don Box discusses many variations of BSTR <-> char* conversion. I desperately need it. Can any one send me that article from MSJ August 1995 Interfaces and the Registry/GetActiveObject Vs. MFC? Anybody has code on this topic? Thanks a lot.

gleason · May 18, 2000

I use a COM support class called _bstr_t which is defined in COMDEF.H. It wraps the BSTR type.  You can construct a _bstr_t object passing it a BSTR and use a built-in =operator function to extract the data as char*, and vice versa. Hope this helps! Pat Gleason <a href=mailto:gleason@megsinet.net>gleason@megsinet.net</a> <a href= > </a>

alexregistry · May 20, 2000

char* <-> BSTR wchar_t* <-> BSTR wchar_t* <-> char* Can I have all these conversions in one single class?

aljehin · Jun 9, 2000

#include <comdef.h> #ifndef _CONV_H #define _CONV_H class toBSTR { public:    // Foreign constructors    toBSTR (const char    *p8);    toBSTR (const wchar_t *p16);    // Native Constructor    toBSTR (const BSTR     bstr);    // Non-virtual destructor (this class is concrete)    ~toBSTR (void);    // Native conversion operator    operator const BSTR (void) const; private:    // Native BSTR string    BSTR   m_bstr;    // Is foreign?    BOOL   m_bIsForeign;    // Protect against assignment: just declare the prototypes of the copy    // constructor and assignment operator, and DO NOT implement them    toBSTR (const toBSTR&);    toBSTR& operator= (const toBSTR&); }; // Foreign constructors require allocation of a native // string and conversion inline toBSTR::toBSTR (const char *p8) : m_bstr (SysAllocStringLen (0, strlen (p8))), m_bIsForeign (TRUE)   // SysAllocStringLen appends a NULL characther {    // If the 1st arg. is NULL, mbstowcs() returns the required size    // of the destination string.    size_t size = mbstowcs (0, p8, strlen (p8)) + 1;    mbstowcs (m_bstr, p8, size); } inline toBSTR::toBSTR (const wchar_t *p16) : m_bstr (SysAllocString(p16)), m_bIsForeign (TRUE) { } // Native constructor is a pass-through. inline toBSTR::toBSTR (const BSTR bstr) : m_bstr (bstr), m_bIsForeign (FALSE) { } // Simply give out the native wideness string. inline toBSTR:

perator const BSTR (void) const {    return m_bstr; } // Destructor: Delete native string only if synthesized // in foreign constructor. inline toBSTR::~toBSTR (void) {   if (m_bIsForeign)   {     SysFreeString(m_bstr);   } } class toCStringW { public:    // Native constructor    toCStringW (const wchar_t *p16);    // Foreign constructors    toCStringW (const char    *p8);    toCStringW (const BSTR     bstr);    // Non-virtual destructor (this class is concrete)    ~toCStringW (void);    // Native conversion operator    operator const wchar_t * (void) const; private:    // Native wideness string: wchar_t*    wchar_t *m_sz;    // Is foreign?    BOOL     m_bIsForeign;    // Protect against assignment    toCStringW (const toCStringW&);    toCStringW& operator= (const toCStringW&); }; // Native constructor is a pass-through inline toCStringW::toCStringW (const wchar_t *p16) : m_sz ((wchar_t *)p16), m_bIsForeign (FALSE) { } // Foreign constructors require allocation of a native // string and conversion inline toCStringW::toCStringW (const char *p8) : m_bIsForeign (TRUE) {    // Calculate required buffer size (some characters may    // already occupy 16-bits under DBCS)    size_t size = mbstowcs (0, p8, strlen(p8)) + 1;    // Alloc native string and convert    if (m_sz = new wchar_t[size])    {       mbstowcs (m_sz, p8, size);    } } inline toCStringW::toCStringW (const BSTR  bstr) : m_bIsForeign (TRUE) {    // Calculate required buffer size    size_t size = wcstombs (0, bstr, wcslen (bstr)) + 1;    // Alloc native string and convert    if (m_sz = new wchar_t[size])    {       m_sz = bstr;    } } // Simply give out the native wideness string inline toCStringW:

perator const wchar_t * (void) const {    return m_sz; } // Delete w_char* string only if synthesized in foreign constructor inline toCStringW::~toCStringW (void) {   if (m_bIsForeign)   {     delete[] m_sz;   } } class toCString { public:    // Native constructor    toCString (const char *p8);    // Foreign constructors    toCString (const wchar_t *p16);    toCString (const BSTR     bstr);    // Non-virtual destructor    ~toCString (void);    // Native conversion operator    operator const char * (void) const; private:    // Native wideness string: char*    char *m_sz;    // Is foreign?    BOOL  m_bIsForeign;    // Protect against assignment    toCString (const toCString&);    toCString& operator= (const toCString&); }; // Native constructor is a pass-through inline toCString::toCString (const char *p8) : m_sz ((char*)p8), m_bIsForeign (FALSE) { } // Foreign constructor requires allocation of a native // string and conversion inline toCString::toCString (const wchar_t *p16) : m_bIsForeign(TRUE) {    // Calculate required buffer size (some characters may    // require more than one byte under DBCS)    size_t size = wcstombs (0, p16, wcslen (p16)) + 1;    // Alloc native string and convert    if (m_sz = new char[size])    {       wcstombs (m_sz, p16, size);    } } // Simply give out the native wideness string inline toCString:

perator const char * (void) const {    return m_sz; } // Delete native string only if synthesized in foreign constructor inline toCString::~toCString (void) {    if (m_bIsForeign)    {       delete[] m_sz;    } } #endif  // _CONV_H

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BSTR <-> char* conversion(s) (implemented as C++ class) 2

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BSTR <-> char* conversion(s) (implemented as C++ class) 2