subject_26635.htm

一些关于vc的问答

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序号：26635 发表者：janelinkey 发表日期：2003-01-03 11:47:59
<br>主题：ATL编写COM时如何传递带不规则字符，乱码，或空字符的字符串
<br>内容：用BSTR，转换宏会把空字符后的字符去掉。有什么办法？我的组件必须和VB通讯。
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<font color=red>答案被接受</font><br>回复者：_cpper 回复日期：2003-01-03 11:54:22
<br>内容：<BR>HRESULT __fastcall AnsiToUnicode(LPCSTR pszA, LPOLESTR* ppszW)<BR>{<BR>&nbsp;&nbsp; ULONG cCharacters;<BR>&nbsp;&nbsp; DWORD dwError;<BR><BR>&nbsp;&nbsp; // If input is null then just return the same.<BR>&nbsp;&nbsp; if (NULL == pszA)<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*ppszW = NULL;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return NOERROR;<BR>&nbsp;&nbsp; }<BR><BR>&nbsp;&nbsp; // Determine number of wide characters to be allocated for the<BR>&nbsp;&nbsp; // Unicode string.<BR>&nbsp;&nbsp; cCharacters =&nbsp;&nbsp;strlen(pszA)+1;<BR><BR>&nbsp;&nbsp; // Use of the OLE allocator is required if the resultant Unicode<BR>&nbsp;&nbsp; // string will be passed to another COM component and if that<BR>&nbsp;&nbsp; // component will free it. Otherwise you can use your own allocator.<BR>&nbsp;&nbsp; *ppszW = (LPOLESTR) CoTaskMemAlloc(cCharacters*2);<BR>&nbsp;&nbsp; if (NULL == *ppszW)<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return E_OUTOFMEMORY;<BR><BR>&nbsp;&nbsp; // Covert to Unicode.<BR>&nbsp;&nbsp; if (0 == MultiByteToWideChar(CP_ACP, 0, pszA, cCharacters,<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*ppszW, cCharacters))<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dwError = GetLastError();<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;CoTaskMemFree(*ppszW);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*ppszW = NULL;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return HRESULT_FROM_WIN32(dwError);<BR>&nbsp;&nbsp; }<BR><BR>&nbsp;&nbsp; return NOERROR;<BR>}<BR><BR><BR>/*<BR> * UnicodeToAnsi converts the Unicode string pszW to an ANSI string<BR> * and returns the ANSI string through ppszA. Space for the<BR> * the converted string is allocated by UnicodeToAnsi.<BR> */<BR>HRESULT __fastcall UnicodeToAnsi(LPCOLESTR pszW, LPSTR* ppszA)<BR>{<BR>&nbsp;&nbsp; ULONG cbAnsi, cCharacters;<BR>&nbsp;&nbsp; DWORD dwError;<BR><BR>&nbsp;&nbsp; // If input is null then just return the same.<BR>&nbsp;&nbsp; if (pszW == NULL)<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *ppszA = NULL;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return NOERROR;<BR>&nbsp;&nbsp; }<BR><BR>&nbsp;&nbsp; cCharacters = wcslen(pszW)+1;<BR>&nbsp;&nbsp; // Determine number of bytes to be allocated for ANSI string. An<BR>&nbsp;&nbsp; // ANSI string can have at most 2 bytes per character (for Double<BR>&nbsp;&nbsp; // Byte Character Strings.)<BR>&nbsp;&nbsp; cbAnsi = cCharacters*2;<BR><BR>&nbsp;&nbsp; // Use of the OLE allocator is not required because the resultant<BR>&nbsp;&nbsp; // ANSI string will never be passed to another COM component. You<BR>&nbsp;&nbsp; // can use your own allocator.<BR>&nbsp;&nbsp; *ppszA = (LPSTR) CoTaskMemAlloc(cbAnsi);<BR>&nbsp;&nbsp; if (NULL == *ppszA)<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return E_OUTOFMEMORY;<BR><BR>&nbsp;&nbsp; // Convert to ANSI.<BR>&nbsp;&nbsp; if (0 == WideCharToMultiByte(CP_ACP, 0, pszW, cCharacters, *ppszA,<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;cbAnsi, NULL, NULL))<BR>&nbsp;&nbsp; {<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dwError = GetLastError();<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;CoTaskMemFree(*ppszA);<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*ppszA = NULL;<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return HRESULT_FROM_WIN32(dwError);<BR>&nbsp;&nbsp; }<BR><BR>&nbsp;&nbsp; return NOERROR;<BR>}<BR> 
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