Help on CString to char*
in [MFC]
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From: jt on 17 Mar 2005 17:43 Being a newbie to MFC, I am having problems on copying CString to a char* Below is my attempt but I getting this error below: ===================================================== Debug Assertion Failed! Program: C:\geac\GEACstatusptt.exe File: dbgheap.c Line: 1044 Expression: _CrtIsValidHeapPointer(pUserData) Below is my code the way that I am doing now, look at switch 4 and this is where I call a DLL library "McaAddPageMember" ====================================================== char cPAGER_CODE[16]; CPsnstatuspttApp::m_LogTrace.WriteLine("CPsnstatuspttView::Call_Page_Member( )"); CTokenizer tok( cmdstr,","); CString cs; id=0; while(tok.Next(cs)) { switch (id){ case 0: iPAGER_FORMAT = (WORD) _ttoi(cs); //Feature, paging format break; case 1: GEAC_PAGE_ID = cs; break; case 2: iRID = (WORD) _ttoi(cs); // rid break; case 3: iFREQ = (WORD)_ttoi(cs); //frequency break; case 4: wsprintf(cPAGER_CODE,"%s",cs.GetBuffer(cs.GetLength())); // pager code bNumDigits=cs.GetLength(); break; } id++; } pEntry = NULL; pos = g_RCtable.GetHeadPosition(); while (pos) { _rid *pCurrent = g_RCtable.GetNext(pos); if (pCurrent->RC_id == iRID){ if (iFREQ==0) iFREQ=NULL_FREQ; CPsnstatuspttApp::m_LogTrace.WriteLine("McaAddPageMember PAGER CODE:%s",cPAGER_CODE); if(McaAddPageMember(pCurrent->LC_id, iFREQ, iPAGER_FORMAT, bNumDigits, cPAGER_CODE ) ) { CPsnstatuspttApp::m_LogTrace.WriteLine(" SUCCESSFUL API Call McaAddPageMember"); if ( McaBeginPaging () ) { CPsnstatuspttApp::m_LogTrace.WriteLine("SUCCESSFUL API Call McaBeginPaging"); sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); } else { CPsnstatuspttApp::m_LogTrace.WriteLine(" FAILED API Call McaBeginPaging"); sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); } } else { RetMsg="FAILED API Call McaAddPageMember()"; CPsnstatuspttApp::m_LogTrace.WriteLine(RetMsg); sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); } break; } pEntry = pCurrent; }
From: Uranium-235 on 17 Mar 2005 18:05 Sorry for not sifting through all your code. Copying a CString to a char can be as simple as the following. strcpy(szDestination, (char *) (LPCSTR) strSourceString); I hope this helps, "jt" wrote: > Being a newbie to MFC, I am having problems on copying CString to a char* > > Below is my attempt but I getting this error below: > ===================================================== > Debug Assertion Failed! > > Program: C:\geac\GEACstatusptt.exe > File: dbgheap.c > Line: 1044 > > Expression: _CrtIsValidHeapPointer(pUserData) > > Below is my code the way that I am doing now, look at switch 4 and > this is where I call a DLL library "McaAddPageMember" > ====================================================== > char cPAGER_CODE[16]; > > CPsnstatuspttApp::m_LogTrace.WriteLine("CPsnstatuspttView::Call_Page_Member( > )"); > > CTokenizer tok( cmdstr,","); > CString cs; > > id=0; > while(tok.Next(cs)) > { > switch (id){ > > case 0: iPAGER_FORMAT = (WORD) _ttoi(cs); //Feature, paging format > break; > case 1: GEAC_PAGE_ID = cs; > break; > case 2: iRID = (WORD) _ttoi(cs); // rid > break; > case 3: iFREQ = (WORD)_ttoi(cs); //frequency > break; > case 4: wsprintf(cPAGER_CODE,"%s",cs.GetBuffer(cs.GetLength())); // pager > code > bNumDigits=cs.GetLength(); > break; > } > id++; > } > > pEntry = NULL; > > pos = g_RCtable.GetHeadPosition(); > while (pos) > { > _rid *pCurrent = g_RCtable.GetNext(pos); > if (pCurrent->RC_id == iRID){ > > if (iFREQ==0) > iFREQ=NULL_FREQ; > > CPsnstatuspttApp::m_LogTrace.WriteLine("McaAddPageMember PAGER > CODE:%s",cPAGER_CODE); > > if(McaAddPageMember(pCurrent->LC_id, iFREQ, iPAGER_FORMAT, bNumDigits, > cPAGER_CODE ) ) > { > CPsnstatuspttApp::m_LogTrace.WriteLine(" SUCCESSFUL API Call > McaAddPageMember"); > > if ( McaBeginPaging () ) > { > CPsnstatuspttApp::m_LogTrace.WriteLine("SUCCESSFUL API Call > McaBeginPaging"); > sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); > } > else > { > CPsnstatuspttApp::m_LogTrace.WriteLine(" FAILED API Call > McaBeginPaging"); > sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); > } > > } > else > { > RetMsg="FAILED API Call McaAddPageMember()"; > CPsnstatuspttApp::m_LogTrace.WriteLine(RetMsg); > sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); > } > break; > } > pEntry = pCurrent; > } > > >
From: Tom Serface on 17 Mar 2005 18:29 Try subtracting 1 from the length (remembering it is 0 based as an index). You can also just cast the string (actually it does this on it's own most of the time) so long as it is not going to be modified (LPCTSTR). Tom "jt" <jtsoft(a)hotmail.com> wrote in message news:cKn_d.195801$JF2.189408(a)tornado.tampabay.rr.com... > Being a newbie to MFC, I am having problems on copying CString to a char* > > Below is my attempt but I getting this error below: > ===================================================== > Debug Assertion Failed! > > Program: C:\geac\GEACstatusptt.exe > File: dbgheap.c > Line: 1044 > > Expression: _CrtIsValidHeapPointer(pUserData) > > Below is my code the way that I am doing now, look at switch 4 and > this is where I call a DLL library "McaAddPageMember" > ====================================================== > char cPAGER_CODE[16]; > > CPsnstatuspttApp::m_LogTrace.WriteLine("CPsnstatuspttView::Call_Page_Member( > )"); > > CTokenizer tok( cmdstr,","); > CString cs; > > id=0; > while(tok.Next(cs)) > { > switch (id){ > > case 0: iPAGER_FORMAT = (WORD) _ttoi(cs); //Feature, paging format > break; > case 1: GEAC_PAGE_ID = cs; > break; > case 2: iRID = (WORD) _ttoi(cs); // rid > break; > case 3: iFREQ = (WORD)_ttoi(cs); //frequency > break; > case 4: wsprintf(cPAGER_CODE,"%s",cs.GetBuffer(cs.GetLength())); // pager > code > bNumDigits=cs.GetLength(); > break; > } > id++; > } > > pEntry = NULL; > > pos = g_RCtable.GetHeadPosition(); > while (pos) > { > _rid *pCurrent = g_RCtable.GetNext(pos); > if (pCurrent->RC_id == iRID){ > > if (iFREQ==0) > iFREQ=NULL_FREQ; > > CPsnstatuspttApp::m_LogTrace.WriteLine("McaAddPageMember PAGER > CODE:%s",cPAGER_CODE); > > if(McaAddPageMember(pCurrent->LC_id, iFREQ, iPAGER_FORMAT, bNumDigits, > cPAGER_CODE ) ) > { > CPsnstatuspttApp::m_LogTrace.WriteLine(" SUCCESSFUL API Call > McaAddPageMember"); > > if ( McaBeginPaging () ) > { > CPsnstatuspttApp::m_LogTrace.WriteLine("SUCCESSFUL API Call > McaBeginPaging"); > sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); > } > else > { > CPsnstatuspttApp::m_LogTrace.WriteLine(" FAILED API Call > McaBeginPaging"); > sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); > } > > } > else > { > RetMsg="FAILED API Call McaAddPageMember()"; > CPsnstatuspttApp::m_LogTrace.WriteLine(RetMsg); > sock.Send(msg.GetBuffer(msg.GetLength()), msg.GetLength()); > } > break; > } > pEntry = pCurrent; > } > >
From: Craig S. on 17 Mar 2005 22:51 A call to CString::GetBuffer() has to be followed by CString::ReleaseBuffer() before you do anything else with the CString object.
From: Tom Serface on 18 Mar 2005 14:19
Hi Craig, I think you only need to do this if you actually modify the string and need to resync it. So far as I know you don't have to do this if you pass the string as a const. That's why CString can do the automatic cast to LPCTSTR. However, that said, I don't think it hurts either so long as you don't change the length of the string... Tom "Craig S." <xxxx(a)ms.com> wrote in message news:u65B%2322KFHA.1280(a)TK2MSFTNGP09.phx.gbl... >A call to CString::GetBuffer() has to be followed by >CString::ReleaseBuffer() before you do anything else with the CString >object. > |