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From: hamishd on 7 Jan 2009 19:22 On Jan 8, 12:31 pm, "David Webber" <d...(a)musical-dot-demon-dot-co.uk> wrote: > "hamishd" <Hamish.D...(a)gmail.com> wrote in message > > news:dc1f26c5-6e3e-435a-9219-af0c908f09de(a)s9g2000prg.googlegroups.com... > > > > > Hi - sorry this is my 3rd question recently. I'm having trouble with > > strings and characters and unicode in general; can anybody suggest a > > good article to read which explains the basics? > > > My project is _UNICODE defined. However, a file I got from codeproject > > is not. Their code is below, but it cannot compile. > > > char szBuf[2001]; > > WORD cbBufMax = 2000; > > WORD cbBufOut; > > char *pszBuf = szBuf; > > > SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut); > > > I would have thought changing the char's to TCHAR's would fix.. > > however, I still get "error C2664: 'SQLGetInstalledDriversW' : cannot > > convert parameter 1 from 'char [2001]' to 'unsigned short *'" > > If you have TCHAR szBuf[2001] this should not happen. > > In a UNICODE build TCHAR is WCHAR and teh function call is to SQL...W(..) > In a non-UNICODE build it is CHAR and SQL....A(). > > Are you sure you have used TCHAR consistently? This is the entire function: // Get the name of the Excel-ODBC driver void CSpreadSheet::GetExcelDriver() { char szBuf[2001]; WORD cbBufMax = 2000; WORD cbBufOut; char *pszBuf = szBuf; // Get the names of the installed drivers ("odbcinst.h" has to be included ) if(!SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut)) { m_sExcelDriver = ""; } // Search for the driver... do { if( strstr( pszBuf, "Excel" ) != 0 ) { // Found ! m_sExcelDriver = CString( pszBuf ); break; } pszBuf = strchr( pszBuf, '\0' ) + 1; } while( pszBuf[1] != '\0' ); } The error message is the same regardless of whether or not i use TCHAR, WCHAR, or char.
From: Joseph M. Newcomer on 7 Jan 2009 19:55 See below... On Wed, 7 Jan 2009 15:19:17 -0800 (PST), hamishd <Hamish.Dean(a)gmail.com> wrote: >Hi - sorry this is my 3rd question recently. I'm having trouble with >strings and characters and unicode in general; can anybody suggest a >good article to read which explains the basics? > >My project is _UNICODE defined. However, a file I got from codeproject >is not. Their code is below, but it cannot compile. > > char szBuf[2001]; > WORD cbBufMax = 2000; > WORD cbBufOut; > char *pszBuf = szBuf; > > SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut); > >I would have thought changing the char's to TCHAR's would fix.. >however, I still get "error C2664: 'SQLGetInstalledDriversW' : cannot >convert parameter 1 from 'char [2001]' to 'unsigned short *'" **** Note that there are TWO symbols required: _UNICODE and UNICODE (without the _). BOTH need to be defined, or BOTH need to be not defined. If you only define _UNICODE, half of your interfaces will be wrong. joe **** > >Incidentally, I am trying to read data from an excel spreadsheet, and >trying the CSpreadSheet class from http://www.codeproject.com/KB/database/cspreadsheet.aspx. Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
From: Joseph M. Newcomer on 7 Jan 2009 20:28 I checked the header files; the documentation is wrong, and will shortly be added to my list of documentation errors. joe On Wed, 7 Jan 2009 15:57:14 -0800, "Tom Serface" <tom(a)nospam.camaswood.com> wrote: >The help for SQLGetInstalledDrivers says: > >BOOL SQLGetInstalledDrivers( > LPSTR lpszBuf, > WORD cbBufMax, > WORD * pcbBufOut); > >Indicating that you have to use a char buffer, but it looks like it's >calling a W flavor which seems odd.... Even the error you're getting >doesn't make sense because the first You might try something like: > > TCHAR szBuf[2001]; > WORD cbBufMax = 2000 * sizeof(TCHAR); > WORD cbBufOut; > LPTSTR *pszBuf = szBuf; // Not sure what you're using this for exactly >maybe you intended to pass this into the function instead? > >This link might have something useful for you. I admit I haven't used this >function so I'm sort of just guessing here. > >http://bugs.mysql.com/bug.php?id=35776 > >Tom > > >"hamishd" <Hamish.Dean(a)gmail.com> wrote in message >news:dc1f26c5-6e3e-435a-9219-af0c908f09de(a)s9g2000prg.googlegroups.com... >> Hi - sorry this is my 3rd question recently. I'm having trouble with >> strings and characters and unicode in general; can anybody suggest a >> good article to read which explains the basics? >> >> My project is _UNICODE defined. However, a file I got from codeproject >> is not. Their code is below, but it cannot compile. >> >> char szBuf[2001]; >> WORD cbBufMax = 2000; >> WORD cbBufOut; >> char *pszBuf = szBuf; >> >> SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut); >> >> I would have thought changing the char's to TCHAR's would fix.. >> however, I still get "error C2664: 'SQLGetInstalledDriversW' : cannot >> convert parameter 1 from 'char [2001]' to 'unsigned short *'" >> >> Incidentally, I am trying to read data from an excel spreadsheet, and >> trying the CSpreadSheet class from >> http://www.codeproject.com/KB/database/cspreadsheet.aspx. Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
From: Joseph M. Newcomer on 7 Jan 2009 20:27 See below... On Wed, 7 Jan 2009 16:22:20 -0800 (PST), hamishd <Hamish.Dean(a)gmail.com> wrote: >On Jan 8, 12:31�pm, "David Webber" <d...(a)musical-dot-demon-dot-co.uk> >wrote: >> "hamishd" <Hamish.D...(a)gmail.com> wrote in message >> >> news:dc1f26c5-6e3e-435a-9219-af0c908f09de(a)s9g2000prg.googlegroups.com... >> >> >> >> > Hi - sorry this is my 3rd question recently. I'm having trouble with >> > strings and characters and unicode in general; can anybody suggest a >> > good article to read which explains the basics? >> >> > My project is _UNICODE defined. However, a file I got from codeproject >> > is not. Their code is below, but it cannot compile. >> >> > char szBuf[2001]; >> > WORD cbBufMax = 2000; >> > WORD cbBufOut; >> > char *pszBuf = szBuf; >> >> > SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut); >> >> > I would have thought changing the char's to TCHAR's would fix.. >> > however, I still get "error C2664: 'SQLGetInstalledDriversW' : cannot >> > convert parameter 1 from 'char [2001]' to 'unsigned short *'" >> >> If you have TCHAR szBuf[2001] this should not happen. >> >> In a UNICODE build TCHAR is WCHAR and teh function call is to SQL...W(..) >> In a non-UNICODE build it is CHAR and SQL....A(). >> >> Are you sure you have used TCHAR consistently? > >This is the entire function: > >// Get the name of the Excel-ODBC driver >void CSpreadSheet::GetExcelDriver() >{ > char szBuf[2001]; > WORD cbBufMax = 2000; > WORD cbBufOut; > char *pszBuf = szBuf; **** Apparently due to terminal brain damage on the part of the documentation team, the documentation specifies this as an LPSTR, and it should be an LPTSTR. Also, weirdly, it uses a WORD to define the length. Didn't anyone in the SQL group read that Win32 is now out? **** > > // Get the names of the installed drivers ("odbcinst.h" has to be >included ) > if(!SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut)) > { > m_sExcelDriver = ""; > } > > // Search for the driver... > do > { > if( strstr( pszBuf, "Excel" ) != 0 ) **** For a Unicode app, this should be _tcsstr, comparing to _T("Excel"), and strictly speaking this should be compared to NULL **** > { > // Found ! > m_sExcelDriver = CString( pszBuf ); > break; > } > pszBuf = strchr( pszBuf, '\0' ) + 1; **** A more serious question is why you have chosen random numbers like 2001, 2000, etc. To handle this correctly, you would typically do something like WORD buflen = START_BUF_LEN; CString drivers; m_sExcelDriver.Empty(); while(TRUE) { /* get list of drivers */ WORD cbBufMax = buflen; LPTSTR szBuf = drivers.GetBuffer(buflen); if(!SQLGetInstalledDrivers(szBuf, buflen, &cbBufMax)) { drivers.ReleaseBuffer(); return; } if(cbBufMax == buflen - 1) { /* was truncated */ buflen *= 2; continue; } /* was truncated */ drivers.ReleaseBuffer(); break; } /* get list of drivers */ Assuming that any randomly-chosen value will be correct is not safe. The above loop is the standard pattern for an API that can truncate without giving an error. // Now a more serious question is whether or not there can be multiple drivers // that contain the word "Excel", but I'm assuming you will accept the first one LPTSTR szBuf = drivers.GetBuffer(); while(_tcslen(szBuf) > 0) { /* scan buffer */ if(_tcsstr(szBuf, _T("Excel") != NULL) { /* found one */ m_sExcelDriver = CString(szBuf); break; } /* found one */ szBuf += _tcslen(szBuf); } /* scan buffer */ drivers.ReleaseBuffer(); } **** > } > while( pszBuf[1] != '\0' ); **** It is not clear why there is a while-condition here...just test the string length as shown above. joe **** >} > >The error message is the same regardless of whether or not i use >TCHAR, WCHAR, or char. Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
From: hamishd on 7 Jan 2009 21:46
On Jan 8, 1:55 pm, Joseph M. Newcomer <newco...(a)flounder.com> wrote: > See below... > > > > On Wed, 7 Jan 2009 15:19:17 -0800 (PST), hamishd <Hamish.D...(a)gmail.com> wrote: > >Hi - sorry this is my 3rd question recently. I'm having trouble with > >strings and characters and unicode in general; can anybody suggest a > >good article to read which explains the basics? > > >My project is _UNICODE defined. However, a file I got from codeproject > >is not. Their code is below, but it cannot compile. > > > char szBuf[2001]; > > WORD cbBufMax = 2000; > > WORD cbBufOut; > > char *pszBuf = szBuf; > > > SQLGetInstalledDrivers(szBuf,cbBufMax,& cbBufOut); > > >I would have thought changing the char's to TCHAR's would fix.. > >however, I still get "error C2664: 'SQLGetInstalledDriversW' : cannot > >convert parameter 1 from 'char [2001]' to 'unsigned short *'" > > **** > Note that there are TWO symbols required: _UNICODE and UNICODE (without the _). BOTH > need to be defined, or BOTH need to be not defined. If you only define _UNICODE, half of > your interfaces will be wrong. Thanks Joe. |