GetPrinter function fails to retrieves the printer information. [modified]

[Gokul_md]

Hi Please help me to find out the problem in GetPrinter function. First I am trying to get the printer handle for the specified printer using OpenPrinter function. . HANDLE hPrinter = 0; OpenPrinter ((LPTSTR)(LPCTSTR)strPrinterAddress, &hPrinter, NULL); This function gets succeed. Using this printer handle I am trying to access the specified printer information’s using the GetPrinter function. GetPrinter(hPrinter, 2, NULL, 0, &dwNeeded); if(!dwNeeded) { DWORD dwError = ::GetLastError(); ClosePrinter( hPrinter ); } Even using GetLastError() function I am not able retrieve error message. This function is not failing all the times. When I am trying to print out of 10 times, 6 times the printing is succeed. Only 4 times it’s getting failed. Please help me shoot out this problem. Thanks Gokul

modified on Tuesday, October 14, 2008 4:08 AM

[CPallini]

Why do you check dwNeeded instead of GetPrinter return value? What is GetLastError return value when GetPrinter fails? :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

[Gokul_md]

The Get Printer function will return required buffer size in dwNeeded. I hope this should always be greater than zero. So I checked with the buffer size. When I am trying to print the last error code it is printed nothing (empty).

[CPallini]

I would check the GetPrinter return value, and call GetLastError only when it fails. Are you aware that (MSDN [^]): Remarks Security Alert The pDevMode member in the PRINTER_INFO_2, PRINTER_INFO_8, and PRINTER_INFO_9 structures can be NULL. When this happens, the printer is unusable until the driver is reinstalled successfully. ? :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]

[David Crow]

Gokul_md wrote:

GetPrinter(hPrinter, 2, NULL, 0, &dwNeeded); if(!dwNeeded) { DWORD dwError = ::GetLastError(); ClosePrinter( hPrinter ); }

This should be:

if (! GetPrinter(hPrinter, 2, NULL, 0, &dwNeeded))
{
DWORD dwError = GetLastError();
FormatMessage(..., dwError, ...);
}

ClosePrinter(hPrinter);

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

[Gokul_md]

Yes i have formated the dword error code to string in the above mentioned way only. but it return the empty string.

[David Crow]

Gokul_md wrote:

Yes i have formated the dword error code...

What was its value?

Gokul_md wrote:

...but it return the empty string.

How are you verifying this?

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch

[Gokul_md]

i have formated the message using the below method. LPVOID lpMsgBuf; FormatMessage( FORMAT_MESSAGE_ALLOCATE_BUFFER | RMAT_MESSAGE_FROM_SYSTEM, NULL, dwError, MAKELANGID(LANG_NEUTRAL, LANG_DEFAULT), (LPTSTR) &lpMsgBuf, 0,NULL ); CString strMessage = (LPTSTR)lpMsgBuf; The error message is printed in the log file. FILE *fp = fopen("C:\\log.txt","a+"); fprintf(fp,"\n Error Occured - %s ", strMessage ); fclose(fp); in that log file it printer as Error Occured -

[David Crow]

What is the value of dwError?

"Love people and use things, not love things and use people." - Unknown

"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch