//返回由上一个非托管函数返回的错误代码，该函数是使用设置了 -
//DllImport属性中SetLastError=true 标志的平台调用来调用的 int err = Marshal.GetLastWin32Error();
if (err != Win32Error.ERROR_INSUFFICIENT_BUFFER)
ThrowEnumPrinterException();
} iSize = iNeeded; if (iNeeded != 0)
{
try
{
//使用AllocHGlobal分配非托管内块
printers = Marshal.AllocHGlobal(new IntPtr(iSize));
//如果调用不成功抛出异常
if (!EnumPrinters(printerKind, String.Empty,1,printers, iSize, ref iNeeded, ref iReturned) )
{
ThrowEnumPrinterException();
}
else
{
pInfo = GetPrinterInfoFromMemory(printers, iReturned);
}
}
finally
{
//释放分配的内存块
if (printers != IntPtr.Zero)
Marshal.FreeHGlobal(printers);
}
}
return pInfo;
}
#endregion #region PrinterInfo
public struct PrinterInfo
{
public string Name;
public string Description;
public string Comment;
}
public sealed class Win32Error
{
private Win32Error() {}
public const int ERROR_INSUFFICIENT_BUFFER = 122;
}
#endregion #region EnumPrinters
[DllImport("winspool.drv", SetLastError = true, CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.Bool)] | 
