The following code will run flawlessly but at the end, Obj will still contain the assigned properties (.prop1 = 0 and .prop2 = "hello") and is not a new instance of ObjType. The attempt to assign a new instance of ObjType to obj has no effect as the reference to obj will be reverted to the original value when the code gets out of the With block.
With Obj
.prop1 = 0
.prop2 = "hello"
obj = new ObjType()
End With
Temporary folders are useful to store simple logs during execution of the program. It is also used for storing the decompressed files before any operation. The folder location varies from OS to OS. The following C# snippet would help in retrieving the Temporary folder path
string sPath;
sPath = Path.GetTempPath();
Console.WriteLine("Temporary Path := " + sPath );
Classes and structures can contain members that occupy less storage than an integral type. These members are specified as bit fields. The syntax for bit-field member-declarator specification follows:
declaratoropt : constant-expression
The declarator is the name by which the member is accessed in the program. It must be an integral type (including enumerated types). The constant-expression specifies the number of bits the member occupies in the structure. Anonymous bit fields — that is, bit-field members with no identifier — can be used for padding.
Note An unnamed bit field of width 0 forces alignment of the next bit field to the next type boundary, where type is the type of the member.
The following example declares a structure that contains bit fields
struct Date
{
unsigned nWeekDay : 3; // 0..7 (3 bits)
unsigned nMonthDay : 6; // 0..31 (6 bits)
unsigned nMonth : 5; // 0..12 (5 bits)
unsigned nYear : 8; // 0..100 (8 bits)
};
int main()
{
}
g_hIcon = (HICON)LoadImage((HINSTANCE)GetModuleHandle(IMAGENAME), MAKEINTRESOURCE(IDI_ICON1), IMAGE_ICON, 16, 16, LR_DEFAULTCOLOR);
DrawIcon(hdc, left, top, g_hIcon);
IMAGENAME is the name the the current DLL/EXE file. The icon must be created using VS resource editor and its ID set to IDI_ICON1
::GetModuleFileName(g_hInstDLL, szName, nSize);
::MessageBox(hwndParent, szName, _T(""), MB_OK);
where g_hInstDLL is the handle to the loaded module, usually available in the DLL entry point:
BOOL APIENTRY DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
//assign the handle here
g_hInstDLL = (HINSTANCE)hModule;
break;
}
return TRUE;
}
'If st is an empty string, e.g.:
Dim st as String = String.Empty
'The following returns TRUE:
Dim ok as Boolean = (st = Nothing)
'But this returns FALSE:
Dim ok as Boolean = (st is Nothing)
The "=" operator for String data type in VB.NET treats empty strings and null strings equally whereas the "is" operator treats strings as reference and does not care about the values. An empty string is not a null reference.
The following code will reboot the device abruptly without giving the user any prompt.
#define IOCTL_HAL_REBOOT CTL_CODE(FILE_DEVICE_HAL, 15, METHOD_BUFFERED, FILE_ANY_ACCESS)
extern "C" __declspec(dllimport) BOOL KernelIoControl(DWORD dwIoControlCode, LPVOID lpInBuf, DWORD nInBufSize, LPVOID lpOutBuf, DWORD nOutBufSize, LPDWORD lpBytesReturned);
//soft reset the device. Return true if OK, false if error
BOOL ResetDevice()
{
return KernelIoControl(IOCTL_HAL_REBOOT, NULL, 0, NULL, 0, NULL);
}
