Meaning something to the effect that you can't really clearly see what its pointing at. Only Windows knows that. One thing about it, as Disch said, is that its oftentimes passed to various Api functions that work with a window in some way, and I don't believe I've ever seen it as anywhere but in the first position as a function parameter.
That analogy actually works very well. The HWND parameter identifies the actual instance of some Window Class to which some operation is to be performed, as is exactly the case with the implicit 'this' pointer.
So there you have possibly the true significanse of HWNDs. Mar 14, at pm UTC. Improve this answer. Matthew Iselin Matthew Iselin 9, 3 3 gold badges 48 48 silver badges 60 60 bronze badges. A Handle can be useful for saving states among others. If u have data in a structure like an std::vector. Your object may be at different memory locations at different times during execution of a program, which means your pointer to that memory will change values.
With a handle it never changes, it always references your object. Imagine saving a state of a program like in a game - you wouldn't save out a pointer location to data and later import the data again and try to get that address in memory. You can however save out a Handle with your data, and import the data and handle. That is the correct answer, that they can be anything, and that the code that uses them defines the type of the handle. I tried to make a more concise version of my own similar answer, couldn't help myself, for posterity.
CornelVerster - They are the same in linux. I mean, not OS handles, but the concept. So, it depends on the handle as to its migration, or even need to migrate. Matthew Iselin: in any API documentation, do they define that thing is a handler then we should know to pass them to functions, otherwise how we can know what is a handler in API documentation — Amin Khormaei.
A handle is a sort of pointer in that it is typically a way of referencing some entity. Deltics Deltics 21k 2 2 gold badges 39 39 silver badges 67 67 bronze badges. Johannes Schaub - litb Johannes Schaub - litb k gold badges silver badges bronze badges. A handle is whatever you want it to be. A handle can be a unsigned integer used in some lookup table.
A handle can be a pointer to, or into, a larger set of data. It depends on how the code that uses the handle behaves. That determines the handle type. Pang 8, gold badges 82 82 silver badges bronze badges. The range is 0 through decimal. An unsigned INT An unsigned LONG. An unsigned LONG A bit Unicode character. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. Skip to main content.
This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Is this page helpful? Yes No. Any additional feedback? Skip Submit. The calling convention for system functions.
This type is declared in WinDef. An atom. For more information, see About Atom Tables. This type is declared in WinNT. A byte 8 bits. The calling convention for callback functions. The red, green, blue RGB color value 32 bits. A variable whose value is to remain constant during execution. A bit unsigned integer. This type is declared in IntSafe. An unsigned long type for pointer precision. Use when casting a pointer to a long type to perform pointer arithmetic.
Also commonly used for general bit parameters that have been extended to 64 bits in bit Windows. This type is declared in BaseTsd. A floating-point variable. A handle to an accelerator table. Half the size of a pointer. A handle to an object. A handle to a dynamic data exchange DDE conversation. However, the variable points to the entire object, cannot point to a member of the object, and it does not support pointer arithmetic.
The compiler uses the COM reference counting mechanism to determine if the object is no longer being used and can be deleted. This is possible because an object that is derived from a Windows Runtime interface is actually a COM object. The reference count is incremented when the object is created or copied, and decremented when the object is set to null or goes out of scope.
If the reference count goes to zero, the object is automatically and immediately deleted. The advantage of the handle declarator is that in COM you must explicitly manage the reference count for an object, which is a tedious and error prone process.
That is, to increment and decrement the reference count you must call the object's AddRef and Release methods. However, if you declare an object with the handle declarator, the compiler generates code that automatically adjusts the reference count. For information on how to instantiate an object, see ref new.
The system uses the CLR garbage collector mechanism to determine if the object is no longer being used and can be deleted. The common language runtime maintains a heap on which it allocates objects, and uses managed references variables in your program indicate the location of objects on the heap.
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