Windows Programming Interview Preparation Guide
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Windows programming Interview Questions and Answers will guide us now that windows API, informally WinAPI, is Microsoft's core set of application programming interfaces (APIs) available in the Microsoft Windows operating systems. It was formerly called the Win32 API; however, the name Windows API more accurately reflects its roots in 16-bit, so learn more about Windows programming with the help of this Windows programming Interview Questions with Answers guide

30 Windows Programming Questions and Answers:

1 :: What are types of kernel objects?

Several types of kernel objects, such as access token objects, event objects, file objects, file-mapping objects, I/O completion port objects, job objects, mailslot objects, mutex objects, pipe objects, process objects, semaphore objects, thread objects, and waitable timer objects.
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2 :: If we cannot alter these Kernel Object structures directly, how do our applications manipulate these kernel objects?

The answer is that Windows offers a set of functions that manipulate these structures in well-defined ways. These kernel objects are always accessible via these functions. When you call a function that creates a kernel object, the function returns a handle that identifies the object.
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3 :: User can access these kernel objects structures?

Kernel object data structures are accessible only by the kernel
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4 :: How the handle helps in manipulating the kernel objects?

Whenever you call a function that accepts a kernel object handle as an argument, you pass the value returned by one of the Create* functions. Internally, the function looks in your process’s handle table to get the address of the kernel object you want to manipulate and then manipulates the object’s data structure in a well-defined fashion.
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5 :: You forget to call CloseHandle - will there be a memory leak?

Well, yes and no. It is possible for a process to leak resources (such as kernel objects) while the process runs. However, when the process terminates, the operating system ensures that any and all resources used by the process are freed—this is guaranteed. For kernel objects, the system performs the following actions: When your process terminates, the system automatically scans the process’s handle table. If the table has any valid entries (objects that you didn’t close before terminating), the system closes these object handles for you. If the usage count of any of these objects goes to zero, the kernel destroys the object.
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6 :: What is a kernel object?

Each kernel object is simply a memory block allocated by the kernel and is accessible only by the kernel. This memory block is a data structure whose members maintain information about the object. Some members (security descriptor, usage count, and so on) are the same across all object types, but most are specific to a particular object type. For example, a process object has a process ID, a base priority, and an exit code, whereas a file object has a byte offset, a sharing mode, and an open mode.
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7 :: Name few functions that create Kernel Objects?

HANDLE CreateThread(…),HANDLE CreateFile(..),HANDLE CreateFileMapping(..)HANDLE CreateSemaphore(..)etcAll functions that create kernel objects return process-relative handles that can be used successfully by any and all threads that are running in the same process.
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8 :: How to identify the difference between the kernel object and user object?

The easiest way to determine whether an object is a kernel object is to examine the function that creates the object. Almost all functions that create kernel objects have a parameter that allows you to specify security attribute information.
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9 :: How does the kernel object outlive the process that created it?

If your process calls a function that creates a kernel object and then your process terminates, the kernel object is not necessarily destroyed. Under most circumstances, the object will be destroyed; but if another process is using the kernel object your process created, the kernel knows not to destroy the object until the other process has stopped using it
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10 :: What is signaled and non signaled state?

An event is in signaled state means that it has the capacity to release the threads waiting for this event to be signaled. An event is in non signaled state means that it will not release any thread that is waiting for this particular event.example in our project: when user clicks the image application icon double simultaneously. Two image application windows were created. so PAIG created an event and set it to non-signaled state. Then the image application will reset the event to signaled state, after this all the threads are released.
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