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A touchpad is a small, flat, rectangular pointing device that is sensitive to pressure and motion. To move the pointer using a touchpad, slide your fingertip across the surface of the pad. Some touchpads have one or more buttons around edge of the pad that work like a mouse buttons.

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Abdul Hamid

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What is falloc?

falloc is a function similar to malloc. Where the function malloc returns a pointer to an area of memory, falloc returns a "far" pointer to a "far" area of memory; i.e., memory that goes beyond the segmented memory limitations inherent to x86 memory architecture.


What is the difference between uninitialized pointer and null pointer in c language?

A null pointer is a pointer that has been initialised with the NULL value (zero). An uninitialised pointer is one that has not be initialised to any value and will in fact store whatever value happened to reside in the pointer's own memory address at the point of instantiation. Uninitialised pointers are a clear sign of bad programming because the only safe way to determine if a pointer is valid or not is to compare its value with NULL. An uninitialised pointer will almost always be non-NULL, which means you run the risk of accessing memory that either does not belong to you, or is otherwise invalid. Most compilers include a debug switch to warn you when you attempt to access any uninitialised variable, which naturally includes pointer variables. This switch must be on at all times.Whenever you instantiate a pointer, always initialise it straight away, either by nullifying it, or by storing a valid memory address in it. When you are finished with the pointer, it's good practice to nullify it immediately, even if the pointer would subsequently fall from scope. If the pointer is to be immediately re-assigned, there is no need to nullify it (but it's good practice nonetheless). If you follow this practice at all times, you can be assured that any non-NULL pointer will always be pointing at something valid (and if it isn't, then you have some serious problems elsewhere in your code).As a rule of thumb, if you can use a reference rather than a pointer, use a reference. They are much easier to work with. Pointers should only be used if there's any possibility (however remote) that a reference could be NULL, because a NULL reference will completely invalidate your program (pointers can be NULL, but references can never be NULL). This is why functions such as malloc() and calloc(), and the C++ new operator all return pointers rather than references. You can only return a reference when an allocation is guaranteed to succeed, and a dynamic memory allocation simply cannot make that guarantee.


What is memory allocation in c plus plus?

Whenever we instantiate an object of type T, we must allocate sizeof(T) bytes to that object. When that object falls from scope, the memory it occupied is released back to the system. In most cases this is done for us, automatically, thus we don't often consider the memory allocations and deallocations going on behind the scenes. However, in order to make best use of memory, it is vital to know exactly where and when every allocation occurs, and when that memory is released. In C++ there are generally 4 areas of memory to consider. The code area is the area that contains our program's machine code. In essence, this is the area where our program's functions reside. The next area is called the global area, which is essentially where our static allocations reside. The next area is the call stack, or simply the stack. This is the area where we do most of our work, it is where scoped variables are automatically allocated and released. The final area is the heap or free store. Unlike the other areas, which have a fixed size, the heap gives us the freedom to utilise as much memory as we need for any purpose we desire (within the limitations of the platform). In order to do so we must allocate that memory as and when it is needed and release it when it is no longer required. In order to allocate memory on the heap, we must use the new operator. To release the memory, we use the delete operator. We can also instantiate and release arrays of objects using the new [] and delete [] operators. We can also use the C-style functions, malloc and free, to achieve the same thing. However, it's important to note that when malloc is used to instantiate an object of a class, the object's constructor (if it has one) is not invoked as it is with new. Moreover, malloc returns a void pointer (void*) which must subsequently be cast to the appropriate type before it can be used. You must also be careful not to delete memory allocated with malloc, or to free memory allocated with new. The same restrictions apply to the other C-style allocators, calloc and realloc. Although you are free to use these C-style functions if you wish, they are best avoided as they offer no advantages over the new operator. The new operator is a unary operator. Its only argument is the type of memory we wish to allocate. The return value is a pointer of that type. However, the return value is temporary. If we don't immediately assign that value to a local pointer of the same type, the memory address will be lost. And if we lose the memory address, there's no way to release the allocation -- resulting in a memory leak. For example, is we wish to allocate memory for an int, we would use the following statements: int* p = new int; // use p... delete p; It is important to note that we've actually got two variables here, not one. The first is the pointer named p. The second is the integer itself. However, the integer has no name of its own, so the only way we can refer to it is by dereferencing p. It's also important to note that p can fall from scope before we've deleted the memory it points to. Although that's usually bad, it is sometimes necessary if we want the allocated memory to exist beyond the scope of the pointer. Fortunately, we do not need the pointer itself, we only need the memory address stored in the pointer. Thus we often encounter functions similar to the following: int* allocate (int value=0) { int* p = new int {value}; return p; } Note that p will fall from scope when this function returns, but its value will not -- provided we immediately assign that return value to another pointer: void foo () { int* ptr = allocate (42); // use ptr... delete ptr; } Although these functions are trivial, you should avoid using these types of function as ownership of the memory is vague at best. For instance, if you have two pointers pointing at the same address, neither pointer can be said to own the memory. And if you delete one of those pointers, the other is immediately invalidated. In general, the function that allocates memory should also be responsible for deallocating that memory. But sometimes that's neither possible nor desirable. However there are ways to define ownership of a raw pointer, using smart pointers and resource handles. Smart pointers are classes that encapsulate a pointer and behave exactly like the pointer. There are generally two types of smart pointer: unique and shared. When a unique pointer falls from scope, it automatically releases the memory being pointed to. This has the advantage that you no longer have to remember to delete the pointer when you're finished with it (indeed, smart pointers simply won't allow you to delete the encapsulated pointer). This is fine when ownership of the memory can be confined to a single scope. But for memory where ownership is harder to define, a shared pointer comes into its own. A shared pointer maintains a count of all instances of the shared pointer that refer to the same memory. As each comes into scope, the count is incremented and as each falls from scope the count is decremented. Only when the last instance falls from scope does the destructor finally release the memory. Resource handles are a bit like unique pointers in terms of memory ownership, however you don't use them as you would a pointer. This is because the memory being pointed to might move around. Consider an array. Whenever you need to add a new element to the end of an array you first need to reallocate the array to make space for the new element. This can result in the entire array being moved to new memory, in which case your original pointer is no longer valid. This is similar to how the C-style realloc function works with raw pointers. However, if you use a resource handle, the actual address is of no real concern to you. The resource handle takes care of the dynamic allocation and reallocation of the underlying memory for you. This is exactly how std::string and std::vector work.


Is pipe round because it provides the least surface area to volume ratio?

More likely because it's easier to manufacture, much easier to put threads on, you don't have to worry about orientation when you put them together, and they have no weak spots created by corners. My gutter pipes are rectangular because they don't stick out as far from the house as a circular one with the same area. But they are low enough in the pressure they contain that they can be formed from sheet metal with a crimped seam. Making a water supply pipe that way would be impossible. And it's easy to keep them aligned to the house. Running a rectangular water main under a street would be a major pain.


How pointer differs from normal variable?

Usual variable used so called value type mechanism, meaning that if you have passed the variable to a function the variable itself was not passed, only its copy. Which makes value type mechanism safe. The only problem is that you use a lot of memory because a copy of your variable has been created.Pointers allow to avoid creating copies and operate with addresses of variables. It means when you pass your variable to any function, you actually pass only the variable's address. This mechanism is called reference type.Pointers work much faster and allow to use memory more effectively. The only problem is you have to take extra care when you are working with pointers. Using pointers any area of memory including protected by OS can be accessed. Such event will cause "blue screen" (under windows).

Related Questions

Which has more surface area a rectangular prisms or rectangular pyramid?

For the same base dimensions (base area) and the same height, the rectangular prism has more surface area.


Surface area of rectangular pyramid?

Suppose that the area of the rectangular base is: lw then if the height is: h the surface area is: lw + lh + wh I believe that formula is for the surface area of a rectangular prism...


What is the whole number of a rectangular area 225yd?

what will be a whole number for an rectangular area of 225 yards?


What are the dimensions of two rectangular prisms with the same surface area?

Given the surface area of a rectangular prism, there are infinitely many rectangular prisms possible.


What is the suface area of a rectangular prism?

The suface are of a rectangular prism is the area of each face added together for a total.


What is Finger sticks?

Finger stick-- A technique for collecting a very small amount of blood from the fingertip area.


A rectangular prism has a volume of 90cm3 the area of the rectangular prism is 45cm2. What is the height of the rectangular prism?

2 cm


A rectangular prism has a volume of 90cm3 the area of the rectangular prism is 45cm2 What is the height of the rectangular prism?

2 cm


What is the suface area of a rectangular prism when l60 w24 h5?

i think it is that when a person asks what is the area of a rectangular prism you give them the answer


How do you find the volume of a rectangular prism if you know the area and height?

Volume of rectangular prism = area of base x height


How do you find the answer of the base area of a rectangular prism?

The base of a rectangular prism is a rectangle. The area of a rectangle is length times width.


What two different rectangular prisms have same surface area?

Given any rectangular prism, there are infinitely many other rectangular prisms with exactly the same surface area.