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An array is a contiguous block of memory containing one or more elements of the same type. The array identifier is a reference to that block of memory. References do not require any memory other than the memory they reference. References are not variables -- they are merely aliases for memory addresses.
A pointer is a variable that can store any reference and provides indirect access to that reference. Pointers can be used to allocate arrays dynamically, which means memory is required not only for the array, but also for the pointer to store the starting memory address of the array. Once allocated, the array can be referenced directly, but the pointer is still required in order to release the memory allocation when it is no longer required.
Arrays employ pointer arithmetic to locate individual elements by their zero-based index, which is essentially an offset from the reference multiplied by the size of the element type. However arrays and pointers are not the same from a programming standpoint. Your compiler may well implement references as pointers, but that is only of concern to compiler authors, not programmers.
Two-dimensional dynamic arrays make use of a pointer-to-pointer variable to point to a one-dimensional array of pointers, each of which points to a one-dimensional array of the actual elements. A three-dimensional array employs a pointer-to-pointer-to-pointer to point to a one-dimensional array of pointer-to-pointer variables, each of which points to a two-dimensional array. And so on. Static arrays use less memory as there is no need to maintain arrays of pointers, but static arrays are only useful when the number of elements and dimensions are known at compile time. At runtime, arrays of pointers are required over and above the array elements themselves, in order to both allocate and deallocate the memory, as well as obtain references to the elements in the array.
Pointers also have uses beyond that of dynamic arrays, including allocating any type of memory of any size, and pointing at functions which can then be passed as arguments to other functions.
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Passing an array name to a pointer assigns the first memory location of the array to the pointer variable?
Yes, passing an array name to a pointer assigns the first memory location of the array to the pointer variable. An array name is the same as a pointer to the first location of the array, with the exception that an array name is a r-value, while a pointer is an l-value.
What is a pointer in the array?
A pointer into an array of elements of type E is a pointer to a single element of type E:typedef ..... E;E array[123];E* const pointer = &array[18]; // points to the 19th element inside 'array'An array of pointers is an array whose elements are pointers:typedef .... E;E* array[123];E** const pointer = &array[18]; // points to the 19th pointer within 'array'Referencing the name of the array variable without use of the index operator itself is a constant pointer to its first element. Therefore, the following if-clause is always true:typedef .... E;E array[123];if (array &array[N]) { // ALWAYS true ...}
What is the difference bw function pointer and function of pointer?
function pointer is a variable that hold the address of any function which declared in the program but function pointer is the array of the function that accept the run time size of the function.
Why you use an array of pointer to pointer?
because u freakin can
What is the relationship between an array and a pointer?
All variable names are an alias for the value stored at the memory address allocated to them. To get the memory address itself, you must use the address of operator (&). The value returned from this can then be stored in a pointer variable.Arrays are different. The array name is an alias for the start address of the array, thus you do not need the address ofoperator to obtain the memory address (although you can if you want to). This means that when you pass an array name to a function, you pass the memory address of the array rather than passing the array itself (which would require the entire array to be copied, which is a highly inefficient way to pass an array). In essence, the array is passed by reference rather than by value.Consider the following code. This shows how a primitive variable name differs from the name of an array of primitive variables. The final portion shows how a pointer can be used to achieve the same results you got by accessing the array elements directly from the array name itself. This is in fact how the compiler implements arrays, using pointers, but there's no need to do this in your code. Accessing array elements directly by their index is a programming convenience.#include using namespace std;int main(){int i = 10;cout
Which two pointer does not increment or decrement in arithmetic array?
constant pointer and character pointer
Why can't we increment an array like a pointer?
once we initialize the array variable, the pointer points base address only & it's fixed and constant pointer
What is the difference between null array and an empty array?
There is no null array as such. However, a pointer to an array may be nullified (pointing to zero) before memory is allocated to it, or after that memory is released. But the same is true of any pointer. That is, the pointer is NULL, not what it previously pointed to. An empty array usually refers to a dynamic array for which no memory has yet been allocated (in other words, a null pointer). However, the term can also apply to static arrays or dynamic arrays that have been allocated memory, where every element is initialised with a value that has no significance. For instance, an array of natural numbers (positive integers greater than 0) might be initialised with the value 0 (a non-natural number) in every element to indicate that the array is empty. By contrast, individual elements could be set to zero to indicate which elements are available (an empty element as opposed to an empty array).
How do you return an array from function?
By returning a pointer to the first element of the array.
How do you convert from array notation to pointer notation?
In the C and C++ languages the array notation arr[i] is completely equivalent to the pointer notation *(arr + i).
What is pointer to a structure?
A pointer is a variable that holds address information. For example, in C++, say you have a Car class and another class that can access Car. Then, declaring Car *car1 =new Car() creates a pointer to a Car object.. The variable "car1" holds an address location.
What is the easiest way to pass arrays as argument in c?
the simple and efficient way to pass an array is pointer to an array like that int (*p)[30] ; // pointer to an array of integer having 30 element
