How arrays used in vc plus plus?

Answer 1

Arrays are used to store two or more variables of the same type in contiguous memory. Since all elements are of the same type, they are also of the same size (in bytes), thus every element can be accessed as an offset from the start of the array. In an array of n elements, index 0 is the first element and index n-1 is the last element. By multiplying the index by the type size, the compiler can determine the start address of each element, thus permitting constant time, random access to any element within the array, as well as bi-directional traversal of the array.

Arrays provide the most compact method of storing multiple values of the same type. So long as you know the start address of the array (which is obtained by the array name alone) and the number of elements in the array (which must be stored separately), you can access any element in constant time.

C++ supports fixed-length arrays (std::array) and variable-length arrays (std::vector) as well as C-style arrays (both static and dynamic). In most cases you will use std::vector and std::array as they both provide bounds-checking, can be easily passed to functions by value, reference or pointer, and you enlist the compiler to ensure type safety. Both std::vector and std::array encapsulate the array, its type and its size, while std::vector uses a built-in memory manager to minimise reallocation of the array.

With C-style arrays, the onus is entirely upon the programmer to ensure bounds-checking and type safety are adhered to. In particular, passing a C-style array to a function via a pointer should be avoided as the function has no way to determine how many elements are actually in the array, let alone what type of elements were originally placed in the array.