Hello Everyone,
An array is a collection of items stored at contiguous memory locations. The idea is to store multiple items of the same type together. This makes it easier to calculate the position of each element by simply adding an offset to a base value, i.e., the memory location of the first element of the array (generally denoted by the name of the array). Each element can be uniquely identified by their index in the array (in a similar way as you could identify your friends by the step on which they were on in the above example). Arrays are among the oldest and most important data structures, and are used by almost every program. They are also used to implement many other data structures, such as lists and strings. They effectively exploit the addressing logic of computers. In most modern computers and many external storage devices, the memory is a one-dimensional array of words, whose indices are their addresses. Processors, especially vector processors, are often optimized for array operations.
Arrays are useful mostly because the element indices can be computed at run time. Among other things, this feature allows a single iterative statement to process arbitrarily many elements of an array. For that reason, the elements of an array data structure are required to have the same size and should use the same data representation. The set of valid index tuples and the addresses of the elements (and hence the element addressing formula) are usually, fixed while the array is in use.
Array’s size
In C language array has a fixed size meaning once the size is given to it, it cannot be changed i.e. you can’t shrink it neither can you expand it. The reason was that for expanding if we change the size we can’t be sure ( it’s not possible every time) that we get the next memory location to us as free. The shrinking will not work because the array, when declared, gets memory statically, and thus compiler is the only one to destroy it.
Types of indexing in an array:
0 (zero-based indexing): The first element of the array is indexed by a subscript of 0
1 (one-based indexing): The first element of the array is indexed by the subscript of 1
n (n-based indexing): The base index of an array can be freely chosen. Usually, programming languages allowing n-based indexing also allow negative index values, and other scalar data types like enumerations, or characters may be used as an array index.