This unit discussed about data structure called Arrays. The easiest form of array is a one-dimensional array which may be described as a finite ordered set of homogeneous elements that is stored in contiguous memory locations. For instance, an array might contain all integers or all characters or any data type, but might not contain a mix of data types.

The common form for declaring a single dimensional array is following:

data_type array_name[expression];

where data_type represents data type of the array. That is, char, integer, float etc. array_name is the name of expression and array which denoted the number of elements in the array.

For instance, assume the following C declaration:

int  a[100];

This declares an array of 100 integers.

The amount of storage needed to hold an array is related to its type and size directly. For a single dimension array, the overall size in bytes needed for the array is computed as illustrated below.

Memory needed (in bytes) = size of (data type) X length of array

The primary array index value is referred to as its lower bound & in C this is always 0 and the maximum index value is called as its upper bound. In the array the number of elements, called its range is given by upper bound-lower bound.

In the arrays we store values during program execution. Now Let us see the process of initializing an array while declaring it.

int a[4] = {34,60,93,2};

int b[] = {2,3,4,5};

float c[] = {-4,6,81,- 60};

We come to the following facts from these instance:

(i) If at the time of declaration the array is initialized, then the dimension of the array is optional.

(ii) Till the elements of array are not given any particular values, they have garbage values.