Arrays: Concepts and Needs

ARRAYS‒CONCEPTS

Many applications require the processing of multiple data items that have common characteristics. In such a situation, it is convenient to place such data items in an Array.

An array is a collection of similar data items, that are stored under a common name. A value in an array is identified by index or subscript enclosed in square brackets with array name.

The individual data items can be integers, floating point numbers and characters and so on, but they must be the same type and same storage class.

Each array element is referred by specifying the array name with subscript, each subscript enclosed in square brackets and each subscript must be a non‒negative integer.

Thus 'n' elements array 'Q' and the elements are

Q[0], Q[1], Q2], Q[3],..., Q[n‒1]

The value of each subscript can be expressed as an integer constant or an integer variable or an integer expression.

The arrays can be used to represent not only simple list of value but also task of data items in two, three or more dimensions.

NEEDS OF AN ARRAY

The C Language has the capability that enables us to define a set of similar data items known as an array.

Suppose you have a set of marks that you want to read into the computer, and to perform some operations on these marks, such as rank them in ascending order, compute their average, or find their median.

If you think about the process of ranking a set of marks, you quickly realize that you cannot perform such an operation until each and every grade has been entered. Therefore, using the techniques described previously, you would read in each marks and store it into a unique variable, perhaps with a sequence of statements such as the following:

printf ("Enter marks1\n");

scanf("%i", &marks1);

printf ("Enter marks 2\n");

scanf ("%i", &marks2);

printf ("Enter marks 3\n");

scanf("%i", &marks3);

After the marks have been entered, you can then proceed to rank them. This can be done by setting up a series of if statements to compare each of the values to determine the smallest grade, the next smallest grade, and so on, until the maximum grade has been determined.

If you try to write a program to perform precisely this task, you soon realize that for any reasonably sized list of marks, the resulting program is quite large and complex. All is not lost, however as this is one instance in which the array comes to the rescue.

Arrays can be classified into

• One‒Dimensional arrays

• Two‒Dimensional arrays

• Multi‒Dimensional arrays