Programming Tutorials

Introduction to Arrays

By: aathishankaran in Java Tutorials on 2007-02-01  

Variables are used to hold data in memory. For every variable used, there should be and appropriate declaration. If 100 numbers are to be accepted, then 100 different variable declarations are required.

For example:

integer a1,a2,a3.a4,...,a100;

In many applications, more than 100 variables are required, in such cases, the entire task of variable declaration and working with the variables becomes quite inconvenient.

Arrays are the solution to this problem. They play an important role in problem-solving wherever a large number of variables are to be used.

An array is a group of elements that has a common name, and array elements are differentiated from one another by their positions within the array

Declaration Arrays

Arrays, like variable, should also be declared before being used, an array containing five elements, all of which are integers, can be declared as follow:

integer Num_array[5];

The name of the array cannot be the same as that of any other variable declared within the same program the size of the array, specified by the number 5 within square brackets, indicates how many elements are to be allocated to the array Num_array.

As with regular variables, the declaration does not assign values; it reserves memory for the array, the dimension used to declare an array must always be a positive integer constant.

The array subscript number starts from 0. Thus, the elements in the array Num_array are:


The following statements assign values to each element of integer array called Num_array:

Num_array[0] = 10;
Num_array[1] = 20;
Num_array[2] = 30;
Num_array[3] = 40;
Num_array[4] = 50;

Each element of an array can be referred anywhere in a program just like a variable.

An array name must be chosen according to the rules used for naming other variables.

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