ARRAY

An array in C or C++ is a collection of items stored at contiguous memory locations and elements can be accessed randomly using indices of an array. They are used to store similar type of elements as in the data type must be the same for all elements.

Arrays are widely used data type in ‘C’ language. It is a collection of elements of similar data type. These similar elements could be of all integers, all floats or all characters.

An array of character is called as string whereas and array of integer or float is simply called as an array.

So array may be defined as a group of elements that share a common name and that are defined by position or index. The elements of an arrays are store in sequential order in memory.

There are mainly two types of Arrays are used:

 

●       One dimensional Array

●       Multidimensional Array

One dimensional Array

The syntax to declare single dimension array is:

datatype   arrayname[size];

The declaration

                    int a[10];

declares an array, named a, consisting of ten elements, each of type int.

We can represent the array a above with a picture like this:

The first element of the array is a[0], the second element is a[1], etc. For example:

            a[0] = 10;

            a[1] = 20; 

Array Initialization

It is possible to initialize some or all elements of an array when the array is defined.

The syntax looks like this:

            int a[10] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

The list of values, enclosed in braces {}, separated by commas, provides the initial values for successive elements of the array.

For example, it's common to loop over all elements of an array:

            int i;

            for(i = 0; i < 10; i = i + 1)

                        a[i] = 0;

This loop sets all ten elements of the array a to 0.

To set all of the elements of an array to some value, you must do so one by one, as in the loop example above. To copy the contents of one array to another, you must again do so one by one:

            int b[10];

            for(i = 0; i < 10; i = i + 1)

                        b[i] = a[i];

 

Multidimensional Array

The syntax to declare a double dimension array is:

datatype  arrayname[rowsize][columnsize];

The declaration of an array of arrays looks like this:

            int  a[5][7];

Initialization of  Array:

There are two ways to initialize a two Dimensional arrays during declaration.

int disp[2][4] = {

    {10, 11, 12, 13},

    {14, 15, 16, 17}

}; 

OR

int disp[2][4] = { 10, 11, 12, 13, 14, 15, 16, 17};

For accessing a two dimensional array a pair of nested loop is used as follows:

 

for (i = 0; i < 5; i = i + 1)

                        {

                        for (j = 0; j < 7; j = j + 1)

                                    printf ("%d\t", a2[i][j]);

                        printf ("\n");

                        }