Arrays in C++

Arrays is a kind of data structure that can store a elements of the same type.

Arrays stores the elements in a contiguous memory locations.

Array is a collection of variables of the same type.

 For example: we want to declare 100 integer variable

Instead of declaring 100 individual variables, such as

int number0, number1,number2,number3, … …., number99;

you declare one integer array variable such as

int number[100];

here number[100] is an integer array of size 100, means this array can store 100 integer value.

Array indexing starts from index 0 to n-1.

Means first integer number store in array number[0], second integer number store in array number[1], third integer number store in array number[2], and so on. Here 100th  number store in array numbers[99].

Array In C++

Declaring Arrays

Syntax of declare an array in C:

Data_type  arrayName [ arraySize ];

This is called a single-dimensional array.

The arraySize must be an integer constant greater than zero.

datatype can be any valid C data type.

Example: write a program to create integer array and store 5 integer number and print.  


Element Position in Array

Description : In the above program,   “int  num[5]” array can store 5 element in a contiguous memory locations from index 0 to 4.         

Example: Write a program to take 5 number from user and store integer number in integer array and print.  


Another way to Initialize Array

 We can also initialize array by this way:

int num[5] = { 54 , 4,  13,  2,  17 };

above integer array num[5], stores five numbers. Where num[0] store 54, num[1] store 4….. , & num[4] store 17.


Multi-dimensional Arrays 

C++  programming language also support multidimensional arrays.

Syntax of multidimensional array declaration:

Data_type    array_name[size1][size2]…[sizeN];

For example, if we want to creates a three dimensional integer array −

int  num[5][10][4];

Two-dimensional Arrays

The simplest form of multidimensional array is the two-dimensional array.

If we want to declare a two dimensional integer array of size [x][y] ( where x is a  number of rows and y is a number of columns ) you would write something as follows −

 int  a[3][4];

In the above line we have created two-dimensional integer array ”a” with 3 rows and 4 columns.

Two Dimensional Array

Initializing Two-Dimensional Arrays

In a C++ programming language  Multidimensional arrays may be initialized by specifying bracketed values for each row.

For example we want to create an integer array with 3 rows and each row has 4 columns.

Above the nested braces indicates the intended rows.

The following initialization is equivalent to the previous example −

int a[3][4] = {1,2,3,4,5,6,7,8,9,10,11,12};

which indicate the nested braces for intended row, are optional.

Accessing Elements of Two-Dimensional Array

Create a two-dimensional array of size 3*3 and  nested loop is used to handle a two-dimensional array −


Example: Write a program to create 3*3 matrix and take all elements of matrix as an input from user and print it.


Addition of Two Matrix

Example: Write a program to add two matrix.

Firstly, ask from user order of matrix( number of rows and column).

Then take the elements of matrix from user as a input and print the resultant matrix

For example, if a user input order as 3,3, i.e., three rows and three columns and

First matrix                      

1          2          3
4          5          6
7          8          9

Second matrix:

9          8          7
6          5          4
3          2          1

then the output of the program (addition of the two matrices) is:

10        10        10
10        10        10
10        10        10

Matrix addition program in C++


Matrix multiplication

Example: Write a program to multiply two matrix. Firstly, ask from user order of matrix( number of rows and column). Then take the elements of matrix from user as a input and print the resultant matrix.