Array's In C++

Array in C++

An array is a collection of similar data items stored at contiguous memory locations that can be individually referenced by adding an index to a unique identifier.

Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each value.

For example, an array containing 5 integer values of type int called foo could be represented as:

Where each blank panel represents an element of the array. In this case, these are values of type int. These elements are numbered from 0 to 4, with being 0 the first and 4 being the last.

Therefore, the foo array, with five elements of type int, can be declared as:

int arr [5];

Initializing arrays:

By writing int arr[ ]={ 1,3,5 }; , we are initializing the array.

We declare an array like int arr[3];, But we need to assign the values to it separately. Because 'int arr[3];' will definitely allocate the space of 3 integers in the memory but there are no integers in that.

To assign values to the array, assign a value to each of the elements of the array:

arr[0]=1;

arr[1]=3;

arr[2]=5;

It is the same like we are declaring some variables then assign values to them:

x=1;

y=2;

z=3;

Thus, there are two ways to initialize:

First

int arr[]={1,3,5};

and second is declaring the array first and then assigning the values to its elements.

int arr[3];

arr[0]=1;

arr[1]=3;

arr[2]=5;

Example:

#include <iostream>
int main(){

	using namespace std;

	int marks[3];
	float average;
	cout << "Enter first student marks" << endl;
	cin >> marks[0];
	cout << "Enter second student marks" << endl;
	cin >> marks[1];
	cout << "Enter third student marks" << endl;
	cin >> marks[2];

	average = ( marks[0] + marks[1] + marks[2] )/ 3.0;
	cout << "Average marks : " << average << endl;

	return 0;
}

Output:


Enter first student marks
63
Enter second student marks
58
Enter third student marks
44
Average marks : 55

Accessing arrays:

You access an array element by referring to the index number.

Array elements are accessed by using an integer index. Array index starts with 0 and goes to the size of the array minus 1.

The name which can be used to refer to each element is the following:

For example, the following statement stores the value 75 in the third element of arr[]:

arr [2]=36;

and, for example, the following copies the value of the third element of arr[] to a variable called x:

x=arr[2];

For example:

// arrays example
// assigning arr[] elements to the result variable
 
#include <iostream>
using namespace std;

int arr[] = {16, 2, 77, 40, 659};
int n, result=0;

int main ()
{
  for ( n=0 ; n<5 ; ++n )
  {
    result += arr[n];
  }
  cout << result;
  return 0;
}

There are three types of Arrays:

1. One Dimensional Array:

In this type of array, it stores elements in a single dimension. And, In this array, a single specification is required to describe elements of the array.

Following is an example of One-D array:

#include <iostream>
usin namesapce std;

int main()
{
	int arr[5]= {1,2,5,7,3};
	
	for(int i=0;i<5;i++)
	{
		cout<<arr[i]<<" ";        

	}
	return 0;
}

Output:

1 2 5 7 3

Two Dimensional Array:

In this, two indexes describe each element, the first index represents a row, and the second index represents a column.

Following is an example of 2D Array:

#include <iostream>
usin namesapce std;

int main()
{
	int arr[3][3]={{1,2,3},{2,4,6},{3,6,9}};
	
	for(int i=0;i<3;++i)
	{
		for(int j=0;j<3;++j)
		{
			cout<<arr[i][j]<<" ";
		}
		cout<<endl;
	}
	return 0;
}

Output:

1 2 3
2 4 6
3 6 9

Multidimensional Array:

A plain example of multidimensional array is a 2-d array. A two- dimensional array also falls under the category of multidimensional array. This multidimensional array can have any number of dimensions.

Syntax for declaring:

Datatype arr_nm[size1][size2]......[size n];

Example:

int array[5][10][4];

Array's In C++

Array in C++

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