Arrays

 What are Arrays?

The arrays are a collection of elements of the same data type allocated in an adjacent memory location. It is a group of related data items having the same data type.

A collection of variables of the same type that are referred to using a common name is called an array and every element is access through an index associate with that element.

 

Why do we need arrays?

It helps to represent a large number of elements using a single variable. It also makes accessing elements faster easy to store in memory location using the index of the array that represents the location of an element in the array.

 

Declaration of array

The array must be declared before they are used. The general form of array declaration is,

data_type array_name[array_size];

Example

int marks[5];

 

Initialization of Array in C.

After declaring the array it must be initialized. 

Array declaration by initializing elements

int marks[]={20,30,40,50,60};  

 

Array declaration by specifying the size and initializing elements.

int marks[5]={20,30,40,50,60};  

 

Advantages of an Array

1. To sort the elements of the array, we need a few lines of code only.
2. Arrays represent multiple data items of the same type using a single name.
3. Traversal through the array becomes easy using a single loop.

 

Disadvantages of an Array

1. Insertion and deletion of elements can be costly since the elements are needed to be managed in accordance with the new memory allocation
2. The number of elements to be stored in an array should be known in advance.
3. Allocating more memory than the requirement leads to wastage of memory space and less allocation of memory also lead to a problem

 

Program in C

#include<stdio.h>  
int main(){      
int i=0;    
int marks[5]={20,30,40,50,60};   //declaration and initialization of array    
for(i=0;i<5;i++){      
printf("%d \n",marks[i]);    
}    
return 0;  
}

Output

20
30
40
50
60

 

 

Program in C++

#include <stdio.h>
 
int main()
{
    int arr[5];
    arr[0] = 5;
    arr[2] = -10;
    arr[3 / 2] = 2; // this is same as arr[1] = 2
    arr[3] = arr[0];
 
    printf("%d %d %d %d", arr[0],
           arr[1], arr[2], arr[3]);
 
    return 0;
}

Output

5 2 -10 5

Program in Python

import array as arr
 
a = arr.array('i', [1, 2, 3])
 
print ("The new created array is : ", end =" ")
for i in range (0, 3):
    print (a[i], end =" ")
print()
 
b = arr.array('d', [2.5, 3.2, 3.3])

print ("The new created array is : ", end =" ")
for i in range (0, 3):
    print (b[i], end =" ")

Output

The new created array is :  1 2 3 
The new created array is :  2.5 3.2 3.3

 

 

Program in Java

class GFG 
{
    public static void main (String[] args) 
    {         
      int[] arr;
          
      arr = new int[5];
          
      arr[0] = 10;
          
      arr[1] = 20;
          
      arr[2] = 30;
      arr[3] = 40;
      arr[4] = 50;
          
      for (int i = 0; i < arr.length; i++)
         System.out.println("Element at index " + i + 
                                      " : "+ arr[i]);          
    }
}

Output

Element at index 0 : 10
Element at index 1 : 20
Element at index 2 : 30
Element at index 3 : 40
Element at index 4 : 50

 

 

Operations in Array

• Insertion in array

• Deletion in array

• Traversing in array

• Searching in array

• Updation in array