Array Representation in Data Structures

Representation of Array

The representation of an array can be defined by its declaration. A declaration means allocating memory for an array of a given size.

Array

Arrays can be declared in various ways in different languages. For better illustration, below are some language-specific array declarations.

C++

int arr[5];        // This array will store integer type element
char arr[10];    // This array will store char type element
float arr[20];  // This array will store float type element

C

int arr[5];        // This array will store integer type element
char arr[10];    // This array will store char type element
float arr[20];  // This array will store float type element

Java

/* Static Arrays are arrays that are declared before runtime
and are assigned values while writing the code.
*/

// The syntax of declaring a static array is:
<data type><variable name>[]
    = {<data1>, <data2>,…..<dataN> };

// Example:
int arr[] = { 2, 5, 6, 9, 7, 4, 3 };

Python

# Python code
arr = [10, 20, 30]  # This array will store integer
arr2 = ['c', 'd', 'e']  # This array will store characters
arr3 = [28.5, 36.5, 40.2]  # This array will store floating elements

C#

int[] arr = new int[5]; // This array will store integer type element

Javascript

// JS code
let arr=[10,20,30];  // This array will store integer
let arr2 = ['c', 'd', 'e'] // This array will store characters
let arr3 = [28.5, 36.5, 40.2] // This array will store floating elements

Array declaration

However, the above declaration is static or compile-time memory allocation, which means that the array element’s memory is allocated when a program is compiled.

Here only a fixed size (i,e. the size that is mentioned in square brackets []) of memory will be allocated for storage, but don’t you think it will not be the same situation as we know the size of the array every time, there might be a case where we don’t know the size of the array. If we declare a larger size and store a lesser number of elements will result in a waste of memory or either be a case where we declare a lesser size then we won’t get enough memory to store the rest of the elements. In such cases, static memory allocation is not preferred.