Stack vs Array

Difference between Array and Stack

In this article, we are going to discuss the major differences between the stack and array data structures:

Array – In the data structure, the array is defined as the linear and ordered collection of data items of the same data types in which each data item is identified or accessed uniquely by its index in the array. It is also referred to as the primitive data type because it is predefined in different programming languages. The array is an idea to store the data items together in a continuous manner.

An array is declared as “data type array name [array size]”.

The indexing of each item and memory allocation is shown in the figure below:

Stack – In the data structure, the stack is defined as the non-primitive, linear and ordered collection of data items. In the stack, the addition of new data items and deletion of the existing data items are done from the one end of the stack, known as the top of the stack (TOS). The stack follows the LIFO (Last In First Out) or FIFO (First In Last Out) mechanism means the new newly added element will be removed first from the stack.

The most accessible element in the stack is the top element, and the least accessible element in the stack is the bottom element.

The diagrammatical representation of a stack is given below:

Now, let us see the major differences between these two data types:

S. No.	Array	Stack
1.	It is the linear and ordered collection of data items of the same data types where each item is identified uniquely by its index in the array.	It is also the linear and ordered collection of data items called abstract data type and follows the LIFO mechanism.
2.	It is referred to as a primitive data type because it is predefined.	It is referred to as the non-primitive data type because it is not predefined; instead, it is defined by the user to access the data objects in a LIFO manner.
3.	An array is only capable of data items of the same data types. To store data items of different data types, we need to create different arrays.	A stack is capable of storing data items of different data types.
4.	Each data item can be accessed randomly by its index value.	No random access is allowed in the stack. We can only access the top element of the stack.
5.	The basic operations performed on an array are read, write, update, etc.	The basic operations performed on a stack are push, pop, peek, etc.
6.	The insertion and deletion of elements can be done at any index.	The insertion and deletion of data items can only be done from one end, known as the top of the stack (TOS).
6.	The array has a fixed size allocated to it during the compile-time and cannot be changed during run time.	The stack may or may not have a fixed size (stack has a dynamic size). It allows us to increase the stack size during run time.
7.	We can perform search operations on it, such as linear and binary searches.	We can perform only linear search on it.
8.	We cannot implement using a stack.	We can implement a stack using arrays or linked lists.
9.	The memory allocated to an array is done continuously, and such allocation is referred to as the contiguous memory allocation.	The memory allocated to a stack can be continuous or discontinuous. The discontinuous memory allocation is referred to as the non-contiguous memory allocation.
10.	An array is used to implement heap, hash tables, stack, queue, maintain multiple variable names, perform matrix operations, for CPU scheduling, etc.	A stack is used to implement DFS (Depth First Search or Traversal) algorithm, evaluate arithmetic expressions, recursion, manage function calls, undo and redo operations, backward and forward operations in the browser, etc.
11.	An array can be 2D or 3D.	A stack can not be 2D or 3D because stacking means placing the data items at the top which do not exist in 2D and 3D.
12.	The address of each item can be calculated easily. The address of any item is equal to the base address + index of that item * size of each data item.	One cannot calculate the address of each data item in a stack
13.	On an array, we can perform sorting techniques like the bubble sort, heap sort, insertion sort, etc.	We can perform sorting techniques on a stack.