What Is Memory Allocation and Deallocation in Data Structure?


Larry Thompson

What Is Memory Allocation and Deallocation in Data Structure?

Memory allocation and deallocation are essential concepts in data structures. They involve the dynamic management of memory during program execution. Understanding how memory allocation and deallocation work is crucial for efficient memory utilization and preventing memory-related issues such as memory leaks or segmentation faults.

Memory Allocation

Memory allocation refers to the process of reserving a portion of the computer’s memory for storing data during program execution. In data structures, memory allocation is typically required for creating and manipulating various data structures such as arrays, linked lists, trees, etc.

There are two primary methods of memory allocation:

  • Static Memory Allocation:

In static memory allocation, the size of the allocated memory is determined at compile-time or before the program execution starts. This type of allocation is used when the size of the data structure is fixed and known in advance. Examples include declaring an array with a specific size or allocating space for a fixed number of nodes in a linked list.

  • Dynamic Memory Allocation:

In dynamic memory allocation, the size of the allocated memory can be determined at runtime. This allows flexibility in managing variable-sized data structures that may change during program execution. Dynamic memory allocation is commonly used when dealing with unknown or changing sizes, such as input from user interactions or dynamic growth requirements.

The malloc() Function

In many programming languages like C and C++, dynamic memory allocation can be accomplished using functions like malloc(), calloc(), or new.

The malloc() function allocates a block of memory of a specified size in bytes and returns a pointer to the allocated memory. This memory is typically uninitialized, meaning it can contain garbage values until explicitly assigned.

For example, the following code allocates memory for an integer array of size 10:

int* arr = (int*)malloc(10 * sizeof(int));

Note: It’s important to check if the allocation was successful by verifying if the returned pointer is not NULL.

Memory Deallocation

Memory deallocation, also known as memory freeing or deallocation, is the process of releasing previously allocated memory back to the system so that it can be reused by other parts of the program or other programs running on the computer.

The free() Function

In languages like C and C++, when dynamic memory allocation is used, it’s essential to deallocate the allocated memory once it’s no longer needed. The free() function is used for this purpose.

To deallocate a dynamically allocated block of memory, simply pass the pointer to that block to the free() function. For example:


Note: It’s crucial to deallocate dynamically allocated memory to avoid memory leaks. Failing to deallocate memory can result in unnecessary consumption of system resources and ultimately lead to program crashes or performance issues.


In summary, understanding memory allocation and deallocation is vital for efficient programming and managing data structures effectively. By allocating only the necessary amount of memory during runtime and properly deallocating it when no longer required, you can optimize your program’s performance and avoid potential issues related to memory management.

Discord Server - Web Server - Private Server - DNS Server - Object-Oriented Programming - Scripting - Data Types - Data Structures

Privacy Policy