Difference Between Static and Dynamic Memory Allocation

By Aina Parasher|Updated : April 19th, 2022

Difference Between Static and Dynamic Memory Allocation: Memory allocation is the process of allocating physical or virtual memory space to computer programs and services. Memory allocation takes place either before or during program execution. Memory allocations are divided into two categories:

  1. Static Memory Allocation or Compile-time Memory Allocation
  2. Memory Allocation at Runtime or Dynamic Memory Allocation

The key difference between static and dynamic memory allocation is that in static memory allocation memory is allocated at compile time, once the memory is allocated, the memory size is fixed and can not be changed. In dynamic memory allocation, memory is allocated at runtime using calloc(), malloc(), and once the memory is allocated, the memory size can be changed. Let’s discuss some major differences between static and dynamic memory allocation in the sections below.

Table of Content

What is Static Memory Allocation?

When you use Static Memory Allocation, the memory for your data is allocated at the start of the application. When the program is created, the size is set. It applies to variables in the global scope, variables in the file scope, and variables qualified by static defined inside functions. This memory allocation is set in stone and cannot be altered, i.e. increased or lowered once it has been allocated. As a result, precise memory needs must be understood ahead of time.

  • Memory is allocated during the compilation process.
  • It makes use of a stack to keep track of the memory allocation.
  • The memory size of this allocation cannot be changed once it has been allocated.
  • It is ineffective.

Static memory allocation occurs when the ultimate size of a variable is chosen before the program is performed. Compile-time memory allocation is another name for it.

What is Dynamic Memory Allocation?

The technique of assigning memory space during execution or run time is known as dynamic memory allocation. The advantages of allocating memory dynamically are mentioned below.

  • When we don't know how much memory will be required for the software ahead of time.
  • When we need data structures that don't have a memory restriction.
  • When you wish to make better use of your memory space.
  • Dynamic memory allocation is required when using the concepts of structures and linked lists in programming.

Difference Between Static and Dynamic Memory Allocation

A quick introduction to static and dynamic memory allocation has been provided. Now we'll look at the distinction between static and dynamic memory allocation. The following table summarises the significant distinctions between these two memory allocations:

Static Memory AllocationDynamic Memory Allocation
Static memory refers to memory allocation that occurs during the compilation process.Dynamic memory allocation refers to memory allocation that occurs during the execution or runtime of a program.
It makes use of a stack to manage memory allocation that is static. It makes use of a heap to manage dynamic memory allocation.
It is less efficient.It is more efficient.
Once the memory has been allocated, it will be available throughout the application.Memory can be allocated at any point throughout the application.
It is faster than dynamic memory allocation.It is slower than static memory allocation.
The memory in a static memory allocation cannot be altered while the application is running.During the execution of a program, dynamic memory allocation allows the memory to be altered.

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FAQs

  •  The basic difference between static and dynamic memory allocation is that memory allocation is done at the execution time in dynamic and memory allocation is done in a compile-time in static memory allocation.

  • The difference between static and dynamic memory allocation in terms of speed is such that the dynamic memory allocation is considered slower than the static memory allocation.

  • Static memory allocation is a memory allocation strategy in which the operating system allocates a predetermined amount of memory during build time and manages it using a data structure called stack.

  • A method in which we create or deallocate a block of memory during the execution of a program is known as dynamic memory allocation.The <stdlib. h> header file contains four methods that are utilised for this memory allocation in our system: malloc(), calloc(), realloc(), and free().

  • The difference between static and dynamic memory allocation in terms of efficiency is such that the static memory allocation is less efficient as compared to the dynamic memory allocation.

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