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What is modular programming?

The concept of modular programming originated in the 1960s to help users. Programmers began to divide the more extensive programs into smaller parts. Though the concept of modular programming is six decades old, it is the most convenient programming method.

What is modular programming?


Modular programming is defined as a software design technique that focuses on separating the program functionality into independent, interchangeable methods/modules. Each of them contains everything needed to execute only one aspect of functionality.

Talking of modularity in terms of files and repositories, modularity can be on different levels -

  • Libraries in projects
  • Function in the files
  • Files in the libraries or repositories

Modularity is all about making blocks, and each block is made with the help of other blocks. Every block in itself is solid and testable and can be stacked together to create an entire application. Therefore, thinking about the concept of modularity is also like building the whole architecture of the application.

Examples of modular programming languages - All the object-oriented programming languages like C++, Java, etc., are modular programming languages.


A module is defined as a part of a software program that contains one or more routines. When we merge one or more modules, it makes up a program. Whenever a product is built on an enterprise level, it is a built-in module, and each module performs different operations and business. Modules are implemented in the program through interfaces. The introduction of modularity allowed programmers to reuse prewritten code with new applications. Modules are created and merged with compilers, in which each module performs a business or routine operation within the program.

For example - SAP(System, Applications, and Products) comprises large modules like finance, payroll, supply chain, etc. In terms of softwares example of a module is Microsoft Word which uses Microsoft paint to help users create drawings and paintings.

Advantages of modular programming

The following are advantages of modular programming -

  • Code is easier to read - Working on modular programming makes code easier to read because functions perform different tasks as compared to monolithic codes. Sometimes modular programming can be a bit messy if we pass arguments and variables in different functions. The use of modules should be done in a sensible manner so as to avoid any problem. Functions should be neat, clean, and descriptive.
  • Code is easier to test - In software, some functions perform fewer tasks and also functions that perform numerous tasks. If the software is easily split using modules, it becomes easier to test. We can also focus on the riskier functions during testing and need more test cases to make it bug-free.
  • Reusability - There are times where a piece of code is implemented everywhere in our program. Instead of copying and pasting it, again and again, modularity gives us the advantage of reusability so that we can pull our code from anywhere using interfaces or libraries. The concept of reusability also reduces the size of our program.
  • Faster fixes - Suppose there is an error in the payment options in any application, and the bug needs to be removed. Modularity can be a great help because we know that there will be a separate function that will contain the code of payments, and only that function will only be rectified. Thus using modules to find and fixing bugs becomes much more smooth and maintainable.
  • Low-risk update - In modular programming, a defined layer of APIs protects things that use it from making changes inside the library. Unless there is a change in the API, there is a low risk for someone's code-breaking. For example, if you didn't have explicit APIs and someone changed a function they thought was only used within that same library (but it was used elsewhere), they could accidentally break something.
  • Easy collaboration - Different developers work on a single piece of code in the team. There are chances of conflicts when there's a git merge. This conflict can be reduced if the code is split between more functions, files, repos, etc. We can also provide ownership to specific code modules, where a team member can break them down into smaller tasks.

Disadvantages of modular programming

The following are disadvantages of modular programming -

  • There is a need for extra time and budget for a product in modular programming.
  • It is a challenging task to combine all the modules.
  • Careful documentation is required so that other program modules are not affected.
  • Some modules may partly repeat the task performed by other modules. Hence, Modular programs need more memory space and extra time for execution.
  • Integrating various modules into a single program may not be a task because different people working on the design of different modules may not have the same style.
  • It reduces the program's efficiency because testing and debugging are time-consuming, where each function contains a thousand lines of code.

Modular programming is an ancient concept, but it is still a buzzword among developers. For a developer, one must learn to code in modules. There are times when we need to retrieve any code, make a dummy module for testing, and minimize the risk factors. Modular programming is bagged with such features making it essential.

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