Subroutine: Definition, Explanation & Examples

Subroutine - an overview

A subroutine is a fundamental concept in programming that allows you to define a block of code that can be called multiple times. By using subroutines, programmers can modularise the code, improving maintenance and readability. In this article, we will explore how subroutines work, explain their benefits and give some examples of their use.

What is a subroutine?

A subroutine, also known as a function or procedure, is a named block of code that performs a specific task. Subroutines can accept parameters, use them in the code and return data. By using subroutines, developers can avoid repetitive pieces of code, which increases the efficiency of the code.

Types of subroutines

• Functions: These usually return a value and can be used in expressions.
• Procedures: These perform an action but do not return a value.

Advantages of using subroutines

The use of subroutines offers numerous advantages:

1. Modularity: subroutines help to organise the code into smaller, manageable parts.
2. Reusability: Once defined, subroutines can be used again and again in different programmes or components.
3. Easier maintenance: Changes can easily be made to a subroutine without affecting the entire code.
4. Improved readability: Well-named subroutines make the code easier to understand.

How to create subroutines

The way a subroutine is created varies depending on the programming language, but the basic elements remain the same. Here is a simple example in Python:

def calculate_sum(a, b): return a + b

In this example, calculate_sum is a subroutine that accepts two parameters a and b and returns their sum.

Subroutines in different programming languages

Subroutines are implemented differently in many programming languages. Here are some examples:

• Java: In Java, subroutines are defined as methods.
• C: In C, subroutines are referred to as functions.
• JavaScript: Subroutines are implemented as functions and can even be used as callback functions.

Illustrative example on the topic: Subroutine

Imagine you live in an exciting city and run a small café. Every day you have to prepare the drinks: Coffee, tea and lemonade. Instead of writing down the recipe over and over again, you decide to create a notepad for each drink. Every time a customer places an order, you simply refer to the corresponding note.

In programming, it works similarly with subroutines. Once you have the recipe for preparing a particular drink in the form of a subroutine, you can call it up several times without having to rewrite it each time. This makes working much more efficient!

Conclusion

Subroutines are an essential part of programming and are a great way to organise code and use it effectively. They contribute to the modularity, reusability and maintainability of software. If you would like to learn more about related concepts, take a look at our articles on algorithms and variables.