Pseudocode describes the individual steps of an algorithm using simple, readable language that’s easy to grasp for anyone with basic programming knowledge. Here’s how to write your own.
Along the way from the idea to a ready solution, data scientists and developers face several stages. It includes algorithm design and validation, applying the algorithm to actual issues, and verifying its performance on various input datasets.
When approaching a new problem, it’s a good idea to put aside the constraints of programming language syntax. Pseudocode enables you to do that very thing, devoting your attention rather to the algorithm’s structure and logic without considering particular language constraints. Clarity can be a blessing to work with when considering the efficacy of an algorithm.
What Is Pseudocode?
From programming areas such as app development, web development, and data science, pseudocode is a handy utility. It is useful in expressing the logic of an algorithm in simple, syntax-less language, which is simple to follow. While it isn’t written in a formal language, pseudocode should clearly reflect the algorithm’s structure so that converting it into actual code becomes a straightforward translation into a programming language of choice.
The Main Constructs of Pseudocode
At its foundation, pseudocode relies on six primary programming constructs always written in uppercase: SEQUENCE, CASE, WHILE, REPEAT-UNTIL, FOR, and IF-THEN-ELSE. These constructs define the flow of the algorithm and are often referred to as keywords.
- SEQUENCE – Executes tasks one after another in a linear order.
- WHILE – A loop that continues as long as a specified condition holds true, with the condition checked at the start.
- REPEAT-UNTIL – A looping structure where the condition is evaluated after the loop body has run.
- FOR – Another common looping mechanism, typically used for iterating a set number of times.
- IF-THEN-ELSE – A conditional control that allows different actions based on whether a condition is met.
- CASE – A broader form of IF-THEN-ELSE, used for multiple condition branches.
These six constructs cover the majority of algorithmic needs, but depending on the complexity of your application, additional commands may be necessary. Two commonly used additions include:
CALL – Used to invoke classes or functions.
EXCEPTION, WHEN – Used to handle errors or exceptions during execution.
Depending on your domain, you might introduce additional constructs. Just ensure these keywords are never repurposed as variable names and are widely understood within your team or organization.
How to Write Pseudocode
Everyone tends to develop their own style of writing pseudocode because it’s meant for human interpretation, not machines. That said, while pseudocode is less strict than actual programming languages, following some basic guidelines can ensure clarity and consistency.
Write Pseudocode-
- Start every line with a capitalized keyword, often from the core constructs.
- Keep each line limited to a single statement.
- Use indentation to represent structure and nested logic.
- Conclude multi-line blocks with the appropriate END keyword (like ENDIF, ENDWHILE).
- Avoid using syntax specific to any programming language.
- Base your naming on the domain or problem context, not technical implementation. For example: “Append the last name to the first name” rather than “name = first+last.”
- Keep your writing concise, clear, and easy to follow.
Pseudocode Example
By applying these rules, your pseudocode will be easier to understand and maintain. Consider this scenario: a company is creating a 10-question multiple-choice quiz on workplace safety. Employees who answer at least eight questions correctly pass and get a certificate; others must retake the quiz. Here’s how the pseudocode might look:
IF employee answers eight or more questions correctly
- Display message: “Congratulations on passing the quiz!”
- Redirect to certificate download page
ELSE
- Display message: “Let’s try again!”
- Return to the beginning of the quiz
If you’ve studied computer science, attended a coding bootcamp, or taken a programming course, you’ve likely encountered pseudocode. Initially, many learners question its usefulness, thinking, “Why write it twice?” While that may hold true for basic problems, as your projects grow in scale and complexity, the benefits of pseudocode become clear. It allows you to spot logical flaws early and prevents time-consuming debugging later in the development process.
Why Use Pseudocode?
Pseudocode Is Easier to Read
- Programmers usually work with people who are not technical like business executives, project managers, or mathematicians. Pseudocode fills the gap by making the logic easily understandable to everyone.
Pseudocode Simplifies Code Construction
- Creating pseudocode helps outline the algorithm, making it easier to convert into functional code in any programming language. It acts as a roadmap for development.
Pseudocode Is a Good Middle Point Between Flowchart and Code
- Jumping straight from a conceptual flowchart to code can be bumpy. Pseudocode offers a smoother transition, serving as an intermediary planning step.
Pseudocode Is a Helpful Starting Point for Documentation
- Writing documentation can be daunting, especially at the beginning. Pseudocode provides a solid starting reference and can even be added as a docstring at the top of a code file to explain the logic.
Pseudocode Allows for Quick Bug Detection
- Since it’s written in plain language, pseudocode is easier to modify and troubleshoot. Identifying logical errors here is often quicker than debugging actual code.
Pseudocode is still an underappreciated asset in programming. However, when it is written well and coherently, it can greatly simplify the process of development, from conception to implementation, making your transition from idea to reality that much smoother.
Frequently Asked Questions
What is pseudocode?
Pseudocode is a simplified, human-readable outline of a program’s logic used to illustrate how an algorithm works, without writing actual code. It serves as a conceptual draft, allowing programmers of all levels to easily understand the algorithm’s structure and flow.
How do you write a pseudocode?
When writing pseudocode, consider the following general practices:
- Limit each line to a single action or statement
- Begin each line with a capitalized keyword (usually a control structure)
- Use indentation to show logical nesting and structure
- Use terminology based on the problem domain rather than the code implementation
- Write in a clear, simple, and language-agnostic style
However, writing pseudocode isn’t bound by strict rules, so individual styles may vary among developers.
What is an example of pseudocode?
Take the example of an eCommerce store offering discounts for orders of $50 or more. Based on best pseudocode practices, here’s how the logic might look:
IF order amount is $50 or more
- Apply discount
- Display message: “Discount has been applied!”
ELSE
- Do not apply discount
- Display message: “Add more items to cart for discount!”
Is pseudocode easy to learn?
Yes, pseudocode is designed to be simple. Since it relies on plain language rather than strict programming syntax, anyone with a basic grasp of programming can quickly learn to write and understand it.
What is the difference between pseudocode and code?
While both serve to outline an algorithm, pseudocode is written in plain language without adhering to any specific programming language’s syntax. Actual code, on the other hand, includes precise syntax and structures that machines can interpret. Pseudocode is a planning tool, whereas code is the implementation that gets executed.
