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Learning how to write pseudocode is a skill that comes in handy not just when you’re a beginner but also when you’re:
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In this article, we’ll discuss:
Before delving into the details of how to write pseudocode, it is worth looking at the definition of pseudocode to understand what pseudocode really means. Pseudocode refers to a high-level implementation of an algorithm that serves as mock code.
Here, by “high-level implementation,” we mean that while pseudocode has the structure and logic of a source code, the algorithm implementation is written closer to plain English. Pseudocode is not a programming language, is farther from machine language, and cannot be run directly. Here’s what it does:
To implement and run an algorithm, we first convert it into pseudocode, which is not programming-language-specific but represents the algorithm’s logic in its entirety. It can then be converted into actual code in any language and run.
In essence, an algorithm shows what logic needs to be implemented; pseudocode shows how the algorithm should be implemented. The code implements what needs to be implemented (algorithm) as per the pseudocode structure.
Pseudocode describes how an algorithm should be structured to work. It serves many purposes and can be useful to you, those who work with you, and those who come after you in several ways:
There are three basic elements of pseudocode:
Here’s the pseudocode for multiplying two numbers:
NUMBER number1, number2, product
OUTPUT("Input number 1:")
OUTPUT("Input number 2:")
While this may be a strange way to begin instructions to write pseudocode, it needs to be said — there are no broad standards for pseudocode syntax. Pseudocode is subjective and non-standard, and therefore, there aren’t absolute rules.
That said, your university or company may have its own preferred (limited) set of standards. Some preferences are often held widely enough since they come with many benefits.
It’s also important that other programmers reading the pseudocode should be able to understand whatever rules you use easily. What’s most important in a coding project you’re handling alone is that your pseudocode should help you:
With that out of the way, let us dive right into some guidelines you can follow to write professional-looking, readable pseudocode:
If you’re an experienced developer solving complicated problems involving multiple edge cases, data structures, algorithms, or loops, writing pseudocode will give you the clarity you need to implement the solution while handling all edge cases accurately.
Suppose you’re working on a group programming project. In that case, all members writing pseudocode for the parts they’re handling will make it easier for all other members to stay on the same page and understand the coder’s intent and solution.
If you’re working for a company, adding pseudocode as comments will serve as documentation. It will keep helping newcomers, and the software engineers tasked with maintaining your code long after you move on from that role.
Given below are the pseudocode templates for the most commonly used statements while writing pseudocode:
IF condition THEN
FOR Loop Pseudocode:
FOR iteration bounds
WHILE Loop Pseudocode:
CASE expression OF
condition 1: sequence 1
condition 2: sequence 2
condition n: sequence n
Let us now see what pseudocode for a problem would look like by taking a simple example problem statement:
Write code to print numbers from 1 to 100. The catch is:
FOR j <-- 1 TO 100 DO
IF j is divisible by 3 AND j is divisible by 5 THEN
ELSE IF j is divisible by 5 THEN
ELSE IF j is divisible by 3 THEN
1. Is pseudocode useful only for beginners?
No. Pseudocode is for anyone who wants to communicate the intent and logic of their code easily and effectively to anyone reading it later. The person benefitting could be the programmer — when used before implementing a complex algorithm and when the coder revisits the code after some months of its implementation. The person benefitting could also be colleagues, teammates, and juniors who might need to understand the code to do their job well.
2. What is the difference between pseudocode and flowchart?
The main difference between pseudocode and flowchart is that flowchart is a pictorial representation of the solution model to a problem. In contrast, pseudocode is not pictorial but a high-level representation of the operating principles of an algorithm.
3. What is the difference between pseudocode and source code?
The main difference between pseudocode and source code is that source code is written in a particular computer language and is executable in that language. In contrast, pseudocode is not executable and does not belong to any particular computer language.
4. What is the difference between Algorithm, Pseudocode, and Program?
An algorithm is a specific, defined sequence of steps that need to be followed in order to solve a given problem. Pseudocode is a high-level representation of an algorithm written in no particular programming language which is also not executable. Executable code written in a specific programming language is called a program.
5. What are some alternatives to Pseudocode?
Some alternatives to Pseudocode are Flowcharts, Drakon charts, and Unified Modified Language charts or UML charts.
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