Pseudocode

Pseudocode is a clear, compact, unambiguous description of an algorithm or computer program aimed to communicate this to other people. It is more structured and precise than English, but more high-level than code, with a focus on readability.

Writing pseudocode

Before presenting the algorithm, make sure the reader understands the aim of the program, e.g. give a concise description of expected input and output. Then aim to follow these principles:

• Follow guidelines for good code (e.g. following variable naming conventions, refrain from using break/goto)
• Use proper English
• Use simple non-technical terms where possible: use the vocabulary of the application domain. For example, use "Extract the next word from the line" instead of "Set word to get next token"
• Make sure that your pseudocode can be understood to mean exactly one thing

Basic constructs

• Express each statement or action on its own line.
• Include programming constructs that are common in most (imperative) programming languages whenever applicable (for, while, repeat/until, switch/case, return, if/then/else, etc.).
• Use indentation of the inner parts of loops, if statements, and methods/function bodies (this is preferred over begin/end for conciseness).
• Let keywords and commands stand out clearly (e.g. using bold face).
• Use comments, indicated using a clear symbol and layout (e.g. // and position to the right of the code).
• For assignments (e.g., of 42 to x) you may use either x←42 or x:=42. These are preferred over x=42, because this can then be reserved for the logical statement of whether x is equal to 42.
• Refrain from using language-specific constructs such as using a dot for a method call to an object (as in this.example()).
• When methods are using parameters, assume they are passed on by value (i.e., a copy is assumed to be made).

Generally, aim to be concise. So include essential details such as the initialisation of variables and return and/or print statements, but leave out unnecessary or obvious details, such as type declarations if this is clear from the context, the implementation of data structures (unless you are explaining the inner workings of a data structure), and a sorting routine (unless you are explaining the inner workings of it).

Advanced constructs