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Pseudocode: Definition, Conventions, and Example

Pseudocode example with indented steps, variables, loops, and conditions

Written by

Amber Colvin

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Pseudocode is a language-neutral way to describe an algorithm. It uses familiar words, named variables, and indentation to show what a program should do without requiring the exact syntax of Python, JavaScript, Java, or another language.

A clear pseudocode plan helps you check the logic, explain it to other people, and translate it into executable code later. It focuses on actions and decisions rather than punctuation or language-specific rules.

What Is Pseudocode, and What Is It Used For?

Pseudocode is used to plan an algorithm before implementation. An algorithm is a defined sequence of steps for completing a task, such as calculating an average, searching a list, or processing a user’s input.

Writing pseudocode first makes the logic easier to review. You can identify missing inputs, incorrect conditions, or endless loops before dealing with the details of a programming language. It is also useful for documentation because a reader can understand the process without knowing the language used to build it.

Effective pseudocode should:

  • State the steps in the order they happen.
  • Name the data the algorithm reads, stores, and produces.
  • Show decisions and repeated actions explicitly.
  • Use consistent indentation and control-flow terms.

Which Conventions Make Pseudocode Readable for Sequence, Input, Output, Conditions, and Loops?

There is no single universal pseudocode standard. Choose clear terms and apply them consistently. These conventions cover most algorithms:

  • Sequence: Put one action after another, with each step on its own line. The order of the lines represents the order of execution.
  • Input: Use INPUT to show that the algorithm receives data, such as INPUT customer_name.
  • Output: Use OUTPUT to show displayed or returned information, such as OUTPUT total.
  • Assignment: Use SET to give a variable a value, such as SET total TO 0. Some authors use an equals sign instead.
  • Condition: Use IF, THEN, ELSE, and END IF to describe a decision. Indent the actions belonging to each branch.
  • Loop: Use FOR for a known number of repetitions and WHILE when repetition continues as long as a condition remains true. Mark the loop’s boundary with END FOR or END WHILE.

Use descriptive variable names, such as average_price rather than x. Capitalized keywords can make control flow easy to scan, but capitalization is optional. The important rule is consistency.

How Does Pseudo Code Differ From Executable Code and Flowcharts?

Pseudocode is not executable code. A compiler or interpreter cannot run it because terms such as INPUT and END IF do not have one fixed technical meaning. Real code must follow the grammar, data types, operators, and libraries of a chosen programming language.

A flowchart represents an algorithm visually with symbols, arrows, and branches. Pseudocode represents the same logic as structured text. Flowcharts can make paths and decisions immediately visible, while pseudocode is usually faster to edit, search, and convert into code. Neither format replaces careful testing.

How to write pseudocode: A Worked Example With Variables, Indentation, and Program-Code Translation

Suppose an algorithm must read the prices of three items, calculate the total and average, and report whether the average is above 50. The following example uses sequence, input, output, a loop, a condition, and named variables:

  • START
  • SET item_count TO 3
  • SET total TO 0
  • FOR item_number FROM 1 TO item_count
    • INPUT price
    • SET total TO total + price
  • END FOR
  • SET average_price TO total / item_count
  • IF average_price > 50 THEN
    • OUTPUT “The average price is high.”
  • ELSE
    • OUTPUT “The average price is within budget.”
  • END IF
  • OUTPUT total, average_price
  • END

To translate this into program code, map each abstract action to the target language’s syntax. For example, a Python implementation could use total = 0 for assignment, float(input()) for numeric input, for item_number in range(1, item_count + 1) for the counted loop, and if average_price > 50: for the condition. The indentation and variable relationships remain the same, but the keywords and punctuation now follow Python’s rules.

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