LearnViz CompSci
Home / Learn / Programming Fundamentals / Parameters and Arguments

Beginner Topic 13 of 54 Programming Fundamentals

Parameters and Arguments

Placeholders in a function definition versus actual values passed in a call.

How it works

Parameters are the names declared in a function definition, while arguments are the actual values supplied at call time. Languages offer positional parameters, keyword arguments, default values and variadic parameters that collect any number of extra values. How arguments are bound, by value or by reference, determines whether the function can alter the caller's data.

Step-by-step walkthrough

  1. Parameters a and b are placeholders in the definition.
  2. Arguments 2 and 3 are the actual values at the call site.
  3. On the call each argument is bound to the matching parameter by position.
  4. The body runs using those bound values.
  5. Extra or missing arguments cause an error unless defaults exist.

Where it is used

Configuring behavior, for example connect(host, port=5432, timeout=10), passing data into computations and designing flexible APIs with optional settings all rely on parameters. Keyword arguments make calls self-documenting.

Common pitfall

Mutable default arguments, such as an empty list in Python, are created once and shared between calls, causing famous bugs. Too many parameters or swapped positional arguments of the same type lead to errors; group related values in an object or use keyword arguments.

Where it fits in the course

Parameters and Arguments is topic 13 of 54 in Programming Fundamentals, rated Beginner. It follows Functions. The next topic is Return Values.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Programming Fundamentals quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is Parameters and Arguments?
Placeholders in a function definition versus actual values passed in a call. It belongs to Programming Fundamentals and is a beginner-level topic.
Where do people use Parameters and Arguments?
Configuring behavior, for example connect(host, port=5432, timeout=10), passing data into computations and designing flexible APIs with optional settings all rely on parameters.
What is the most common mistake with Parameters and Arguments?
Mutable default arguments, such as an empty list in Python, are created once and shared between calls, causing famous bugs.
What should I learn before this topic?
Start with Functions, the topic just before it in Programming Fundamentals.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Programming Fundamentals quiz.
Is Parameters and Arguments hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn Parameters and Arguments?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Parameters and Arguments?
Functions, Return Values, While Loops are closely connected. The full list is in the related topics section of this page.
What should I study after Parameters and Arguments?
Continue with Return Values, the next topic in Programming Fundamentals.

Related topics