C# Fundamentals · Variables & Data Types · Lesson 5 of 22
The var Keyword
Concept
The var Keyword
var lets the compiler infer a variable's type from its initial value, while still keeping the type fixed and checked at compile time.
By the end of this lesson
- Explain the core idea behind The var Keyword.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
ExampleRunnable
var name = "Alex"; // inferred as string
var age = 20; // inferred as intSelf-check before continuing
Without looking at the example, describe what changes when you modify one input in The var Keyword. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Declare two variables with var and explain what type each was inferred as.
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