Lesson 6 / 25

if and when

Explain if and when, run a focused example, and inspect the result.

The essential idea

if and when makes a Kotlin program more expressive while keeping the code readable. Identify the value, the rule, and the result before you try to remember the syntax.

See the Kotlin path

This topic is one clear step from source code to useful output.

Kotlin source code passing through compiler to output.
Figure 3.1 — Keep the program path visible.

A practical habit

For if and when, run a very small example and change only one part. The compiler and output will show whether your explanation is correct.

Quick check

Quick check: How should you practise if and when?

  • Run a focused small program.
  • Memorize without compiling.
  • Ignore errors.
Answer

Run a focused small program. — Small experiments make cause and effect visible.