Conditional Statements: if and when

Conditional statements allow you to control the flow of your Kotlin programs by making decisions based on certain conditions. The two main conditional statements in Kotlin are if and when. Both help you execute different blocks of code depending on the values of variables or the results of expressions.

The if statement is used to check a condition and execute code only if that condition is true. It can also include else and else if branches to handle alternative cases.

The when statement is Kotlin's more flexible version of the traditional switch statement found in other languages. It allows you to match a value against a series of conditions and execute code based on the first matching branch. This can make your code cleaner and easier to read when you have multiple possible conditions to check.

Below, you will find a Kotlin example that demonstrates both if and when statements in action.

In the code above, you first see an if statement that checks the value of the temperature variable. If the temperature is greater than 25, the program prints "It's hot outside." If the temperature is between 16 and 25 (inclusive), it prints "The weather is moderate." Otherwise, it prints "It's cold outside." This demonstrates how if, else if, and else branches work together to handle multiple conditions.

Next, the when statement assigns a value to the weatherDescription variable based on the range in which the temperature falls. If the temperature is between 26 and 40, weatherDescription becomes "Sunny and warm". If it is between 16 and 25, it becomes "Pleasant", and if it is between 0 and 15, it becomes "Chilly". The else branch covers any other values, assigning "Extreme weather".

The main difference between if and when is in their usage: use if for simple true/false decisions or a small number of conditions, and use when for checking a value against several possibilities, which makes your code more readable and maintainable when dealing with multiple cases.