Add and subtract
- Kotlin course
- Beginner
- Lesson 20/116
- 6 min
Add and test the addition and subtraction functions.
The add and subtract functions
The first two functions of the calculator are add and subtract. Both take two Ints and return an Int. add computes a + b; subtract computes a - b.
fun add(a: Int, b: Int): Int {
return a + b
}
fun subtract(a: Int, b: Int): Int {
return a - b
}You can call these from main as add(5, 3) and subtract(5, 3).
Practice Add add and subtract
Above the existing main, add fun add(a: Int, b: Int): Int { return a + b } and fun subtract(a: Int, b: Int): Int { return a - b }. Inside main, add println(add(5, 3)) and println(subtract(5, 3)); keep the existing println.
Starter code
fun main() {
println("Calculator")
}Sample solution
fun add(a: Int, b: Int): Int {
return a + b
}
fun subtract(a: Int, b: Int): Int {
return a - b
}
fun main() {
println("Calculator")
println(add(5, 3))
println(subtract(5, 3))
}Expected output
Calculator 8 2
When to use a function?
If you'll perform the same calculation in several places, it's good to move it into a function. In the calculator, add(5, 3) and add(10, 20) share code; this reduces errors and improves readability.
Functions also make testing easier by breaking code into pieces. Putting each operation in its own function simplifies debugging in the calculator.
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match the concepts
| Term | Meaning |
|---|---|
fun |
Function |
Int |
Integer |
return |
Return |
println |
Output |
2 What does `add(5, 3)` return?
- It throws an error
- 2
- 15
- 8 Correct answer
Explanation: The add function sums two numbers.
3 Complete the return statement
fun subtract(a: Int, b: Int): Int {
return a ____ b
}fun subtract(a: Int, b: Int): Int {
return a - b
}Explanation: subtract performs subtraction.