0x40Lesson 5 of 6

Write reusable functions

Pass values to functions and return results.

14 min 4-question quiz 1 code exercise

By the end of this lesson you can

Define and call a function that returns a value.

A function packages a reusable operation. Parameters name the inputs and declare their types; the return type appears after the parameter list. Go functions can return multiple values, a common pattern for returning a result together with an error.

main.go

1package main
2
3import "fmt"
4
5func double(value int) int {
6    return value * 2
7}
8
9func main() {
10    fmt.Println(double(6))
11}

Output

The caller receives the value after return. A function can also return (value, error) so callers can handle failure explicitly instead of relying on exceptions.

Key takeaways

Define and call a function that returns a value.
Go catches many mistakes while compiling.
Use small experiments to understand each new language feature.

Lesson quiz

4 questions · pass with 3 correct · up to 50 XP

Passing this quiz completes the lesson and keeps your streak going. Questions you miss come back in review sessions later.

Practice: write Go

Write Go in the editor and run it against sample input with a remote compiler. Your code is sent to Compiler Explorer to compile and run.

Exercise 1

Convert minutes to seconds

+25 XP

Write a function toSeconds that accepts minutes as an int and returns the number of seconds. Read a value and print the result.

Two minutes
Zero minutes

main.go

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Go is compiled and run by Compiler Explorer (godbolt.org), a free public service. Your source code and test input are sent to that service.

Questions about this lesson

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