🎓 A1Learner
🔍

Go Booleans

A boolean is a value that is either true or false. A comparison of two values makes a boolean.

A bool value prints

A bool variable holds true here. Printing the variable shows the word true.

package main

import "fmt"

func main() {
	ready := true
	fmt.Println(ready)
}

Three comparisons

Each comparison makes a bool from two numbers. The prints show true first, then false twice.

package main

import "fmt"

func main() {
	fmt.Println(7 >= 7)
	fmt.Println(3 <= 2)
	fmt.Println(5 != 5)
}

Text compares by value

The == sign compares two strings by their text. Both sides hold the same text, so the result is true.

package main

import "fmt"

func main() {
	fmt.Println("go" == "go")
}

Joining and flipping

&& needs both sides true, so the first print gives false. || needs one side true, and ! flips true to false.

package main

import "fmt"

func main() {
	fmt.Println(true && false)
	fmt.Println(false || true)
	fmt.Println(!true)
}

Example

package main

import "fmt"

func main() {
	age := 20
	member := false
	fmt.Println("Adult:", age >= 18)
	fmt.Println("Member price:", age >= 18 && member)
}

Key points

  • The bool type holds true or false.
  • Use == to test whether two values are equal.
  • Use != to test whether two values differ.
  • The sign >= tests greater than or equal, and <= tests less than or equal.
  • && needs both sides true, and || needs one side true.
  • ! flips a boolean, turning true into false and false into true.

In this example, age holds 20 and member holds false. The test age >= 18 gives true, so the first line prints Adult: true. The joined test also needs member, so the second line prints Member price: false.

Note

A comparison makes its bool at once. A program can print the bool or store it in a variable.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Go Playground

Exercise

What does 5 != 5 print?