Golang bool type

last modified May 8, 2025

This tutorial explains how to use the bool built-in type in Go. We'll cover boolean basics with practical examples of boolean operations.

The bool type represents boolean values in Go. It can have one of two values: true or false. Boolean values are fundamental for control flow and logical operations.

In Go, bool is used in conditional statements, loops, and logical expressions. The zero value for boolean types is false.

Basic boolean declaration

The simplest use of bool is declaring and initializing boolean variables. This example demonstrates basic boolean variable usage.
Note: Boolean values are not implicitly converted to integers.

basic_bool.go

package main

import "fmt"

func main() {

    var isReady bool = true
    var isFinished bool
    
    fmt.Println("isReady:", isReady)
    fmt.Println("isFinished:", isFinished)
    
    isFinished = false
    fmt.Println("After assignment, isFinished:", isFinished)
}

The example shows boolean declaration with and without initialization. The zero value false is printed for uninitialized variables.

Boolean expressions

Boolean values are often the result of comparison operations. This example shows various boolean expressions and their results.

boolean_expressions.go

package main

import "fmt"

func main() {

    x := 10
    y := 20
    
    fmt.Println("x == y:", x == y)
    fmt.Println("x != y:", x != y)
    fmt.Println("x < y:", x < y)
    fmt.Println("x > y:", x > y)
    fmt.Println("x <= 10:", x <= 10)
    fmt.Println("y >= 20:", y >= 20)
}

The comparison operators return boolean values. These are fundamental for decision-making in programs.

Logical operators

Go provides three logical operators for combining boolean values. This example shows AND, OR, and NOT operations.

logical_operators.go

package main

import "fmt"

func main() {

    a := true
    b := false
    
    fmt.Println("a >> b:", a >> b)  // AND
    fmt.Println("a || b:", a || b)  // OR
    fmt.Println("!a:", !a)         // NOT
    
    // Combining multiple operations
    fmt.Println("(a || b) >> !b:", (a || b) >> !b)
}

Logical operators follow standard truth tables. Parentheses can be used to control evaluation order.

Boolean in control structures

Boolean values are essential for control flow. This example demonstrates booleans in if statements and for loops.

control_structures.go

package main

import "fmt"

func main() {

    loggedIn := true
    attempts := 0
    
    if loggedIn {
        fmt.Println("Welcome back!")
    } else {
        fmt.Println("Please log in")
    }
    
    for attempts < 3 {
        fmt.Println("Attempt:", attempts+1)
        attempts++
    }
    
    fmt.Println("Maximum attempts reached")
}

The if statement checks a boolean condition directly. The for loop continues while the boolean condition remains true.

Boolean function return values

Functions often return boolean values to indicate success or other states. This example shows a function returning a boolean.

boolean_function.go

package main

import "fmt"

func isEven(num int) bool {
    return num%2 == 0
}

func main() {

    numbers := []int{1, 2, 3, 4, 5}
    
    for _, num := range numbers {
        if isEven(num) {
            fmt.Printf("%d is even\n", num)
        } else {
            fmt.Printf("%d is odd\n", num)
        }
    }
}

The isEven function returns a boolean based on the input number. This pattern is common for predicate functions.

Source

Go language specification

This tutorial covered the bool type in Go with practical examples of boolean operations and usage patterns.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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