Chapter 2 · Lesson 1

Data Types in Go

Go is statically typed with a simple type system.

Basic Types:

bool: true or false
string: UTF-8 encoded text
int, int8, int16, int32, int64
uint, uint8, uint16, uint32, uint64
float32, float64
complex64, complex128
byte (alias for uint8)
rune (alias for int32, represents Unicode)

Variable Declaration:

var name type = value
var name = value (type inferred)
name := value (short declaration, inside functions only)

Zero Values: Uninitialized variables have zero values:

Numbers: 0
Booleans: false
Strings: ""
Pointers/slices/maps: nil

Code Examples

Go Data Typesgo

package main

import "fmt"

func main() {
    // Variable declaration styles
    var explicit string = "Hello"
    var inferred = "World"
    short := "Go"
    
    fmt.Println(explicit, inferred, short)
    
    // Numeric types
    var i int = 42
    var f float64 = 3.14
    var b bool = true
    
    fmt.Printf("int: %d, float: %.2f, bool: %t\n", i, f, b)
    
    // Zero values
    var (
        defaultInt    int
        defaultFloat  float64
        defaultString string
        defaultBool   bool
    )
    
    fmt.Printf("Zero values: %d, %f, %q, %t\n", 
        defaultInt, defaultFloat, defaultString, defaultBool)
    
    // Constants
    const Pi = 3.14159
    const (
        StatusOK    = 200
        StatusError = 500
    )
    
    fmt.Println("Pi:", Pi)
    
    // Type conversion (explicit only)
    var x int = 42
    var y float64 = float64(x)
    var z int = int(y)
    
    fmt.Printf("Conversions: %d -> %.2f -> %d\n", x, y, z)
    
    // Strings and runes
    s := "Hello, 世界"
    fmt.Printf("String: %s, Length: %d, Runes: %d\n", 
        s, len(s), len([]rune(s)))
}

Go requires explicit type conversion - there's no implicit casting. Zero values make uninitialized variables safe.

Quick Quiz

1. What is the zero value for a string in Go?

Was this lesson helpful?

Code Examples

Go Data Typesgo

package main

import "fmt"

func main() {
    // Variable declaration styles
    var explicit string = "Hello"
    var inferred = "World"
    short := "Go"
    
    fmt.Println(explicit, inferred, short)
    
    // Numeric types
    var i int = 42
    var f float64 = 3.14
    var b bool = true
    
    fmt.Printf("int: %d, float: %.2f, bool: %t\n", i, f, b)
    
    // Zero values
    var (
        defaultInt    int
        defaultFloat  float64
        defaultString string
        defaultBool   bool
    )
    
    fmt.Printf("Zero values: %d, %f, %q, %t\n", 
        defaultInt, defaultFloat, defaultString, defaultBool)
    
    // Constants
    const Pi = 3.14159
    const (
        StatusOK    = 200
        StatusError = 500
    )
    
    fmt.Println("Pi:", Pi)
    
    // Type conversion (explicit only)
    var x int = 42
    var y float64 = float64(x)
    var z int = int(y)
    
    fmt.Printf("Conversions: %d -> %.2f -> %d\n", x, y, z)
    
    // Strings and runes
    s := "Hello, 世界"
    fmt.Printf("String: %s, Length: %d, Runes: %d\n", 
        s, len(s), len([]rune(s)))
}

Go requires explicit type conversion - there's no implicit casting. Zero values make uninitialized variables safe.