Programming

Basic types

Go’s basic types are

• bool
• string
• int int8 int16 int32 int64
• uint uint8 uint16 uint32 uint64 uintptr
• byte // alias for uint8
• rune // alias for int32, represents a Unicode code point
• float32 float64
• complex64 complex128

The example shows variables of several types, and also that variable declarations may be “factored” into blocks, as with import statements.

The int, uint, and uintptr types are usually 32 bits wide on 32-bit systems and 64 bits wide on 64-bit systems. When you need an integer value you should use int unless you have a specific reason to use a sized or unsigned integer type.

package main

import (
  "fmt"
  "math/cmplx"
)

var (
  ToBe   bool       = false
  MaxInt uint64     = 1<<64 - 1
  z      complex128 = cmplx.Sqrt(-5 + 12i)
)

func main() {
  fmt.Printf("Type: %T Value: %v\n", ToBe, ToBe)
  fmt.Printf("Type: %T Value: %v\n", MaxInt, MaxInt)
  fmt.Printf("Type: %T Value: %v\n", z, z)
}

Zero values

Variables declared without an explicit initial value are given their zero value.

The zero value is:

• 0 for numeric types,
• false for the boolean type, and
• ”” (the empty string) for strings.

package main

import "fmt"

func main() {
  var i int
  var f float64
  var b bool
  var s string
    fmt.Printf("%v %v %v %q\n", i, f, b, s)
  }