4-variables

Variables

The var statement declares a list of variables; as in function argument lists, the type is last.

A var statement can be at package or function level. We see both in this example.

package main

import "fmt"

var c, python, java bool

func main() {
	var i int
	fmt.Println(i, c, python, java)
}

Variables with initializers

A var declaration can include initializers, one per variable.

If an initializer is present, the type can be omitted; the variable will take the type of the initializer.

package main

import "fmt"

var i, j int = 1, 2

func main() {
	var c, python, java = true, false, "no!"
	fmt.Println(i, j, c, python, java)
}

Short variable declarations

Inside a function, the := short assignment statement can be used in place of a var declaration with implicit type.

Outside a function, every statement begins with a keyword (var, func, and so on) and so the := construct is not available.

package main

import "fmt"

func main() {
	var i, j int = 1, 2
	k := 3
	c, python, java := true, false, "no!"

	fmt.Println(i, j, k, c, python, java)
}

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)
}

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