Zero value

Zero value of a variable in Golang refers to the value it contains till it is not explicitly initialized. Zero value may also be referred as default value of a variable.
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This zero value is different for a variable of different data types.
Example, for a variable of bool type, the zero value is false; for integers, it is 0 etc. Thus, below code will print 0.

package main

import "fmt"

func main(){
   var int num
   fmt.Println(num)
}

Zero value only exists till the variable is not provided a value. Also, below code snippets are equivalent.

var num int
var num int = 0

var flag bool
var flag bool = false

var name string
var name string = ""

Below table provides a quick reference to the zero value for each data type.

An uninitialized array will contain all the elements with the zero value of the type of array. Example,

var arr[5] int
fmt.Print(arr)

will print [0,0,0,0,0] since the zero value of int(which is the data type of array) is 0.