Zero Values in Go

You can declare a variable without giving it a starting value. Go does not leave it with an unknown value; it initializes the variable to the zero value for its type. This lets you use the variable immediately. in The Golang Official Documentation

package main
 
import "fmt"
 
func main() {
	var count int
	var fraction float64
	var ready bool
	var name string
 
	fmt.Printf("%d %.1f %t %q\n", count, fraction, ready, name)
}

If you’ll run this with go run main.go, you’ll get 0 0.0 false ""
In the example, the int and float64 variables start at zero, ready starts at false, and name starts as an empty string. %q puts quotes around the string in the output, making that empty value visible as "".

The same rule applies inside arrays. If you declare an array of bytes without an initializer, every element begins at 0; you do not have to fill it with zeros yourself.