How to check if a map is empty in Golang?

Question

When the following code:

if map == nil {     log.Fatal("map is empty") } 

is run, the log statement is not executed, while fmt.Println(map) indicates that the map is empty:

map[] 

Answer 1

You can use len:

if len(map) == 0 {     .... } 

From https://golang.org/ref/spec#Length_and_capacity

len(s) map[K]T map length (number of defined keys)

Answer 2

The following example demonstrates both the nil check and the length check that can be used for checking if a map is empty

package main  import (     "fmt" )  func main() {     a := new(map[int64]string)     if *a == nil {         fmt.Println("empty")     }     fmt.Println(len(*a)) } 

Prints

empty 0