#####   ######  #####    ###    #   #  ###  #   #  ######
##  ##  ##      ##  ##  ## ##   #   #   #   #   #  ##
#####   ####    #####   #   #   #   #   #   #   #  ####
##  #   ##      ##      ## ##    # #    #    # #   ##
##   #  ######  ##       ###      #    ###    #    ######

$ curl repovive.com/roadmaps/go/maps/nil-maps

░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░█████████████████████████████████████████████

#####   ######  #####    ###    #   #  ###  #   #  ######
##  ##  ##      ##  ##  ## ##   #   #   #   #   #  ##
#####   ####    #####   #   #   #   #   #   #   #  ####
##  #   ##      ##      ## ##    # #    #    # #   ##
##   #  ######  ##       ###      #    ###    #    ######

$ curl repovive.com/roadmaps/go/maps/nil-maps

Repovive

Nil Maps - Maps | Go | Repovive

Repovive.

Go10 sections · 431 units20h total

Open in Course

Nil Maps

Uninitialized maps

A declared but uninitialized map is nil:

var ages map[string]int
fmt.Println(ages == nil)  // true
fmt.Println(len(ages))    // 0

_ = ages["Alice"]  // returns 0, no panic
ages["Alice"] = 30  // PANIC! assignment to nil map

You can read from a nil map safely. You cannot write to it. Always initialize maps with make or a literal before adding entries.