What does golang nil mean?

Everyone knows that when you declare a variable but do not assign a value, golang will automatically give your variable type a corresponding default zero value.

This is the zero value corresponding to each type:                             (Recommended learning: go)

bool      -> false                              
numbers -> 0                                 
string    -> ""      

pointers -> nil
slices -> nil
maps -> nil
channels -> nil
functions -> nil
interfaces -> nil

Another strcut:

type Person struct {
  Age int
  Name string
  Friends []Person
}

var p Person // Person{0, "", nil}

The variable p is only declared but not assigned, so all fields of p have corresponding zero values.

1. Go’s documentation says that nil is a predefined identifier that represents the zero value of a pointer, channel, function, interface, mapping or slice. It is not one of the keywords of GO.

2. nil can only be assigned to pointer, channel, func, interface, map or slice type variables (non-basic types), otherwise pani will be triggered

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