Zero values

Variables in Go are initialized with a known value if not explicitly assigned.

That value is knows as zero value.

This is different from C/C++, where variables that are not explicitly assigned have undefined values.

The values of zero type are unsurprising:

type	zero value
bool	false
integers	0
floating point numbers	0.0
string	""
pointer	nil
slice	nil
map	nil
interface	nil
channel	nil
array	all elements have zero value
struct	all members set to zero value
function	nil

Said differently:

 fmt.Println("zero values for basic types:")

var zeroBool bool
fmt.Printf("bool:       %v\n", zeroBool)

var zeroInt int
fmt.Printf("int:        %v\n", zeroInt)

var zeroF32 float32
fmt.Printf("float32:    %v\n", zeroF32)

var zeroF64 float64
fmt.Printf("float64:    %v\n", zeroF64)

var zeroStr string
fmt.Printf("string:     %#v\n", zeroStr)

var zeroPtr *int
fmt.Printf("pointer:    %v\n", zeroPtr)

var zeroSlice []uint32
fmt.Printf("slice:      %v\n", zeroSlice)

var zeroMap map[string]int
fmt.Printf("map:        %#v\n", zeroMap)

var zeroInterface interface{}
fmt.Printf("interface:  %v\n", zeroInterface)

var zeroChan chan bool
fmt.Printf("channel:    %v\n", zeroChan)

var zeroArray [5]int
fmt.Printf("array:      %v\n", zeroArray)

type struc struct {
	a int
	b string
}
var zeroStruct struc
fmt.Printf("struct:     %#v\n", zeroStruct)

var zeroFunc func(bool)
fmt.Printf("function:   %v\n", zeroFunc)

try online

zero values for basic types:
bool:       false
int:        0
float32:    0
float64:    0
string:     ""
pointer:    <nil>
slice:      []
map:        map[string]int(nil)
interface:  <nil>
channel:    <nil>
array:      [0 0 0 0 0]
struct:     main.struc{a:0, b:""}
function:   <nil>

Found a mistake? Have a question or improvement idea? Let me know.

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