Zero-initialization is a source of confusion sometimes. They are default values for many types that are assigned even if you don't provide a value for the definition. Following are the zero-initialization for various types:
false
initialization for bool
type.0
values for int
type.0.0
for float
type.""
(empty strings) for string
type.nil
keyword for pointers, functions, interfaces, slices, channels and maps.struct
for structures without fields.struct
for structures with fields. The zero value of a structure is defined as the structure that has its fields initialized as zero value too.Zero-initialization is important when programming in Go because you won't be able to return a nil
value if you have to return an int
type or a struct
. Keep this in mind, for example, in functions where you have to return a bool
value. Imagine that you want to know if a number is divisible by a different number but you pass 0
(zero) as the divisor.
func main() { res := divisibleBy(10,0) fmt.Printf("%v ", res) } func divisibleBy(n, divisor int) bool { if divisor == 0 { //You cannot divide by zero return false } return (n % divisor == 0) }
The output of this program is false
but this is incorrect. A number divided by zero is an error, it's not that 10 isn't divisible by zero but that a number cannot be divided by zero by definition. Zero-initialization is making things awkward in this situation. So, how can we solve this error? Consider the following code:
func main() { res, err := divisibleBy(10,0) if err != nil { log.Fatal(err) } log.Printf("%v ", res) } func divisibleBy(n, divisor int) (bool, error) { if divisor == 0 { //You cannot divide by zero return false, errors.New("A number cannot be divided by zero") } return (n % divisor == 0), nil }
We're dividing 10
by 0
again but now the output of this function is A number cannot be divided by zero
. Error captured, the program finished gracefully.
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