Interview Questions for Go Developer Position - Part II
Measuring And Classifying Go Developer Knowledge
Published on December 7, 2018
Go Developer InterviewAbout 3 minutes of reading.
Foreword
See part 1.
Q: What will return the following code?
func returnNormal() int {
i := 1
defer func() { i++ }()
return i
}
func returnNamed() (i int) {
i = 1
defer func() { i++ }()
return i
}
func main() {
fmt.Printf("returnNormal() = %d\n", returnNormal())
fmt.Printf("returnNamed() = %d\n", returnNamed())
}
A: returnNormal() = 1 and returnNamed() = 2 [3 points] (why : lazy evaluation)
Q: What will print the following code?
type Inner struct {}
type InnerAgain struct {}
type A struct {
Inner
InnerAgain
FieldA string
}
func (i Inner) String() string {
return "anything"
}
func (i InnerAgain) String() string {
return "nothing"
}
func main() {
myA := A{FieldA: "A"}
fmt.Printf("%v", myA)
}
A: {anything nothing A} [3 points] (why : ambiguous which String() to invoke)
Q: Can I convert a []T to an []interface{}?
A: Code below:
t := []int{1, 2, 3, 4}
s := make([]interface{}, len(t))
for i, v := range t {
s[i] = v
}
Q: Can I convert []T1 to []T2 if T1 and T2 have the same underlying type?
A: Code below:
type T1 int
type T2 int
var t1 T1
var x = T2(t1) // OK
var st1 []T1
Q: What’s wrong with the following code?
type info struct{
data string
}
test := []info{{data:"data 1"}, {data:"data 2"}, {data:"data 3"}}
list := make([]*string, 0)
for _, k := range test{
list = append(list, &k.data)
}
for _, s := range list {
fmt.Println(*s)
}
A: Don’t use pointers inside loops [1 point] A: Here. I’ve fixed it [3 points]
type info struct{
data string
}
test := []info{{data:"data 1"}, {data:"data 2"}, {data:"data 3"}}
list := make([]*string, 0)
for _, k := range test{
nk := k // the pointer
list = append(list, &nk.data)
}
for _, s := range list {
fmt.Println(*s)
}
Q: What will print the following code?
type People struct{}
func (p *People) ShowA() {
fmt.Println("showA")
p.ShowB()
}
func (p *People) ShowB() {
fmt.Println("showB")
}
type Teacher struct {
People
}
func (t *Teacher) ShowB() {
fmt.Println("teacher showB")
}
func main() {
t := Teacher{}
t.ShowA()
}
A: showA
showB [3 points]
Q: Does this compile ?
func main() {
i := GetValue()
switch i.(type) {
case int:
println("int")
case string:
println("string")
case interface{}:
println("interface")
default:
println("unknown")
}
}
func GetValue() int {
return 1
}
A: No [1 point]
A: No, because i is not an interface, so you cannot type switch on it [3 points]
Q: What will produce the following code ?
type Param map[string]interface{}
type Show struct {
Param
}
func main() {
s := new(Show)
s.Param["AValue"] = 10000
}
A : panic: assignment to entry in nil map [1 point]
Q: Does this compile ?
type student struct {
Name string
}
func printName(v interface{}) {
switch msg := v.(type) {
case *student, student:
fmt.Println(msg.Name)
}
}
A: No [1 point]
A: No, error will be type interface {} is interface with no methods [3 points]
Q: Is there a problem with the code below ?
type People struct {
Name string
}
func (p *People) String() string {
return fmt.Sprintf("print: %v", p)
}
func main() {
p := &People{}
p.String()
}
A: Yes [1 point] A: Yes, will recurse infinitely [3 points]
To be continued.
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