Empty interface in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a variable that can hold any type using the empty interface.

Go

var data [1]

Drag options to blanks, or click blank then click option'

Aint

Binterface{}

Cstring

Dstruct{}

Attempts:

3 left

💡 Hint

Common Mistakes

Using a concrete type like int or string instead of the empty interface.

Using struct{} which is an empty struct, not an interface.

The empty interface interface{} in Go can hold values of any type.

2fill in blank

medium

Complete the code to assign a string value to an empty interface variable.

Go

var value interface{}
value = [1]

Drag options to blanks, or click blank then click option'

A"hello"

B100

Ctrue

Dnil

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning a number or boolean when a string is expected.

Forgetting to use quotes around the string.

You can assign any value to an empty interface variable. Here, a string literal must be in quotes.

3fill in blank

hard

Fix the error in the code by completing the type assertion from an empty interface to int.

Go

var data interface{} = 42
num := data.[1]

Drag options to blanks, or click blank then click option'

A(int)

Bcast

Ctype

Dassert

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cast' or 'type' which are not Go keywords for this.

Trying to use slice notation like ([]int).

In Go, to get the concrete value from an interface, you use a type assertion: data.(int).

4fill in blank

hard

Fill both blanks to create a map from string to empty interface and assign a value.

Go

data := map[string][1]{
	"key": [2],
}

Drag options to blanks, or click blank then click option'

Ainterface{}

B"value"

Cint

Dnil

Attempts:

3 left

💡 Hint

Common Mistakes

Using int as the map value type when it should be interface{}.

Assigning a string value without quotes.

The map value type is the empty interface interface{} to hold any type. The value assigned is a string literal.

5fill in blank

hard

Fill all three blanks to create a slice of empty interfaces and append a boolean value.

Go

var items [][1]
items = append(items, [2])
fmt.Println(items[[3]])

Drag options to blanks, or click blank then click option'

Ainterface{}

Btrue

C0

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using false instead of true for the appended value.

Using 1 instead of 0 for the slice index.

The slice holds empty interfaces. We append a boolean true. The first element is at index 0.