Common pointer use cases in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a pointer to an integer variable.

Go

var x int = 10
var p [1] = &x

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

A*int

Bint*

C&int

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' instead of '*int' for pointer type.

Using '&int' which is invalid syntax.

Using 'int*' which is not Go syntax.

In Go, a pointer to an int is declared as *int. The & operator gets the address of x.

2fill in blank

medium

Complete the code to change the value of an integer through its pointer.

Go

var x int = 5
var p *int = &x
*p [1] 20

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

A=

B==

C:=

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' which is a comparison, not assignment.

Using ':=' which declares a new variable, not assignment.

Using '!=' which is a comparison operator.

To assign a new value through a pointer, use =. The expression *p = 20 changes the value of x to 20.

3fill in blank

hard

Fix the error in the code to correctly swap two integers using pointers.

Go

func swap(a, b [1] int) {
    temp := *a
    *a = *b
    *b = temp
}

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

A**

B&&

C&

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&int' which is invalid syntax.

Using '**int' which is a pointer to a pointer, not needed here.

Using '&&int' which is invalid.

The function parameters should be pointers to int, declared as *int. This allows swapping the values at the addresses.

4fill in blank

hard

Fill both blanks to create a map where keys are strings and values are pointers to integers.

Go

m := map[string][1]{}
m["score"] = [2]

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A*int

B&x

Cint

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' as map value type instead of '*int'.

Assigning 'x' instead of '&x' to the map value.

Using '&int' which is invalid.

The map values should be pointers to int, so *int. To assign a pointer, use the address operator & on a variable like x.

5fill in blank

hard

Fill all three blanks to define a struct with a pointer field, create an instance, and assign a value through the pointer.

Go

type Person struct {
    age [1]
}
p := Person{age: nil}
var a int = 30
p.age = [2]
*[3] = 35

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

A*int

B&a

Cp.age

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Declaring age as int instead of *int.

Assigning 'a' instead of '&a' to p.age.

Dereferencing wrong variable instead of p.age.

The struct field age is a pointer to int (*int). Assign the address of a to p.age. Then dereference p.age to change the value.