Pointers and arrays in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a pointer to an integer.

C++

int* [1];

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

Aptr

Bpointer

Cp

DintPtr

Attempts:

3 left

💡 Hint

Common Mistakes

Using a type name instead of a variable name.

Forgetting the asterisk (*) to declare a pointer.

The code declares a pointer variable named ptr that can hold the address of an integer.

2fill in blank

medium

Complete the code to assign the address of variable num to pointer ptr.

C++

ptr = [1]num;

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

A#

B*

C&&

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using the dereference operator * instead of the address-of operator.

Using double ampersand && which is incorrect here.

The ampersand & operator gives the address of the variable num, which is assigned to the pointer ptr.

3fill in blank

hard

Fix the error in the code to access the first element of the array using a pointer.

C++

int arr[3] = {1, 2, 3};
int* ptr = arr;
int first = [1]ptr;

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

Aptr

B&

C*

D->

Attempts:

3 left

💡 Hint

Common Mistakes

Using the address-of operator & instead of dereference.

Using the arrow operator -> which is for pointers to structs or classes.

The dereference operator * is used to access the value pointed to by ptr, which is the first element of the array.

4fill in blank

hard

Fill both blanks to create a pointer that points to the third element of the array.

C++

int arr[5] = {10, 20, 30, 40, 50};
int* ptr = [1] + [2];

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

Aarr

B2

C3

D&arr

Attempts:

3 left

💡 Hint

Common Mistakes

Using &arr which is a pointer to the whole array, not the first element.

Adding 3 instead of 2 to point to the third element (index 2).

The pointer ptr is set to point to the element at index 2 (third element) by adding 2 to the array name arr.

5fill in blank

hard

Fill all three blanks to create a pointer to an array element and access its value.

C++

int nums[4] = {5, 10, 15, 20};
int* ptr = [1] + [2];
int val = *[3];

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

Anums

B1

Cptr

Dnums + 2

Attempts:

3 left

💡 Hint

Common Mistakes

Using nums + 2 for the first blank which is incorrect here.

Dereferencing nums instead of the pointer ptr.

The pointer ptr points to the second element (index 1) of the array nums. Then *ptr accesses the value at that position.