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] ptr;

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

A*

B&

C#

D%

Attempts:

3 left

💡 Hint

Common Mistakes

Using & instead of * to declare a pointer.

The asterisk (*) is used to declare a pointer variable in C.

2fill in blank

medium

Complete the code to access the first element of the array using a pointer.

C

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

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

Aarr[1]

Bp[1]

C&arr[0]

D*p

Attempts:

3 left

💡 Hint

Common Mistakes

Using p[1] which accesses the second element, not the first.

The expression *p dereferences the pointer to get the first element of the array.

3fill in blank

hard

Fix the error in the pointer arithmetic to access the third element.

C

int arr[4] = {10, 20, 30, 40};
int *p = arr;
int val = *[1];

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

Ap - 2

Bp + 2

Carr + 3

D&p + 2

Attempts:

3 left

💡 Hint

Common Mistakes

Using p - 2 which moves pointer backwards.

Adding 2 to pointer p moves it to the third element, then dereferencing gets its value.

4fill in blank

hard

Fill both blanks to create a pointer to the second element and get its value.

C

int nums[5] = {5, 10, 15, 20, 25};
int *ptr = nums [1] 1;
int value = *[2];

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

A+

B-

Cptr

Dnums

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' to move forward in the array.

Adding 1 to the array name points to the second element. Dereferencing ptr gets its value.

5fill in blank

hard

Fill all three blanks to create a pointer, move it, and access the value correctly.

C

int data[4] = {2, 4, 6, 8};
int *p = [1];
p = p [2] 3;
int val = *[3];

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

Adata

B+

Cp

D&data

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&data' which is pointer to the whole array, not first element.

Pointer p starts at data, moves forward 3 elements, then dereferenced to get the value.