Pointer arithmetic - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to access the next element using pointer arithmetic.

C

int arr[] = {10, 20, 30};
int *ptr = arr;
int value = *(ptr [1] 1);

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

A/

B-

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' moves the pointer backward, which is incorrect here.

Adding 1 to the pointer moves it to the next integer element in the array.

2fill in blank

medium

Complete the code to calculate the number of elements between two pointers.

C

int arr[] = {5, 10, 15, 20};
int *start = &arr[0];
int *end = &arr[3];
int diff = end [1] start;

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' will not give the distance between pointers.

Subtracting two pointers gives the number of elements between them.

3fill in blank

hard

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

C

int nums[] = {1, 2, 3, 4};
int *p = nums;
int val = *(p[1] 2);

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

A+

B*

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' or '/' causes syntax errors.

To access the third element, add 2 to the pointer before dereferencing.

4fill in blank

hard

Fill both blanks to create a pointer that points to the second element and then access it.

C

int data[] = {7, 14, 21};
int *ptr = data [1] 1;
int val = [2]ptr;

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' moves pointer backward incorrectly.

Using '/' or other operators causes errors.

Adding 1 moves the pointer to the second element. Dereferencing with '*' accesses the value.

5fill in blank

hard

Fill all three blanks to create a pointer to the last element, subtract 2 to get the first, and dereference it.

C

int vals[] = {3, 6, 9};
int *p = vals [1] 2;
int *q = p [2] 2;
int result = [3]q;

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing '+' and '-' incorrectly.

Using '/' causes errors.

Adding 2 moves pointer to last element, subtracting 2 moves back to first, dereferencing with '*' gets the value.