Address and dereference operators - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the address of variable num.

C

int num = 10;
int *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 symbols like # or % which are not address operators.

The address-of operator & gives the memory address of a variable.

2fill in blank

medium

Complete the code to access the value pointed to by pointer ptr.

C

int value = [1]ptr;

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

A*

B&

C->

D%

Attempts:

3 left

💡 Hint

Common Mistakes

Using the address-of operator (&) instead of dereference operator (*).

Using the arrow operator (->) which is for accessing members of a struct pointer.

The dereference operator * accesses the value stored at the memory address held by the pointer.

3fill in blank

hard

Fix the error in the code to correctly assign the value 20 to the variable pointed by ptr.

C

int num = 10;
int *ptr = #
[1]ptr = 20;

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

Aptr*

Bptr

C*

D&ptr

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning directly to the pointer variable instead of the value it points to.

Using incorrect syntax like ptr* or &ptr.

To change the value of the variable pointed by ptr, use the dereference operator *ptr.

4fill in blank

hard

Fill both blanks to create a pointer p that points to var and then access its value.

C

int var = 5;
int [1] p = [2]var;
int val = *p;

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

A*

B&

Cint

Dptr

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the asterisk in pointer declaration.

Assigning the pointer directly to the variable instead of its address.

Declare pointer p as int *p and assign it the address of var using &var.

5fill in blank

hard

Fill all three blanks to declare a pointer ptr, assign it the address of num, and then change the value of num to 100 using the pointer.

C

int num = 50;
[1] ptr = [2]num;
[3]ptr = 100;

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

Aint *

B&

C*

Dint

Attempts:

3 left

💡 Hint

Common Mistakes

Missing the asterisk in pointer declaration.

Assigning pointer directly to variable instead of its address.

Trying to assign value to pointer variable instead of dereferenced pointer.

Declare pointer as int *, assign address with &num, and change value using dereference *ptr.