Pointers to pointers in C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

C

int x = 10;
int *p = &x;
int [1] = &p;

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

A**pp

B*pp

Cpp

D&pp

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one asterisk (*) instead of two.

Forgetting to use a pointer type for pp.

The declaration int **pp means pp is a pointer to a pointer to an integer.

2fill in blank

medium

Complete the code to assign the address of pointer p to pointer to pointer pp.

C

int x = 5;
int *p = &x;
int **pp;
pp = [1];

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

Ap

B&p

C*p

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning pp = p; which is incorrect type.

Assigning pp = *p; which dereferences p.

To make pp point to p, assign pp = &p; because pp is a pointer to a pointer.

3fill in blank

hard

Fix the error in the code to correctly print the value of x using pointer to pointer pp.

C

int x = 20;
int *p = &x;
int **pp = &p;
printf("%d\n", [1]);

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

A*pp

Bpp

C**pp

D*p

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one dereference *pp which gives pointer p, not value.

Using pp directly which is a pointer to pointer.

To get the value of x through pp, you need to dereference twice: **pp.

4fill in blank

hard

Fill both blanks to correctly change the value of x to 50 using pointer to pointer pp.

C

int x = 10;
int *p = &x;
int **pp = &p;
**pp = [1];
printf("%d\n", [2]);

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

A50

Bx

C**pp

D*p

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to assign value to *pp instead of **pp.

Printing **pp instead of *p.

Assigning **pp = 50; changes x to 50. Printing *p shows the updated value.

5fill in blank

hard

Fill all three blanks to create a pointer to pointer, assign it, and print the value of x.

C

int x = 100;
int *p = &x;
int [1] = &p;
printf("%d\n", [2]);

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

A**pp

B*p

Dpp

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing pointer declaration syntax.

Using wrong dereference level when printing.

Declare pp as int **pp, print value with *p or **pp. Here, pp is the pointer to pointer.