Address and dereference operators - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the address operator (&) do in C?

The address operator (&) gives the memory address of a variable. It tells where the variable is stored in memory.

beginner

What is the purpose of the dereference operator (*) in C?

The dereference operator (*) accesses the value stored at a given memory address (pointer). It lets you read or change the value the pointer points to.

beginner

Explain the difference between a pointer and a normal variable.

A normal variable stores a value directly. A pointer stores the address of another variable, not the value itself.

beginner

Given int x = 10; int *p = &x;, what does *p represent?

*p represents the value stored at the address held by p. Here, it is the value of x, which is 10.

intermediate

Why is it important to use the dereference operator carefully?

Using the dereference operator on an invalid or uninitialized pointer can cause errors or crashes because it tries to access memory that may not belong to your program.

What does the & operator do in C?

A Returns the address of a variable

B Dereferences a pointer

C Declares a pointer variable

D Assigns a value to a variable

The & operator returns the memory address of a variable.

If int *p = &x;, what does *p mean?

A The address of x

B A new pointer

C The value of x

D The size of x

*p accesses the value stored at the address pointed to by p, which is the value of x.

Which operator is used to get the value stored at a pointer's address?

A &

B *

C ->

D %

The * operator dereferences a pointer to get the value at the address.

What happens if you dereference a pointer that is not initialized?

A The program may crash or behave unpredictably

B You get the value zero

C It automatically initializes the pointer

D Nothing happens

Dereferencing an uninitialized pointer can cause crashes or undefined behavior.

Which of the following is a correct way to declare a pointer to an int?

A pointer int p;

B int p;

C int &p;

D int *p;

int *p; declares a pointer to an int.

Describe how the address (&) and dereference (*) operators work together with pointers in C.

Think about how you find where something is and then how you look inside it.

Explain why using the dereference operator on an invalid pointer is dangerous.

Consider what happens if you try to open a door that doesn't exist.