Notice: This page requires JavaScript to function properly.
Please enable JavaScript in your browser settings or update your browser.Lära References and Dereferences | Pointers
C Basics

bookReferences and Dereferences

Pointers are built around two operators:

  • The address-of operator &.
  • The dereference operator *.

Address-of Operator

The address-of operator, represented by &, allows us to directly interact with our computer's RAM. Using & lets you obtain the actual memory address of an object.

Main.c

Main.c

copy

              
123456789101112

            
#include <stdio.h>

int main()
{
    int x = 100;

    printf("Value of variable: %d\n", x);

    printf("Address of variable into RAM: %p\n", &x); // using reference operator `&` for getting address

    return 0;
}

Note

%p is the format specifier used for addresses (pointer).

Addresses are typically expressed in hexadecimal notation.

Think of the & operator as identifying your home's address using your name.

Dereference Operator

Conversely, the * operator gives you the resident's name when given their address. So, how can we employ this operator if we're not directly dealing with addresses? If you have an expression like &x, which returns the address of the x variable, applying the * operator to it (*&x) gives you the value of the variable stored at that address.

Note

Essentially, *&x is the same as x.

Main.c

Main.c

copy

              
1234567891011121314

            
#include <stdio.h>

int main()
{
    int x = 100;

    printf("Value of variable: %d\n", x);

    printf("Address of variable in RAM: %p\n", &x); // using reference operator `&`

    printf("Dereferencing address of variable: %d", *(&x)); // using dereference operator `*`

    return 0;
}

Note

Don't mix up the dereference operator (*x) with the multiplication operator (x*y).

Uppgift

Swipe to start coding

  • Create an integer array of 5 elements and populate it.
  • Retrieve the address of the third element.
  • Increment the address of the third element (i.e., address + 1).
  • Attempt to dereference the address obtained in the previous step.

Lösning

Switch to desktopByt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan
Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

Avsnitt 6. Kapitel 2
single

single

Fråga AI

expand

Fråga AI

ChatGPT

Fråga vad du vill eller prova någon av de föreslagna frågorna för att starta vårt samtal

close

Awesome!

Completion rate improved to 2.63

bookReferences and Dereferences

Pointers are built around two operators:

  • The address-of operator &.
  • The dereference operator *.

Address-of Operator

The address-of operator, represented by &, allows us to directly interact with our computer's RAM. Using & lets you obtain the actual memory address of an object.

Main.c

Main.c

copy

              
123456789101112

            
#include <stdio.h>

int main()
{
    int x = 100;

    printf("Value of variable: %d\n", x);

    printf("Address of variable into RAM: %p\n", &x); // using reference operator `&` for getting address

    return 0;
}

Note

%p is the format specifier used for addresses (pointer).

Addresses are typically expressed in hexadecimal notation.

Think of the & operator as identifying your home's address using your name.

Dereference Operator

Conversely, the * operator gives you the resident's name when given their address. So, how can we employ this operator if we're not directly dealing with addresses? If you have an expression like &x, which returns the address of the x variable, applying the * operator to it (*&x) gives you the value of the variable stored at that address.

Note

Essentially, *&x is the same as x.

Main.c

Main.c

copy

              
1234567891011121314

            
#include <stdio.h>

int main()
{
    int x = 100;

    printf("Value of variable: %d\n", x);

    printf("Address of variable in RAM: %p\n", &x); // using reference operator `&`

    printf("Dereferencing address of variable: %d", *(&x)); // using dereference operator `*`

    return 0;
}

Note

Don't mix up the dereference operator (*x) with the multiplication operator (x*y).

Uppgift

Swipe to start coding

  • Create an integer array of 5 elements and populate it.
  • Retrieve the address of the third element.
  • Increment the address of the third element (i.e., address + 1).
  • Attempt to dereference the address obtained in the previous step.

Lösning

Switch to desktopByt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan
Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

Avsnitt 6. Kapitel 2
single

single

close

Awesome!

Completion rate improved to 2.63

bookReferences and Dereferences

Svep för att visa menyn

Pointers are built around two operators:

  • The address-of operator &.
  • The dereference operator *.

Address-of Operator

The address-of operator, represented by &, allows us to directly interact with our computer's RAM. Using & lets you obtain the actual memory address of an object.

Main.c

Main.c

copy

              
123456789101112

            
#include <stdio.h>

int main()
{
    int x = 100;

    printf("Value of variable: %d\n", x);

    printf("Address of variable into RAM: %p\n", &x); // using reference operator `&` for getting address

    return 0;
}

Note

%p is the format specifier used for addresses (pointer).

Addresses are typically expressed in hexadecimal notation.

Think of the & operator as identifying your home's address using your name.

Dereference Operator

Conversely, the * operator gives you the resident's name when given their address. So, how can we employ this operator if we're not directly dealing with addresses? If you have an expression like &x, which returns the address of the x variable, applying the * operator to it (*&x) gives you the value of the variable stored at that address.

Note

Essentially, *&x is the same as x.

Main.c

Main.c

copy

              
1234567891011121314

            
#include <stdio.h>

int main()
{
    int x = 100;

    printf("Value of variable: %d\n", x);

    printf("Address of variable in RAM: %p\n", &x); // using reference operator `&`

    printf("Dereferencing address of variable: %d", *(&x)); // using dereference operator `*`

    return 0;
}

Note

Don't mix up the dereference operator (*x) with the multiplication operator (x*y).

Uppgift

Swipe to start coding

  • Create an integer array of 5 elements and populate it.
  • Retrieve the address of the third element.
  • Increment the address of the third element (i.e., address + 1).
  • Attempt to dereference the address obtained in the previous step.

Lösning

Switch to desktopByt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan
Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

some-alt