Lære References 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


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#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

The format specifier used to print addresses (pointers) is %p.

Addresses are typically expressed in hexadecimal notation.

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


              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).

Oppgave

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 and dereference the address obtained.

Løsning

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Seksjon 6. Kapittel 2

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Can you explain the difference between the address-of and dereference operators with an example?

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Sveip for å vise menyen

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


              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

The format specifier used to print addresses (pointers) is %p.

Addresses are typically expressed in hexadecimal notation.

Dereference Operator

Note

Essentially, *&x is the same as x.

Main.c


              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).

Oppgave

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 and dereference the address obtained.

Løsning

Bytt til skrivebordet for virkelighetspraksisFortsett der du er med et av alternativene nedenfor

Alt var klart?

Takk for tilbakemeldingene dine!

Seksjon 6. Kapittel 2

single