I really don't understanding pointers, so I need someone to help me.

Answer 1

Every variable you have needs to be stored somewhere in memory.
int x = 5; /* the 5 is now stored somewhere */
To find out where you can use &x. This gives you the location of x in memory (= the pointer to x). Let's make a new pointer and let it point to x. As x stores an integer value we'll need a pointer that points to an integer:
int *p; /* this is the pointer p */
p = &x; /* p now points at x */
To access the value of x with p we can use *p:
*p = 10; /* now x is 10. it's always good to cout all the values if you're not sure how they've changed */

Now arrays are technically also pointers.
int a[10]; /* a is a pointer that points to the first element of the array */
To get the first element of an array you normaly write a[0], but as a is also a pointer you can use *a for the same result. For the second element you'd normaly use a[1]. But as all the elements of an array are stored at the same location in memory one after the other you can just increase the pointer by 1 (= let it point to the next space in memory) and you'll get the second element of the array again:
*(a+1) = 6; /* sets the value of a[1] to 6 */
In general a[n] is the same as *(a+n) and (a+n) is the same as &a[n] (location of an element in the array a).

Of corse pointers are also just values (they store a number, you can cout them and you'll see to what memory address they point), so you can also create a pointer to a pointer:
int x = 5;
int *p = &x;
int **pp = &p;
You can even access x with pp via **pp.

Pointers are often used in function if you want to return more than one value. You give the function a pointer to a value and then the function can change the original value:

EDIT: Looks like the comment is too long and the rest got cut off so I'll post it in a new reply!

Answer 2

What didn't fit into my first reply:

Pointers are often used in function if you want to return more than one value. You give the function a pointer to a value and then the function can change the original value:

void func(int *x){
*x *= 2; /* don't forget x is a pointer, to access its value you need *x! */
}

int main(){
int x = 8;
func(&x); /* func needs a pointer to an integer so we can't just use func(x);, instead we give it the pointer to x */
cout << x << endl; /* even though func doesn't return anything and we didn't change x in main it will still output 16 now */
return 0;
}

Answer 3

// declaring different types of pointers

int* p;
char* q;
double* r;

// using pointer to point to the address of a variable, let's say, variable x.

p = &x;

// utilising the pointer

cout << *p;

// I know these will not be enough, so it would be good if you can query in specific what you don't understand about pointers.

Answer 4

Using pointers in programming is like juggling soap bars in prison, it's fun until you make a mistake...

Answer 5

basically, if I have variable and I want another variable have the same value of that variable and any one of them can change the value and the other can see this change. so in this case we need the pointer.
for example:
int x= 10;
int *p=&x;
in this case x and p have the same value, and any change can make x or p .it will effect on both.
the both share the same value.
if I make
x=5;
now also p will be 5 too
hopefully what I said is right. thanks

Answer 6

let's understand it with real world example..
suppose I want to access you to invite you for my birthday party
then I have 2 options
1) I can directly invite you for that I can simply use your name
LivingStone = "you are invited";
this is equivalent to accessing a variable by its name,. ex:
x = 10;
2) I can invite you at your address for that
first I have to get your address on a postcard(pointer)
string *yourAddress;
//making a postcard, using * to know that it's a postcard.
yourAddress = "address of LivingStone";
//writing your address on the postcard
then I can invite you as
*yourAddress = "you are invited";.
// here * means traveling to your address and then inviting you, it is nothing to do with the * used in declaration

This is equivalent to accessing a variable through its address,
ex:
int *p;
//use * to declaration a pointer
p = &x;.
// first store the address of x in p
*p = 10;
// assign 10 to x using it's address which is already stored in p.

Answer 7

Pointers are just like a reference variable who refer to the address of variable,object, arrays and array of character (string)...

Answer 8

I am starting my answer with the Concept of RAM.
as we all know that RAM consist of memory cell and each cell having a size of 1 byte also each cell having a address(hexadecimal format say 0x1555).
When a declare a variable say int x it acquire a 2 byte (it means it reserve 2 memory cell in ram in consecutive manner) now
let's us suppose we assigning a value to variable x =2; the value will store in location 0x1555.
In general programming we r accessing this location using variable(actually variable is nothing just a name of particular memory cells in RAM) for easy understanding. Which is indirect way of accessing the memory . In pointer we are accessing value which is in RAM directly manner that's why pointer is so fast and it has both advantage and disadvantage.
Now
When we declare a variable as a pointer variable it store Address of some particular variable(memory location )

Answer 9

a pointer point to the address of variable it contains the address of variable not a value of variable

Answer 10

They point to a certain address

Answer 11

Pointer is just a storage area which stores the address of a variable.It tells us that the variable is stored at x location in the memory.

Answer 12

hello,
in simple terms pointers points to some memory location.So what is a memory location?
whenever we declare a variable, some space is allocated in the memory. Each allocated space is associated with an address(represented in hexadecimal, e.g 0xaaff1d). whenever we assign a value to a variable , a value is associated with that address.
pointer is a variable that holds the address of another variable.example,

int a = 10;

//lets assume that addrs of variable a is 0xAD12E6
//value of variable a is 10

int *p = &a;

//variable p is a pointer to an integer
//lets assume that addrs of variable p is 0x11AA44
//However value of p is the address of variable a, that is 0xAD12E6

There are two types of operator :

& - address of operator...it returns the address of a variable as in the example above.

* - value at address operator

let us print the value of variable a using pointer p
c++ code :

cout<< *p; //outputs 10

pointer variable p had the address of variable a
using '*' operator returns the value at that address

cout<< *(&a); //outputs 10

Answer 13

A pointer simply is just a variable that holds the location of where another hunk of data is located in memory.

Imagine a person named John Doe, who has a girlfriend named Jane Doe. He needs to get to his girlfriends house for movie night. How does he do this? He reaches into his back pocket and pulls out a piece of paper with her address on it and then drives to her house.

So John Doe is the pointer variable. Jane Doe is the data that John's address book is pointing to. John could not get to Jane's house with the ADDRESS. Same thing applies to programming. The computer is just storing the ADDRESS or LOCATION in memory, of where another piece of data is located in memory.

Get my point? (pun intended)

Answer 14

Wow nice one!
I also get confused on this pointer issue.
But i think i understand now.
Thanks to all the contributors

Answer 15

a pointer has an address of a variable
for example int x=7
if x is located at address memory of 0x4567
*p contain 0x4567 not 7

Answer 16

mostly its a relic from the legacy era

Answer 17

pointer is variable itself.
it stores the address of another variable in the memory.
example :

*p= &x;

it read as : a pointer p has address of x

Answer 18

*p Is a pointer
** Is a pointer to a pointer
***p is a pointer to a pointer to a pointer
*&p is a pointer to an address

The best way to understand pointers is to play with them.

Reading about them also helps.

Answer 19

Can someone also tell me why we need pointers?

Answer 20

pointer is simply used to store address of other variable.. for example, if we r designing a linked list..we need to create links ..these links r made by pointers
hope u got it :)