if *p indicates the value then what does **p or ***p indicate?? Many question in challenges also contain *&p and *p*

Answer 1

First of all, you should understand how pointers work. A pointer is a variable whose value is the address memory of another variable –that is, it's position in the computer memory.
Take, for example, this case:
variable i, value 23, address 0x000001
variable *p, value 0x000001, address 0x000002
Now i == 23, p == 0x000001 (this is easy).
The crucial fact here is that *p == 23, because *p means "take the value of p, interpret it as a memory address, and fetch the value of that address". So it is said that *p "points to" i.

The other way around, &p stands for the memory address of p, rather than its value. So &i == 0x000001 and &p == 0x000002.

Answer 2

int a=0; a is a int value
int *p; p is a pointer (a variable that can contains a int variable adress)

so you can write it :

p = &a; because &var return the adress of var.

Now : *p will return the value of a and &p the adress of p. If you want to store the adress of the p variable, you have to create a pointer for int pointers like this :

int ** p2 = &p;

so &p2 return the adress of p2. And *p2 return p so **p2 return *p = a.

Note that the * can also be used for multiplication. You can for example have this :

int b = **p2 * *p * a * **p2;
= a * a * a * a;

Answer 3

See also :

https://www.sololearn.com/discuss/343297/?ref=app

https://code.sololearn.com/c4QlynzIZQ4o/?ref=app