pointer to a pointer c++

[pieroborrelli]

Hello everyone ...... could you explain to me the difference between the 2 following codes:

 
#include <iostream>

int main()
{
	//example number 1 
	int ival = 10; 
	int *p = &ival; 

	int dval = 15; 
	int *p2 = &dval;

	p2 = p; //what happens when i assign p to p2 ? 


}

I believe that in the first case, if we assign the value of p to p2, p2 and p 2 pointers become equal and then we can access the object pointed to by p (ival) through both pointers ......


but i don't know what happens in this kind of code

#include <iostream>

int main()
{
	//example number 2 
	int ival = 1024; 
	int *p = &ival;
	int **ppi = &p; 




}

in this code p is a pointer to an int and ppi is a pointer to a pointer to an int...... what is the difference between assigning a pointer to another and make a pointer point to another pointer? with both codes can access an object indirectly via two pointers?

[JewelCpp]

In the first example it is like you said

if we assign the value of p to p2, p2 and p 2 pointers become equal and then we can access the object pointed to by p (ival) through both pointers

like if we write *p2=5; ival is changing

in the second it is a pointer to pointer
you can change p via ppi: *ppi=NULL; for example
you can also change ival: **ppi=6; or ++**ppi;

Edit: **ppi can be used as a dynamic bidimensional array