cpp-pointers


cpp-pointers

cpp Pointers

if p is a pointer

&p the memory address of p

*p the content that p points to

p the content of p (or the address that p points to)

Dynamic memory allocation or alias

Useful but dangerous…

.. code-block:: cpp

int p, q; // create two pointers, named p and q

p = new int; //

*p = 100;

q = p;

*q = 200;

q = new int;

q = p;

delete p; // give memory that p occupied back to operating system

p = NULL; // set p to memory address 0

delete q; // give memory that q occupied back to operating system

q = NULL; // set q to memory address 0

Dynamic Allocation for arrays

.. code-block:: cpp

int size = 5; // create an integer int *A; // create an array of
pointers

A = new int[ size ]; // Ask for a certain size for your array

A[0] = 10; // Give values to Array A[1] = 20; A[2] = 30; A[3] = 40; A[4]
= 50;

// 8 32 32 36 40 cout << &A << A << A + 0 << A + 1 << A + 2

// 10 28 30 cout << A[0] << A[1] << A[2]

// 10 10 28 30 cout << A << A + 0 << A + 1 << * A + 2

delete []A; A = NULL;