{

//pointers1();

pointers2();

return 0;

{

int *p1, *p2, v1, v2; // declares 2 integer pointers and 2 normal int variables.

v1 = 0;

v2 = v1;

p1 = &v1; // assigns the address of variable v1 to the pointer p1

*p1 = 42;

p2 = p1; // assigns the address location of the pointer p1 to p2 so they both point to the same location;

cout << "v1 = " << v1 << endl;

cout << "v2 = " << v2 << endl;

cout << "*p1 = " << *p1 << endl; // prints the value stored in memory pointed to by pointer p1

cout << "*p2 = " << *p2 << endl; // prints the value stored in memory pointed to by pointer p2

cout << endl << "&v1 = " << &v1 << endl; // prints the address of the variable v1

cout << "p1 = " << p1 << endl; // prints the address pointed to by pointer p1 (same as the above)

cout << "&p1 = " << &p1 << endl; // prints the address of the pointer p1

p2 = &v2; // assigns the address of variable v2 to the pointer p2

*p2 = 89; // assigns the value 89 to the variable pointed to by p2

cout << endl << "v1 = " << v1 << endl;

cout << "v2 = " << v2 << endl;

cout << "*p1 = " << *p1 << endl;

cout << "*p2 = " << *p2 << endl;

*p1 = *p2; // assigns the value pointed to by p2 into the variable referenced by p1

cout << endl << "v1 = " << v1 << endl;

cout << "v2 = " << v2 << endl;

cout << "*p1 = " << *p1 << endl;

cout << "*p2 = " << *p2 << endl;

{

int *p1, *p2; // the * is referred to as the "dereferencing operator"

p1 = new int; // creates an unnamed dynamic variable of type int denoted by pointer p1

*p1 = 42; // "Assign the value 42 to the variable pointed to by p1"

p2 = p1;

cout << "*p1 = " << *p1 << endl; // value of the variable stored where pointer points to

cout << "*p2 = " << *p2 << endl;

cout << "&p1 = " << &p1 << endl; // memory location of the pointer p1

cout << "p1 = " << p1 << endl; // memory location of the variable pointed to by p1

*p2 = 53;

cout << endl << "*p1 = " << *p1 << endl;

cout << "*p2 = " << *p2 << endl;

p1 = new int;

*p1 = 88;

cout << endl << "*p1 = " << *p1 << endl;

cout << "*p2 = " << *p2 << endl;

int *p;

p = new int; // dynamic variables are created and destroyed while the program is running.

*p = 777; // dynamic variables are stored in "freestore" aka "heap" memory

cout << endl << "*p = " << *p << endl;

cout << "p = " << p << endl;

delete p; // eliminates the dynamic variable created in line 46. Unfortunately this creates a "dangling pointer"

cout << endl << "*p = " << *p << endl; // supposed to be an undefined address and can result in unpredictable behavior

cout << "p = " << p << endl; // value is supposed to be now undefined, since the pointer is "dangling"

typedef int *IntPtr; // deefines a type "IntPtr" that is a type for pointer variables that are pointers to int variables

IntPtr p3; // same as declaring "int *p3"

p3 = new int; // dynamic variable allocation for pointer p3

*p3 = 999; // sets value of the dynamic variable to 999

cout << endl << "*p3 = " << *p3 << endl << endl;

int *p4 = NULL; // sets pointer to a NULL value - p3 is now "dangling"

int *p5 = 0; // another way to set a pointer to NULL value (also dangling)

cout << "p4 == NULL is: " << boolalpha << (p4 == 0) << endl; // boolalpha flag is set until its unset with "noboolalpha"

cout << "p5 == 0 is: " << (p5 == 0) << endl << endl;

//cout << "*p3 = " << *p3 << endl; // dereferencing a NULL pointer results in a segmentation fault since the memory location is NULL.

int var1 = 25, var2 = 55, var3, var4;

int *ptr4, *ptr5, *ptr6, *ptr7;

ptr4 = &var1; // sets pointer to the address location of the variable.

ptr5 = &var2;

ptr6 = &var3;

ptr7 = &var4;

*ptr6 = 111; // assigns value 111 to var3 via the pointer dereferncing

*ptr7 = 222; // assigns value 222 to var4 via the pointer dereferncing

cout << "The value stored at var1 = " << *ptr4 << endl

<< "The value stored at var2 = " << *ptr5 << endl

<< "The value stored at var3 = " << *ptr6 << endl

<< "The value stored at var4 = " << *ptr7 << endl << endl;

int array1[100][100][100];

cout << "sizeof(int array1[]) = " << sizeof(array1[10]) << endl;

}