#include <iostream.h>

int VarInt;
// This has created an int variable called VarInt

unsigned int PosVar;
// This created a variable int that can only hold
// positive numbers

signed int NegVar;
// This created a variable int that can only hold
// negative numbers

double Pi = 3.14;
// This has created a double and assigned the value 3.14 to it

int main()
{
	cout << "Enter a positive number: ";
	cin >> PosVar;
	cout << "Enter a negative number: ";
	cin >> NegVar;
	cout << "Enter a number negative or positve: ";
	cin >> VarInt;
	cout << "PosVar: " << PosVar << endl;
	cout << "NegVar: " << NegVar << endl;
	cout << "VarInt: " << VarInt << endl;
	cout << "Pi: " << Pi << endl;
	return 0;
}

#include <iostream.h>

const double PI = 3.14;
// this makes a double named PI with the value of 3.14
// that cannot be changed.

const int TWO = 2;
// this makes an int named TWO with the value of 2
// that cannot be changed.

long Radius;
// this makes a long named Radius that it's value
// CAN be changed.

float Area;
// this makes a float named Area that it's value
// CAN be changed.

int main()
{
	cout << "Enter the Radius: ";
	cin >> Radius;
	// this next part may look a little greek for now
	// but this is just to demonstrate that the PI and
	// TWO are not changed.
	Area = (Radius * TWO)* PI;
	cout << "The area is: " << Area;
	return 0;
}

#include <iostream.h>

int main()
{
	int * p = 0; // The pointer is initiated to hold
		     // data the size of an int. Then the
		     // pointer is assigned to 0. Don't ask
		     // Why just always do it that way.

	int a;
	cout << "a: ";
	cin >> a;
	p = & // The & operator is also known as the 'address'
		// operator. If it is put in front of a variable
		// then the variable returns it's address instead
		// of the data held in that address. Here we see 
		// the address of a is being assinged to p;

	cout <<  "*p: " << *p; // The * before a pointer makes the pointer
			   // return the value stored in the address
			   // that the pointer is holding.

	cout  << "p: " << p; // Without the * the pointer just returns
			 // the address that it is holding.

	cout << "*p: ";
	cin >> *p; // Note the * in front of the pointer, this tells you that
		   // you are assigning the input to the address, and not the
		   // pointer.

	cout << "a: " << a; 	// If this was compiled and ran this would
				// return the value you just assigned to the
				// *p.

	return 0;
}

#include <iostream.h>

int main()
{
	int Var = 3;
	int * Pointer2Var = &Var;
	int * Pointer2FS = new int;
	if(Pointer2FS == NULL)
	{
	 cout << "ERROR: Not Enough Memory!" << endl;
	 return 0;
	}
	*Pointer2FS = 5;
	cout << "Var: " << Var << endl;
	cout << "Pointer2FS: " << *Pointer2FS << endl;
	cout << "Pointer2Var: " << *Pointer2Var << endl;
	delete Pointer2FS;
	Pointer2FS = new int;
	if(Pointer2FS == NULL)
	{
	 cout << "ERROR: Not Enough Memory!" << endl;
	 return 0;
	}
	*Pointer2FS = 9;
	cout << "Pointer2FS: " << *Pointer2FS << endl;
	delete Pointer2FS;
	return 0;
}