Introduction to C++

``Programming is the activity of communicating algorithms to computers.'' Kelly & Pohl.

C++ Keywords

The following keywords are part of the standard C++ language. They should not be used as identifiers for variables or functions. Keywords particular to C++ are shown in boldface.

asm	auto	break	case	catch
char	class	const	continue	default
delete	do	double	else	enum
extern	float	for	friend	goto
if	inline	int	long	new
operator	private	protected	public	register
return	short	signed	sizeof	static
struct	switch	template	this	throw
try	union	unsigned	virtual	void
volatile	while

Program Organization in C++

In a procedural language a program consists of static data and a collection of functions.

// Global data

int checking_balance, credit_balance, credit_limit;

// main procedure (function)

void main ()
{
    checking_balance = 1000;
    credit_balance = 500;
    credit_limit = 2000;
	
    int cost = 500;

    purchase (cost);
}

void purchase (int cost)
{
    if (cost < checking_balance)
      pay_by_cash (cost);
    else
      pay_by_credit (cost);
}

void pay_by_cash (int cost)
{
    checking_balance -= cost;
    if (checking_balance == 0) cout << "You're broke!";
    if (checking_balance < 0) 
      transfer_from_savings (abs(checking_balance));
}

void pay_by_credit (int cost)
{
    if (credit_balance + cost > credit_limit)
      cout << "You've exceeded your credit limit!";
    else
      credit_balance += cost;
}

C++ supports procedural programming. It also allows another more powerful form of organization known as object oriented programming.

// Classes
class CreditCard {
private:
    int balance;
    int limit;
public:
    void purchase (int cost);
};

class CheckingAccount {
private:
    int balance;
public:
    void purchase (int cost);
};

class Consumer {
private:
    CreditCard plastic;
    CheckingAccount checking;
public:
    Cosumer (int starting_balance, int credit_limit);
    void purchase (int cost);
    void pay_by_cash (int cost);
    void pay_by_credit (int cost);
};

void main ()
{
    Consumer Tom(100, 1000), Andrea(250, 5000);

    Tom.purchase (500);
    Andrea.purchase (120);
}

Each class is designed to represent a single concept. An instance of a class is called an object.

Intrinsic Types

Basic data types provided by C++ are

char	character
int	integer
long	long integer
float	single precision floating point
double	double precision floating point

The char, int, and long types may be signed or unsigned. The intrinsic types may be mixed in assignment expressions, e.g.

     int i = 10;
     unsigned long l;

     l = i;

The sizeof() operator may be used to determine the size in bytes of any type.

Operators

C++, like C, provides a rich set of operators which fall under the general categories

Relational Operators
Arithmetic Operators
Bitwise Operators
Logic Operators
Assignment Operators
Reference and Dereference Operators

The relational operators are

 ==     equal to 
 !=     not equal to
 <      less than
 >      greater than
 <=     less than or equal to
 >=     greater than or equal to

The arithmetic operators are

 +       add 
 -       subtract
 *       multiply
 /       divide
 %       remainder
 ++      increment
 --      decrement

The bitwise operators are

 &       bitwise AND
 |       bitwise OR
 ~       bitwise complement
 ^       bitwise XOR
 <<      bitwise left shift
 >>      bitwise right shift

The logic operators are

 &&      AND
 ||      OR
 !       NOT

The assignment operators are

 =       assignment
 +=      arithmetic assignment
 -=     
 *=
 /=
 %=
 <<=     bitwise assignment 
 >>=
 &=
 |=
 ^=

Flow Control Structures

C++ provides flow control structures for branching and looping like other structured languages. These are

if () {} else {}
if () {} else if () {} ... else {}
switch () { case 0: {} case 1: {} ... default: {}}
goto
while () {}
do {} while ()

The break and continue statements also control branching within loops.

Notes

All variables must be declared.
All functions must be declared.
A variable declared inside a function is local to that function.
Anything declared outside a function is visible to (may be referenced) by everything following the declaration.
Arrays have a starting index of 0.
Strings are arrays of type char with the last character being the null character.
Arguments to functions are passed by value in C. C++ supports passing by reference.

Functions in the C Standard Math Library

Be sure to include the math header file in any program that uses the math library functions.

#include <math.h>

Most of the functions take a double value as their argument, and return a double value. They would be declared as

double func (double x);

Name Description

acos Return arc cosine of

asin Return arc sine of

atan Return arc tangent of

atan2 Requires arc tangent of

atof Convert string to floating point number

ceil find smallest integer not less than

cos Return cosine of (radians)

cosh Return hyperbolic cosine of

exp Return

fabs Return absolute value of

floor Return largest integer not greater than

fmod Return remainder of

frexp Split argument into mantissa and exponent

ldexp Return value given mantissa and exponent

log Return natural logarithm of

log10 Return base 10 log of

modf Break a number into whole and fractional parts

pow Return

sin Return sine of (radians)

sinh Return hyperbolic sine of

sqrt Return positive square root of

tan Return tangent of (radians)

tanh Return hyperbolic tangent of

Name	Description
acos	Return arc cosine of
asin	Return arc sine of
atan	Return arc tangent of
atan2	Requires arc tangent of
atof	Convert string to floating point number
ceil	find smallest integer not less than
cos	Return cosine of (radians)
cosh	Return hyperbolic cosine of
exp	Return
fabs	Return absolute value of
floor	Return largest integer not greater than
fmod	Return remainder of
frexp	Split argument into mantissa and exponent
ldexp	Return value given mantissa and exponent
log	Return natural logarithm of
log10	Return base 10 log of
modf	Break a number into whole and fractional parts
pow	Return
sin	Return sine of (radians)
sinh	Return hyperbolic sine of
sqrt	Return positive square root of
tan	Return tangent of (radians)
tanh	Return hyperbolic tangent of