C++ Notes: Summary - Basic Elements

Basics

Comments

// This comment terminates at end of line.
/* Comment (possibly many lines) terminates at */

Reserved Words


asm auto bool break 
case catch
char class const const_cast continue
default delete do double dynamic_cast
else  enum explicit export extern 
false float for friend goto
if inline int long mutable
namespace new
operator private protected public
register reinterpret_cast return
short signed sizeof static static_cast
struct switch template this throw
true try typedef typeid typename union
unsigned using virtual void volatile
wchar_t while

Operators and Puctuation

() {} [] + - * / % ++ -- < <= == != >= > && || ! << >> ?: ; , . = += -= ...
& | ^ ~ :: -> ->* .*

Identifiers

Start identifiers with an alphabetic character (a-z or A-Z), and continue with alphabetic, numeric (0-9), or '_' (underscore) characters.
Second words in a name should start with an uppercase letter.
Do not use keywords (see below).
Constants should be all uppercase (X_AXIS, Math.PI, ...).

Simple and String Types

Integer Types

The integer types: char, short, int, long, and bool are binary integers. All except bool are signed (char is usually signed), but can be declared unsigned. Below are some typical characteristics of the basic types. The standard allows compilers to have different implementations.

Type	Bytes	Range (signed)	Range (unsigned)	Literals
bool	1	0..1		false, true
char	1	-128..+127	0..255	'a'
short	2	-32,768..+32,767	0..65,535	none
int	4	-2,147,483,648..+2,147,483,647	0..4,294,967,295	23, 0xAF
long	4	-2,147,483,648..+2,147,483,647	0..4,294,967,295	23L, 0xAFL

Operators: arithmetic, comparison, bitwise, assignment.

Floating-point Types

The floating-point types, float and double, are usually stored in IEE-754 format. Calculations may produce NaN (Not a Number); or positive or negative infinity.

Type	Bytes	Range	Accuracy	Literals
float	4	-3.4E38..+3.4E38	6-7 digits	3.14F 6.02e23F
double	8	-1.7E308..+1.7E308	14-15 digits	3.14 6.02e23
long double	12	??-??	?? digits

Operators: arithmetic, comparison, assignment.

Characters

Characters are stored in one byte (char) or two bytes (wchar_t). char is an integer type.
Literals

'A' // one character in single quotes.
Double quotes ("") are used to enclose strings which may have zero or more characters, eg, "Hello".
Hexadecimal '0xnn' where x is a hexadecimal digit. Eg '0x41'
Octal '\nnn' where n is an octal digit.
Escape combinations: '\n' newline, '\\' backslash, '\'' single quote, '\"' double quote, '\r' carriage return, '\t' tab, '\b' backspace, '\f' form feed.

C-strings

C-strings are arrays of chars with a terminating zero ('\0'). Enclose C-string literals in double quotes. C-strings are type char[] or equivalently char *.

   char* message = "Time to go home";

   char message[] = "Time to go home";

Assignment and concatenation operators are overloaded to allow use with string variables.

string type

This object type requires the <string> header.

   string s;
   s = s + " more";

Declarations

Simple variable declarations

Write the type, a variable name, an optional initial value, and a comment. It's possible to write a comma-separated list of variable names after the type or to omit the comment, but it's not a good style.

   int  t;               // temp in Celsius
   char separator = ','; // name separator
   unsigned short h;     // height in pixels

Constant declarations

Use the keyword const in front of a declaration which has an initial value. Constant names should be in uppercase characters. If the name has multiple words, they should be separated by underscore ("_").

   const int MAX_SIZE = 20; // Max number of keys.

Enumeration Types

A sequence of integer constants can be defined with enum.

enum Direction (NORTH, EAST, SOUTH, WEST);
// NORTH is 0, EAST is 1, ...
Direction myWay;