Chapter 2: Types, Operators, and Expressions

Declarations #

Variables #

Variables in C are defined by providing a type then the variable's name:

int my_variable;

Define #

A #define declaration indicates a value that will be replaced during preprocessing.

#define PI 3.14

Constants #

Variables can also be prefixed with a const keyword to indicate that the object will not change/be re-assigned to something else.

const float PI = 3.14;

Enums #

Enums provide a list of constant integer values (unless specified otherwise).

enum boolean { NO, YES };
enum months { JAN = 1, FEB = 2, MAR = 3, APR = 4, /** etc. */ };
enum likes { FRUIT = "apple", HOBBY = "reading" };

Data Types and Sizes #

These primitive data types may also be prefixed with short (at least 2-bytes) or long (at least 4-bytes) where short must never be greater than or equal to long.

int and char can also be prefixed with signed or unsigned.

Constants #

Constants are raw values that can be assigned to variables and/or operated on to produce new values.

/**
 * Integer constants
 **/
1234
1234L  // Long
1234UL // Unsigned Long

/**
 * Floating-point constants.
 * NOTE: That floating-point constants use `double` unless suffixed with `f/F`.
 */
123.4
123.4f // Float
123.4L // Long Double
1e-2
01234  // Octal
0x1F   // Hexadecimal

/**
 * Character/string constants
 **/
'x'
'\n'            // Escape character
"Hello, world!" // String
'\o12'          // Byte-character
'\x1F'          // Hex-character
'\0'            // Null-character

Operators #

Arithmetic #

Logical #

Bitwise #