4: Variables, and keyword in c++ language

Variables, and keyword in c++ language

C++ Variable:

A variable is a name of the memory location. It is used to store data. Its value can be changed and it can be reused many times.
It is a way to represent memory location through symbol so that it can be easily identified.

syntax to declare a variable:

type variable_list;

Rules for defining variables

1. A variable can have alphabets, digits, and underscore.
2. A variable name can start with the alphabet and underscore only. It can't start with the digit.
3. No whitespace is allowed within the variable name.
4. A variable name must not be any reserved word or keyword e.g. char, float etc

Types	Data Types
Basic Data Type	int, char, float, double, etc
Derived Data Type	array, pointer, etc
Enumeration Data Type	enum
User Defined Data Type	structure

Basic Data Types

Data Types	Memory Size	Range
char	1 byte	-128 to 127
signed char	1 byte	-128 to 127
unsigned char	1 byte	0 to 127
short	2 byte	-32,768 to 32,767
signed short	2 byte	-32,768 to 32,767
unsigned short	2 byte	0 to 32,767
int	2 byte	-32,768 to 32,767
signed int	2 byte	-32,768 to 32,767
unsigned int	2 byte	0 to 32,767
short int	2 byte	-32,768 to 32,767
signed short int	2 byte	-32,768 to 32,767
unsigned short int	2 byte	0 to 32,767
long int	4 byte
signed long int	4 byte
unsigned long int	4 byte
float	4 byte
double	8 byte
long double	10 byte