What is variable

Variable

Variable is a container that reserve memory from RAM according to its data type to store value. There are many types of variables. Variable must have:-

• Name
• Data type
• Size
• Value

Variable declaration in C++

Syntax of variable declaration is below

Data-type variable-name = value that variable hold;

int number;

Variable initialization in C++

int number = 12;

Here int is data-type, number is name of variable, 12 is the value this variable hold and its size is 4 bytes as size of int data-type is 4 bytes.

Variable data-types (Types of Variables) and sizes

Size of a variable may be different depending on the compiler and the computer you are using. Common data types and size are given below:-

Type	size
char	1 byte
int	4 bytes
short	2 bytes
float	4 bytes
double	8 bytes
string	8 bytes
boolean	1 byte

Write a C++ Program to check size of any data-types. For this C++ library provides us a function sizeof(data-type) to check size of all data types.

Data type size

Output:

Data type size output

Declare multiple variables in one line

Multiple variable can be declared in single line as below

int a, b, c, d;

Declare and initialize multiple variables in one line

Multiple variable can be declared and initialized in single line as below

int a=12, b, c=4, d=12;

C++ Program to declare and initialize all data types and display output 

Output: