This document discusses data types in C++. It describes the three main categories of data types: primitive/fundamental types like int and char, derived types which are based on primitive types, and user-defined types created with structures. It also covers data type modifiers, constants/literals of different data types, and rules for declaring variables in C++ like their scope and naming conventions.

1. Datatype in C++
•Data type is a keyword used to identify type of data.
•It is used for storing the input of the program into
the main memory (RAM) of the computer by
allocating sufficient amount of memory space in the
main memory of the computer.
•In general every programming language is containing
three categories of data types. They are
1. Fundamental or primitive data types
2. Derived data types
3. User defined data types

3. Primitive data types
These are the data types whose variable can hold
maximum one value at a time, in C++ language it
can be achieve by int, float, double, char.

5. Derived data types
1. These data type are derived from fundamental
data type.
2. Variables of derived data type allow us to store
multiple values of same type in one variable but
never allows to store multiple values of different
types.

6. User defined data types
1. User defined data types related variables allows us
to store multiple values either of same type or
different type or both.
2. This is a data type whose variable can hold more
than one value of dissimilar type, in C++ language
it is achieved by structure.

7. Data type modifiers
• The data type modifiers are listed here:
1. signed
2. unsigned
3. long
4. Short
• The modifiers signed, unsigned,
long, and short can be applied to integer base
types.
• In addition, signed and unsignedcan be applied to
char, and long can be applied to double.

10. Constants/Literals
• Constants refer to fixed values that the program may
not alter and they are called literals.
• Constants can be of any of the basic data types and can
be divided into Integer Numerals, Floating-Point
Numerals, Characters, Strings and Boolean Values.
C++ allows several kinds of literal
1. Integer literals
2. Floating-point literals
3. Boolean literals
4. Character literals
5. String literals

11. Integer Constants
• An integer literal can be a decimal, octal, or
hexadecimal constant.
• A prefix specifies the base or radix: 0x or 0X for
hexadecimal, 0 for octal, and nothing for decimal.
• An integer literal can also have a suffix that is a
combination of U and L, for unsigned and long,
respectively.

12. Floating-point Constants
• A floating-point literal has an integer part, a decimal
point, a fractional part, and an exponent part.

13. Boolean Constants
• There are two Boolean literals and they are part of
standard C++ keywords:
1. A value of true representing true.
2. A value of false representing false.
• You should not consider the value of true equal to 1
and value of false equal to 0.

14. Character Constants
• Character literals are enclosed in single quotes.

15. String Constants
• String literals are enclosed in double quotes.
• A string contains characters that are similar to
character literals: plain characters, escape
sequences, and universal characters.

16. The const Keyword

17. Variable Declaration Rule in C++
• To Declare any variable in C++ you need to follow rules and
regulation of C++ Language, which is given below;
• Every variable name should start with alphabets or
underscore (_).
• No spaces are allowed in variable declaration.
• Except underscore (_) no special symbol are allowed in the
middle of the variable declaration.
• Maximum length of variable is 8 characters depend on
compiler and operation system.
• Every variable name always should exist in the left hand side
of assignment operator.
• No keyword should access variable name.
Syntax:
Datatype variable_name;
int a;

18. Scope of Variable in C++
• In C++ language, a variable can be either of global
or local scope.
Global variable
1. Global variables are defined outside of all the
functions, generally on top of the program.
2. The global variables will hold their value
throughout the life-time of your program.
Local variable
1. A local variable is declared within the body of a
function or a block.
2. Local variable only use within the function or block
where it is declare.