Literals/constants are used to represent fixed values which can't be altered later in the code.

1. Integer literals

Interger literals are numeric literals. Below are the examples of various types of literals

79         // decimal (base 10) 
0253       // octal (base 8)
0x4F       // hexadecimal (base 16)
22         // int
53u        // unsigned int
79l        // long
7953ul       // unsigned long

2. Float point literals

Float point literals are also numeric literals but has either a fractional form or an exponent form.

79.22         // valid
79E-5L        // valid
53E          // not valid as it is incomplete exponent
.e22          // not valid as missing integer or fraction

3. Boolean literals

There are two Boolean literals which are part of standard C++ keywords −

• true value representing true.

• false value representing false

4. Character literals

Character literals are represented with in single quotes. For example, a, 1 etc. A character literal can be a simple character (e.g., 'a'), an escape sequence (e.g., '\n'), or a universal character (e.g., '\u02C0').

Escape sequence	Description
\n	New line
\r	Carriage Return
?	Question mark
\t	Horizontal tab
\v	Vertical tab
\f	Form feed
\	Backslash
'	Single quotation
"	Double quotation
\0	Null character
?	? Question mark
\b	Back space
\a	alert or bell

5. String literals

String literals are represented with in double quotes. String literals contains series of characters which can be plain characters, escape sequence or a universal character.

"Hello World"

How to define constants

You can use either #define or const to define constants as shown below.

• Using #define

#define identifier-name value

• Using Const

const datatype variable-name = value;