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# Constants and Literals

Posted On : 03 Jun 2016
Updated On : 03 Jun 2016
Total Views : 1504

A constant is a value or an identifier whose value cannot be change during program execution. In other words, you can say variable is fixed value.

For example: 1, 2.5, "C programming is easy" etc.

`Value of variable are called literals.`

``` const double PI = 3.14
```

Here, PI is a constant. Basically what it means is that, PI and 3.14 is same for this program.

### Integer constants

A integer constant is a numeric constant (associated with number) without any fractional or exponential part.

There are mainly three types of integer constants available in C programming

1. decimal constant(base 10) : 0, -7, 8 etc.

2. octal constant(base 8) : 031, 066, 044 etc.

3. hexadecimal constant(base 16) - 0x4f, 0x5a, 0x321 etc.

In C programming, octal constant starts with a 0 and hexadecimal constant starts with a 0x.

### Floating-point constants

A floating point constant is a numeric constant that has either a fractional form or an exponent form. For example

### Character constants

A character constant use in single quotes. For example: `'a', 'l', 'm', 'F'`

## Escape Sequences

Sometimes, it is necessary to use characters which cannot be typed or has special meaning in C programming. For example: newline(enter), tab, question mark etc. In order to use these characters, escape sequence is used.

For example: \n is used for newline. The backslash ( \ ) causes "escape" from the normal way the characters are interpreted by the compiler.

List of Backslash Character Constants in C
Constant
Meaning
a
b
Back Space
f
Form Feed
n
New Line
r
Carriage Return
t
Horizontal Tab
v
Vertical Tab
"'"
Single Quote
'"'
Double Quote
‘?’
Question Mark
‘\’
Backslash
‘\0’
Null

### String constants

String constants are the constants which are enclosed in a pair of double-quote marks

Constant
Meaning
"Great"
String constant
""
Null String Constant
" "
String constant of Five white space
""
Null String Constant
"Coding is Rhyme\n"
prints string with newline

### Enumeration constants

Keyword enum is used to define enumeration types that means user can define their own data type. For example:

```enum subject {C, Html, Java, Sql};
```

Here, subject is name of variable and C, Html, Java and Sql are the values (enumeration) constants having value 0, 1, 2 and 3 accordingly.

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