A literal is the representation of
a value of an integer, floating-point number, or string type.
The below are examples of literals.
Integer
Literal
42
Floating-point
literal
2.34354646
String
Literal
"Hello
world"
Integer Literals
An integer literal can be a
decimal, binary, octal, or hexadecimal constant. Binary literals begin with 0b,
octal literals begin with 0o, and hexadecimal literals begin with 0x and
nothing for decimal.
Examples:
let
decimalInteger = 18
let
binaryInteger = 0b10001
let
octalInteger = 0o21
let
hexadecimalInteger = 0x11
Floating-point Literals
A floating-point literal has an
integer part, a decimal point, a fractional part, and an exponent part. You can
represent floating point literals either in decimal form or hexadecimal form.
Decimal floating-point literals
consist of a sequence of decimal digits followed by either a decimal fraction,
a decimal exponent, or both.
Hexadecimal floating-point literals
consist of a 0x prefix, followed by an optional hexadecimal fraction, followed
by a hexadecimal exponent.
Example:
let
decimalDouble = 15.1457
let
exponentDouble = 1.21875e1
let
hexadecimalDouble = 0xC.3p0
String Literals
A string literal is a sequence of
characters surrounded by double quotes, with the following form
"characters"
String literals cannot contain an
unescaped double quote ("), an unescaped backslash (\), a carriage return,
or a line feed. Special characters can be included in string literals using the
following escape sequences –
Escape sequence
|
Meaning
|
\0
|
Null Character
|
\\
|
\character
|
\b
|
Backspace
|
\f
|
Form feed
|
\n
|
Newline
|
\r
|
Carriage return
|
\t
|
Horizontal tab
|
\v
|
Vertical tab
|
\'
|
Single Quote
|
\"
|
Double Quote
|
\000
|
Octal number of one to three
digits
|
\xhh...
|
Hexadecimal number of one or more
digits
|
The following example shows how to
use a few string literals
import Cocoa
let stringL = "Hello\tWorld\n\nHello\'Swift\'"
println(stringL)
Result:
Hello World
Hello'Swift'
Boolean Literals
There are three Boolean literals
and they are part of standard Swift keywords
• A value of true representing true.
• A value of false representing false.
A value of nil representing
no value.
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