Swift - Literals

A literal is the source code representation of a value of an integer, floating-point number, or string type. The following are examples of literals −

42                // Integer literal
3.14159           // Floating-point literal
"Hello, world!"   // String literal

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.

Here are some examples of integer literals −

let decimalInteger = 17         // 17 in decimal notation
let binaryInteger = 0b10001     // 17 in binary notation
let octalInteger = 0o21         // 17 in octal notation
let hexadecimalInteger = 0x11   // 17 in hexadecimal notation

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.

Here are some examples of floating-point literals −

let decimalDouble = 12.1875
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 −

The following example shows how to use a few string literals −

let stringL = "Hello\tWorld\n\nHello\'Swift 4\'"
print(stringL)

When we run the above program using playground, we get the following result −

Hello World

Hello'Swift 4'

There are three Boolean literals and they are part of standard Swift 4 keywords −

• A value of true representing true.
• A value of false representing false.
• A value of nil representing no value.