A variable refers to a storage location in the computer’s memory that one can set aside to save, retrieve, and manipulate data.

var score = 0

Constants refer to fixed values that a program may not alter during its execution. One can be declared by using the `let`

keyword.

let pi = 3.14

Swift supports arithmetic operators for:

`+`

addition`-`

subtraction`*`

multiplication`/`

division`%`

remainder

var x = 0x = 4 + 2 // x is now 6x = 4 - 2 // x is now 2x = 4 * 2 // x is now 8x = 4 / 2 // x is now 2x = 4 % 2 // x is now 0

Type annotation can be used during declaration.

The basic data types are:

`Int`

: integer numbers`Double`

: floating-point numbers`String`

: a sequence of characters`Bool`

: truth values

var age: Int = 28var price: Double = 8.99var message: String = "good nite"var lateToWork: Bool = true

String interpolation can be used to construct a `String`

from a mix of variables, constants, and others by including their values inside a string literal.

var apples = 6print("I have \(apples) apples!")// Prints: I have 6 apples!

Compound assignment operators provide a shorthand method for updating the value of a variable:

`+=`

add and assign the sum`-=`

subtract and assign the difference`*=`

multiply and assign the product`/=`

divide and assign the quotient`%=`

divide and assign the remainder

var numberOfDogs = 100numberOfDogs += 1print("There are \(numberOfDogs) dalmations!")// Prints: There are 101 dalmations!