# 2.2 Comparison Operators

``````x == y    Equal to
x != y    Not equal to
x > y     Greater than
x >= y    Greater than or equal to
x < y     Less than
x <= y    Less than or equal to
x === y   Two objects are equal
x !== y   Two objects are not equal
``````
• comparison operators return `true`/`false` and can be stored as a Bool
• must Type Cast to a common type (ie. all Ints, Doubles…)
``````let x = 100, y = 200

// -> true
let b1 = x < y
// -> false
let b2 = x == y

// -> true
(1, "zebra") < (2, "apple")
// -> true
(3, "apple") < (3, "bird")
// -> true
(4, "dog") >= (4, "dog")
``````

## Ternary Conditional Operator

`Question ? <true value> : <false value>`

• returns one of two values based on if the question is true or false
``````let pop = 5000
let pop2 = 2000

// -> 2000
let minimum = pop < pop2 ? pop : pop2
// -> small town
let message = pop < 9999 ? "small town" : "\(pop) is big!"
// -> true
pop >= 5000 ? "We're good" : "Oops, not quite"
``````

## Nil-Coalescing Operator `??`

• use when a variable might have a value or be nil
• if no value, then use a default value
``````var personalSite: String?
let defaultSite = "http://www.lyfebug.com"

// without ?? operator
let website: String
if personalSite != nil {
website = personalSite!
} else {
website = defaultSite
}

// with ?? operator
let website2 = personalSite ?? defaultSite
``````

## Identity Operators `===`

• used to determine if two vars/cons refer to the same instance of a class
• `===` → identical
• `!==` → not identical to
``````class C {
var varX = 1
}

let classOne = C()
let classTwo = C()
let classThree = classOne

// -> might be equal…
if classOne === classTwo {
print("Identical")
} else {
print("Maybe equal, but not identical")
}

// -> Yes
if classOne === classThree {
print("Yes, they refer to the same object.")
}
``````