Basic Operators

Comparison Operators

We can compare two tuples if they have same type and same number of values.

For example:

// true because 1 is less than 2; "zebra" and "apple" aren't compared
(1, "zebra") < (2, "apple")   

// true because 3 is equal to 3, and "apple" is less than "bird"
(3, "apple") < (3, "bird")    

// true because 4 is equal to 4, and "dog" is equal to "dog"
(4, "dog") == (4, "dog")      

Tuples can be compared with given operator only if the operator can be applied to each value in the respective tuples.

For example:

// OK, evaluates to true
("blue", -1) < ("purple", 1)       

// Error because < can't compare Boolean values
("blue", false) < ("purple", true) 

Range Operators

Closed Range Operator

(a…b) –>(a<=x<=b)

1. means a range runs from a to b
2. Including a and b
3. b must be grater than a

for index in 1...5 {
    print("\(index)")
}
// 1
// 2
// 3
// 4
// 5

Half-Open Range Operator

(a..<b) -> (a<=x<b)

1. means a range runs from a to b
2. Including a, but not including b
3. b must be grater than a

let names = ["Anna", "Alex", "Brian", "Jack"]
let count = names.count
for i in 0..<count {
    print("Person \(i + 1) is called \(names[i])")
}
// Person 1 is called Anna
// Person 2 is called Alex
// Person 3 is called Brian
// Person 4 is called Jack

One-Sided Ranges

An alternative writing for range operators.

(...5) -> (0<=x<=5)

(..<5) -> (0<=x<5)

let names = ["Anna", "Alex", "Brian", "Jack"]
for name in names[2...] { //means 2<=x<=count
    print(name)
}
// Brian
// Jack

for name in names[...2] { //means 0<=x<=2
    print(name)
}
// Anna
// Alex
// Brian

// we can handle range value as a object
let range = ...5
range.contains(7)   // false
range.contains(4)   // true
range.contains(-1)  // true

let’s think!