strings_and_conditionals.swift

import Cocoa

//contants do not vary
let a = "Hello, playground"
//a = "Hello, world" // error: reassignment to constant 'a'



//variables can vary
var anotherA = "Hello, Pedro"
anotherA += "!"
print(anotherA)  // Hello, Pedro!

var numberOfStoplights = 3
numberOfStoplights += 1 // numberOfStoplights = 4



//String interpolation
var population: Int
population = 9_000_000
let townName = "San Francisco"
let elevation = 12

var townDescription = "\(townName) has a population of \(population) with \(numberOfStoplights) stoplights."
townDescription += " It is located at an elevation of \(elevation) feet."
print(townDescription) // San Francisco has a population of 9000000 with 4 stoplights. It is located at an elevation of 12 feet.




//Conditional statements

//big or small
let population2: Int = 42200
var message : String
let hasPostOffice: Bool = true

if population2 < 10000 {
    message = "Small"
} else {
    message = "Big"
}

/*
This could be written using the ternary operator.
*/
message = population2 < 10000 ? "Small" : "Big"

if population2 < 10000 {
    message = "\(townName) is a Small town!"
} else if population2 >= 10000 && population2 < 50000 {
    message = "\(townName) is a Medium town!"
} else {
    message = "\(townName) is a Big town!"
}


print(message) // Small

if !hasPostOffice {
    print("Where do we buy stamps?¿") //never prints
}