Conditionals

Conditionals are expressions that evaluate to either true or false and determine what the program will do next. As programs become more complex, conditionals can make programs more flexible and robust by addressing multiple scenarios.

As we write more complex programs, conditionals allow us to address multiple scenarios and make our programs more robust.

An if statement executes a code block when its condition evaluates to true. If the condition is false, the code block does not execute.

var halloween = true

if halloween {
  print("Trick or treat!")
}

// Output: Trick or treat!

An else if statement provides additional conditions to check for within a standard if/else statement. else if statements can be chained and exist only after an if statement and before an else.

var weather = "rainy"

if weather == "sunny" {
  print("Grab some sunscreen")
} else if weather == "rainy" {
  print("Grab an umbrella")
} else if weather == "snowing" {
  print("Wear your snow boots")
} else {
  print("Invalid weather")
}

// Output: Grab an umbrella

An else statement is an optional partner to an if statement. When the condition for the if statement evaluates to false, the code within the body of the else will execute.

var turbulence = false

if turbulence {
  print("Please stay seated.")
} else {
  print("You may freely move around.")
}

// Output: You may freely move around.