Ruby conditionals
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The document discusses Ruby conditionals including if/else statements, case statements, and unless statements. If/else statements allow executing code conditionally based on boolean expressions. Case statements allow executing different code blocks based on the value of a variable. Unless statements provide a way to check if a condition is false.
Ruby conditionals
- 1. Conditionals
- 2. TruthTruth: Everything is true except for:false nilTherefore0 is true“” is true
- 3. Conditionals: ifif age > 17 puts “can vote”endif age > 17 puts “can vote”else puts “attends school”endStatement Modifiers:do_something if x == 4Other Syntax:if x == 4 then do_something end
- 4. Conditionals: ifif age >= 21 puts “can drink”elsif age > 17 puts “can vote”else puts “too young”end
- 5. Checking for falseif !(name == “superman”) …if not (name == “superman”) …
- 6. Unless“unless” provides us with another way of checking if a condition is false: unless human status = "superhero" end status = "superhero" unless human
- 7. Casecase superherowhen "superman" city = "metropolis"when "batman" city = "gotham_city"else city = "central_city"end
- 8. Case Refactoringcity = case superherowhen "superman" "metropolis"when "batman" "gotham_city"else "central_city"end
- 9. Casecase numwhen 1puts "one"when 2..5puts "that is small"else puts "pretty big"end
- 10. Casecase namewhen "Sarah"puts "awesome"when /Mr.*/puts "formal guy"else puts "whatever"end
- 11. Casecase args when String puts "Got a String" when Array puts "Got an Array” when Hash puts "Got a Hash"end
Editor's Notes
- #3: Unlike some languages with the 0 and empty string! Binds more tightly than than the “not” keyword so you do need parentheses for example 1, but don’t need parentheses for example 2
- #4: Conditionals are key to being able to make decisions in a programleft looks like every other languageparentheses are optional in ruby make sure to do ==, = is an assignment, == is a conditional testExplain putsright is a little different…people in ruby don’t like to type…english readableA statement modifier lets you move control structures at the end of an expression.
- #5: Conditionals are key to being able to make decisions in a programleft looks like every other languageparentheses are optional in ruby make sure to do ==, = is an assignment, == is a conditional testExplain putsright is a little different…people in ruby don’t like to type…english readableA statement modifier lets you move control structures at the end of an expression.
- #7: Unless can be awkward, especially with else. Usually you’ll want to use if for conditionals with else clauses.Occasionally unless is more readable:unless something is nil