2 Slides Conditionals Iterators Blocks Hashes Arrays


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  • 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.
  • 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
  • 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
  • Alot of the time you will be using an array when you iterate over somethingAn array is just a list of items.Every spot in the list acts like a variable and you can make each spot point to a different objectW means wordsArray is a class, needs to start with capital letter
  • IRBif you go off the array it will be nil
  • join is cool because it makes a string for youshovel operatormultidimensional array
  • Does anyone know what a hash is? associative array collection of key-value pairskeys can be numbers or strings Difference from an Array
  • merge takes the value from the second hashmerge! changes h1
  • you would think that delete should need a bang to change the hash, but delete doesn’t exist with a bangdelete returns the value
  • 5 is an object that is an instance of the integer classtimes is a method of the 5 objecttimes is a method on an object that is an instance of integer
  • it does the block of code three timesit is very rare that you will see a while loop in ruby...you can do the loops we did earlier, but rubyists will mock you.
  • What is a block? It is the ability to take a block of code, wrap it up in an object and pass it to a method. Then you can run the block of code within the method any time you want…sometimes twice! The result is kind of like sending a method to a method, except that a block isn’t bound to an object like a method is – it is an object. So what? Why use blocks?elegant syntax for iteratorsBecause there are some things that only blocks can do, like being passed to a method and being returned by a method.
  • two ways to declare a blockuse curly brackets for single lines of codeuse do end for multi lines of code
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