Learn to Code with Ruby

• Use the puts method to output or log text
• The puts method adds a line break to the end of the output

• Use the print method to output or log text
• The print method does not add a line break to the end of the output

• Use the p method to see a more literal output of a Ruby string or object
• This is equivalent to calling the .inspect method on an object

Review the concepts introduced so far in this section of the course.

• Assign multiple variables values at once
• Learn how to swap the values in two variables

• Declare constants, whose value should not change throughout the program

• Begin our exploration of methods on various Ruby objects. A method is simply a message sent to an object
• Start discussion of return values, the final output of a method

• Continue discussion of return values from objects
• Introduce the nil object which represents nothingness, blankness, or the absence of a value

• Utilize string interpolation to inject variables or calculations into a string
• Practice the interpolation syntax -- a hashtag followed by curly braces (#{})

• Use the gets method to collect input from the user
• Use the chomp method to chop off the newline from the end of a string
• Write a program to collect input from the user and print it out to them

Review the concepts introduced so far in this section of the course

• Call the .class method to return the class of the object, the blueprint from which it is built

• Utilize methods like to_s and to_s to convert numeric objects to strings and vice versa

• Learn about a new object type called a Boolean, which represents either true or false

• Explore predicate / Boolean methods available on objects which always return a true or false
• Call the odd? and even? methods on integer objects to see if they are odd or even

• Use the equality operator ( == ) to test whether two objects are equal

• Use the inequality operator ( != ) to test whether two objects are NOT equal

Review the concepts introduced so far in this section of the course.

• Use the < and > operators to compare whether one number is less than or greater than another
• Explore the related <= and >= operations to test less than / greater than or equal to

• Dive behind the scenes to see how Ruby processes basic arithmetic methods
• Begin a deep dive into arguments, which are inputs passed to a method call

• Continue exploration of parameters and arguments in more detail
• Call the between? predicate method to test whether a number falls in between two others

• Call some exclusive methods available on Float objects, which include a decimal component

• Use a popular programming shortcut to perform a mathematical operation on a variable and overwrite the variable's value

• Call the .upto and .downto methods on an integer to iterate from that number to another
• Further enhance our knowledge of blocks and block variables

• Call the .step method on an integer to iterate from that number to another at a frequent interval
• Further enhance our knowledge of blocks and block variables

Review the concepts introduced so far in this section of the course.

• Practice multiple syntactical options for creating a new String object.
• Call common methods like .length and .class on String objects.

• Use multiline strings to create strings that utilize more than one line.

• Use a special syntax to signify escape characters in string
• Escape characters have special meanings like line breaks, backslashes, or double quotes

• Learn the differences between using single vs. double quotes for creating strings.
• Double-quoted strings allow for interpolation and escape characters.

• Review the equality (==) and inequality (!=) operators
• Use the two operators on String objects

• Add / concatenate one string to another with concatenation operators / methods

• Call the .length or .size method to return the numbers of characters in the string
• See what happens when the methods are called on an empty string

• Use bracket syntax to extract a single character from a string

• Use bracket syntax with a few tweaks to extract multiple sequential characters from a string

• Introduce the Range object which represents an interval of numbers or characters
• Feed the range to the bracket syntax to extract sequential characters from a string

• Combine bracket syntax from previous lessons with the assignment operator (=) to mutate a string by assigning new characters

• Call the .downcase, .upcase, .capitalize, and .swapcase methods to modify the casing of a string
• The methods each return a new String object

• Call the .reverse method on a String to reverse the order of its characters

• Introduce bang methods, which mutate the original object the method is called on
• Bang methods are an alternative to reassigning the return value of a method call to the same variable

• Call the .include? predicate method to check if a certain substring is found in the string

• Call the .empty? predicate method to check if a string contains no characters
• Call the .nil? method which returns true only if called on a nil object

Review the concepts introduced so far in this section of the course.

• Define local variables within a method.
• Local variables disappear as soon as the method is done executing.

• Add one or more arguments to a method to allow for input when the method is invoked
• A parameter is the name for an expected method argument

• Return a value from a custom method
• Differentiate between an explicit and implicit method return

• Discover the default return value of a method
• Explore why nil is the return value of the puts method

• Use the if statement, our first conditional, to evaluate code only if a condition evaluates to true

• Explore the concept of truthiness and falsiness in Ruby.
• false and nil are falsy in Ruby.
• All other objects are truthy.

• Add an elsif statement to check for the truthiness of another condition.
• Structure the code to follow a more complex logical path

• Fallback on the else keyword to execute code if no if or elsif condition above is met

• Employ the AND operator (&&) to check for multiple conditions in an if or elsif statement

• Employ the OR operator (||) to check if either one of two or more conditions is true.

Review the concepts introduced so far in this section of the course.

• Add parentheses when using && and || operators to establish the precedence for evaluating a condition

• Nest an if statement inside another to create a more complex logical path

• Call the .respond_to? predicate method to test whether an object can respond to a specific method

• Consolidate a simple if / else design by replacing it with the terser ternary operator

• Provide default / optional parameters to methods that will activate if the arguments are not passed on a method call

• Invoke one method from the body of another
• Invoke a method from inside a string using interpolation syntax

• Replace longwinded if / elsif / else statements with the case statement

• Utilize the exclamation point (!) to negate the value of an object and convert it to a Boolean
• Use two exclamation points (!!) to return the Boolean representation of an object.

• Use the unless keyword to simulate an "execute if false" condition for a piece of code.

• Begin discussion of a loop, an iteration that is repeated a specified number of times
• Introduce the while keyword for looping while a condition is true

• Continue discussion of loops and iterations
• Introduce the until keyword for looping until a condition is true

• Tackle Fizzbuzz, a popular coding challenge for beginners

• Replace simple if and unless statements with shorter inline statements
• The end keyword is not required with this simplified format

• Assign a value to a variable only if it is currently set to nil.
• Explore the advantages of this approach in professional code.

Review the concepts introduced so far in this section of the course.

• Generate a Range object of alphabetic characters
• Explore the caveats of uppercase and lowercase character ranges

• Call the .size method on a Range object to see the size of its interval

• Use the .includes? predicate method to see if a value falls between a Range
• Use the === syntax to see if a value falls between a Range

• Explore the Ruby rand method to generate a random floating point number or integer
• Provide the method a Range argument to get a number in between the interval

Review the concepts introduced so far in this section of the course.

• Instantiate multiple arrays full of different data types.
• Nest one array within another.

• Utilize the %w syntax to easily generate an array of strings.
• Elements in the brackets are written without quotes or commas.

• Utilize the Array.new method to create a new array.
• Populate a new array with a consistent set of values.

• Use square bracket syntax to select an element from an array.
• The first array element will have an index position of 0.

• Call the .fetch method on an array to extract an element by index position.
• Compare the differences between square bracket syntax and .fetch

• Extract multiple array elements with square bracket syntax
• Choose a starting point and the number of elements to select

• Feed a Range object to square brackets to extract multiple array elements.
• Review the differences between an inclusive and exclusive range.

• Call the .values_at method on an array to extract non-sequential array elements.
• Extract an array element more than once.

• Call the .slice method as an alternative to using square bracket syntax for array element extraction.

• Extract one or more array elements with familiar [] or .slice syntax.
• Overwrite the array element(s) with the equal sign (the assignment operator).

• Call the .length, .size, or .count methods to return the number of elements in an array.
• An empty array will return 0.

• Call the .empty? method which returns true if the array has no elements
• Call the .nil? method which returns true if called on a nil object.

• Call the .first and .last elements on an array to return the first and last elements.
• Call the two methods with an optional numeric argument to return an array of results.

• Call the .push method to add an element to the end of an array.
• Use the shovel operator (<<) to accomplish the equivalent of the .push method
• Call the .insert method to insert an element in a specific index position.

• Call the .pop method to remove an element from the end of the array.
• The .pop method also returns the element itself.

• Call the .shift method to remove an element from the beginning of the array.
• Call the .unshift method to add an element to the beginning of the array.

• Use the equality (==) and inequality (!=) operators to compare two arrays

• Use the spaceship operator (<=>) to compare two arrays together.
• -1 will be returned if the array on the left is less than the one on the right.
• 0 will be returned if the two array are equal.
• 1 will be returned if the array on the left is greater than the one on the right.

• Call the .to_a method on a Range object to convert it to an array

• Call the .is_a? predicate method on a variety of objects to test whether they inherit functionality from a specific class.
• The method will return true for an object's class or any of the superclasses above it.

Review the concepts introduced so far in this section of the course.

• Use the ri program from the Command Line to retrieve documentation on a Ruby class or an instance method

• Review blocks, which are attachments to methods that modify how they function.
• Review the two syntax options for a block (curly braces and do end).

• Call the .each method on an array to iterate over its elements one by one
• Provide the .each method a block to specify what to do on each iteration

• Provide block variables to an .each method block to represent the current array element being iterated over.

• Nest an .each method call within another .each method.

• Utilize the for loop to iterate over an array.
• Compare the differences between for and the .each method.
• See why the .each method is strongly preferred.

• Call the .each_with_index method to iterate over an array while keeping track of the index position.
• Provide a second block variable to hold the place of each index position.

• Tackle a programming problem that involves the .each_with_index method on an array.

• Call the .map or .collect method to iterate over an array, apply an operation to each element, and return a new array of the resulting elements.
• Practice the method with another challenge.

• Use the while and until loops as an alternative approach to iterate over array elements.

• Use the break keyword to break out of loop if a condition is met on an iteration.

• Use the next keyword to continue to the next iteration of a loop if a condition is met.

• Call the .reverse method on an array to rotate it, to present its elements in the opposite order.

• Call the .sort method to sort the elements in an array.
• The results will be in ascending order if an array consists of numeric element.
• The results will be in alphabetical order if an array consists of strings.

• Call the .concat method on an array to merge it with another array.

• Call the .max method on an array to return its largest element.
• Call the .min method on an array to return its smallest element.

• Call the .include? predicate method on an array to test whether it includes a value.

• Call the .index or .last_index method on an array to return the index position of the first occurrence of the argument.
• The methods will return nil if the element does not exist.

• Call the .reject method on an array to return only those elements that do not fit the block condition.

• Place multiple variables on the left side of an assignment operator to unpack a multi-dimensional array and assign each nested element to a variable.

• Combine the functionalities of the .select and .reject methods in the .partition method, which returns a multidimensional array.

Review the concepts introduced so far in this section of the course.

• Iterate over a string's characters by calling the .split or .chars method and then the .each method on the result array.
• An alternative is the .each_char method on the string.

• Call the .join method on an array to combine each of its elements and separate each with a delimiter.

• Call the .count method on a string to return the number of times a substring appears in the string.

• Call the .index method to return the first index position where the substring is found.
• Call the .rindex method to return the last index position where the substring is found.
• Emulate the functionality of the .index method with our own custom method.

• Call the .insert method to insert a character or characters at a specified index position in a string.

• Call the .squeeze method to remove all characters that occur two or more times in sequence.

• Call the .clear method on a string to rid it of content and return an empty string.

• Call the .delete method to remove all occurrences of the substring characters from the original string.

Review the concepts introduced so far in this section of the course.