Learn to Code with Ruby

In this lesson, we'll learn more about the puts method, which outputs text to the Terminal/output when the program runs. The puts method adds a line break to the end of the output. Like other methods in Ruby, it can be invoked with and without parentheses. We can also use commas to output multiple elements with the put method; Ruby will separate each one with a line break.

In this lesson, we'll introduce escape characters, which are special symbols we can use in a Ruby string. Escape characters add special effects like line breaks, tabs, and  symbols/characters to a string. We escape the expected pattern of output, which is Ruby outputting the literal characters that we've typed.

In this lesson, we introduce the print method, another way to output text to the screen. The print method is similar to puts but it does not add a line break to the end of the output.

In this lesson, we learn about the p method, which outputs a "technical" version of the object/output. For example, the p method will print a string with double quotes around the content. It exists primarily for the benefit of developers.

In this lesson, we'll learn how to use comments to ask Ruby to ignore specific lines of code. We create a comment with a hashtag/octothorpe (#) symbol. We can place the hashtag at the beginning of a line or after a line of valid Ruby code. Comments enable developers to leave explanations, metadata, annotations, diagrams, jokes, and more in their program.

In this lesson, you'll how to create multiline comments using =begin and =end. Ruby will treat any content between the two keywords as part of the comment.

In this lesson, we'll discuss the differences between integers and floating-point numbers and their syntax in Ruby.

In this lesson, we'll learn the symbols for mathematical operations including addition, subtraction, multiplication, division, and modulo.

In this lesson, we'll learn how to concatenate (join) two strings together using the + operator.

In this lesson, we'll learn about errors/exceptions in Ruby including TypeError, which Ruby raises when we provide an invalid type of object for an operation.

Review everything we learned in this section of the course including output methods, comments, exceptions, concatenation, and more.

In this lesson, we'll learn about variables. A variable is a name we assign to a value in our program that is subject to change over time.

In this lesson, we practice declaring various variables in a .rb file and using them in expressions throughout the program. The variable syntax declaration begins a name, then an equal sign, and the value/object to assign that name to.

See the solution to the previous coding challenge.

In this lesson, we'll learn about the NameError exception, which Ruby raises when it cannot recognize a name in your program.

In this lesson, we'll learn how to declare multiple variables and provide initial values to them on a single line.

In this lesson, we'll learn how to swap two variables (invert the values they store).

In this lesson, we'll learn several shortcuts to perform an operation on a variable's value and assign the result back to the original variable.

In this lesson, we'll learn to declare constants in Ruby. A constant is a name for a value that will not change over the program's execution.

Review everything we've learned in this course section including variables, constants, parallel variable assignment, and more!

Welcome to the next section of the course! In this lesson, we begin our exploration of methods on various Ruby objects. A method is a message we can send to an object. A method produces a return value, which represents the final output of the method.

Learn about some methods on Ruby's Integer object including next, succ, and pred.

See the solution to the previous coding challenge.

Learn about the NoMethodError exception, which Ruby raises when we invoke a method that does not exist on an object.

Method chaining is a sequence of successive method invocations. Each invocation returns an object upon which we invoke the next method in line.

The inspect method converts an object to a string representation for debugging. The inspect method is available on all Ruby objects. Ruby’s p method invokes the inspect method on an object behind the scenes.

Learn about nil, a special Ruby object that represents nothingness, blankness, or the absence of a value.

String interpolation is the process of injecting content into a string. That content can be anything from a variable to a Ruby expression. Within a string's double quotes, write a hashtag followed by curly braces. Write the variable or operation within the braces.

In this lesson, we’ll learn about the gets method, which collects input from the user. Like puts or p, gets is a top-level method. We also discuss how to use the chomp method to chop off the newline character from the end of a string.

Practice using the class method, which is available on any Ruby object and returns the class from which the object is made. The class is a blueprint for an object. Another way to think about the class is like the template or schematic. It is the abstract foundation from which a concrete object is created. We call the object an instance of a class.

In this lesson, we’ll learn how to use methods like to_i, to_f, and to_s to convert an object from one type to another (to strings, to floats, to integers, etc).

Review the concepts introduced in this course section including object methods, the nil object, the gets method, the class method, conversion methods, and more.

In this lesson, we'll learn about a new object type called a Boolean, which represents either true or false

In this lesson, we'll explore the equality operator ( == ), which tests whether two objects are equal.

In this lesson, we use the inequality operator ( != ) to test whether two objects are NOT equal.

In this lesson, we'll learn various mathematical symbols available in Ruby including <, <=, >, and >= for greater-than/less-than logic.

In this lesson, we'll introduce predicate methods, which are methods that return a Boolean. These methods always end with a question mark.

In this lesson, we'll learn how to pass an argument to a method. An argument is an input we pass to a method that customizes how the method will run.

In this lesson, we'll practice passing multiple arguments to a method with the between? method. The between? method validates whether a number falls between a range.

In this lesson, we'll dive behind the scenes to see how Ruby translates numeric symbols like + into equivalent method calls on objects.

In this lesson, we'll learn about exclusive methods on Float objects including floor and ceil.

Review the concepts we've learned in this section including Booleans, predicate methods, equality and inequality operators, new object methods, and more.

In this lesson, we'll introduce the syntax for declaring a method in Ruby. A method is a reusable procedure that encapsulates a piece of logic; the intent is to capture the logic once and then reuse the method throughout the program.

In this lesson, we'll cover how to define a method with a parameter and utilize the parameter in the method body. We then invoke the method and pass in sample arguments.

In this lesson, we'll define a method with multiple parameters and pass in multiple arguments for its invocation.

Our method's arguments are regular Ruby objects so we are able to perform operations on them (such as invoking methods). In this lesson, we practice working with string and integer arguments to a custom method.

A local variable is a variable declared in a method body. Local variables only exist as long as the method executes. In this lesson, we practice declaring local variables and discuss the idea of scope, the boundary/confines within which a name exists in your program.

In this lesson, we'll learn how to declare a return value within our method. A return value is the final output of a method, the final product it creates for the outside world. Every Ruby method has a return value.

All Ruby methods must return a value. If we do not provide a specific value, a method will return nil by default. Ruby will return the last evaluated expression as the method’s return value. Thus, we can skip the return keyword and write our return value on the last line of the method. This is considered best practice in the Ruby community.

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Provide a default argument to a parameter, a fallback value to use when the invocation does not provide one.

See the solution to the previous lesson's coding challenge.

In this lesson, we'll review the concepts introduced in this section of the course including:

• Methods

• Parameters and arguments

• Return values

• Local variables and scope

• Optional parameters and default arguments

Welcome to the next section of the course! In this section, we'll focus on blocks in Ruby. A block is a chunk of code that is associated with a method invocation. In this lesson, we introduce the concept in combination with the times method, which repeats a chunk of code a specified number of times.

See the solution to the previous lesson's coding challenge.

In this lesson, we'll learn how to use vertical pipes to accept block variables in our blocks. A block variable is a dynamic value that exists only as long as the block does. It is a way for a method to pass data to the block.

See the solution to the previous lesson's coding challenge.

In this lesson, we'll learn two more methods, upto and downto, which move from a starter integer to an end integer in steps of 1.

In this lesson, we'll learn about the step, which iterates from one numeric value to another in steps/intervals. The method will enable us to practice more with blocks in Ruby.

In this lesson, we'll review the concepts introduced in this section of the course including:

• Adding a block to a method

• Single-line and multi-line block declaration

• Differences between blocks and arguments

• The times, upto, downto, and step methods

Welcome to the Conditions section of the course. In this lesson, we'll learn about the if statement, which enables us to run a section of Ruby code if a condition is met. Conditionals enable our programs to have branching logic.

In this lesson, we'll learn how to combine predicate methods with if statements. The two are a perfect duo because an if statement expects a Boolean and a predicate method returns a Boolean.

In this lesson, we'll introduces the concepts of truthiness and falsiness. A truthy value is one that is good enough to be true in a Boolean context; a falsy value is one that is good enough to be false in a Boolean context. false and nil are the two falsy values in Ruby; all other objects/values are truthy.

See the solution to the previous lesson's coding challenge.

In this lesson, we'll learn how add an elsif statement to check for another condition after an if. Ruby will execute the section of code belonging to the first condition that evaluates to true.

In this lesson, we'll introduce the else keyword, which allows us to guarantee the execution of code if no if condition or elsif condition is previously met.

See the solution to the previous lesson's coding challenge.

In this lesson, we employ the AND operator (&&) to check for multiple conditions in an if statement.

In this lesson, we continue our exploration of multiple conditions with the OR operator (||), which checks if either one of multiple conditions is true.

See the solution to the previous lesson's coding challenges.

In this lesson, we'll practice adding parentheses when using && and || operators to establish the precedence for evaluating a condition. Precedence refers to the order of importance.

In this lesson, we'll see how to nest an if statement inside another if statement to create a more complex logical path. All of these constructs are independent Ruby building blocks that we are free to couple together in our code.

In this lesson, we'll learn how to consolidate a simple if/else construct with the ternary operator. The ternary operator has a condition ? true value : false value code structure.

In this lesson, we'll invoke one method from the body of another. This structure allows us to split up the complexity of business logic across several smaller methods.

The case statement is a shortcut that enables us to replace longwinded if/elsif/else statements with a single construct. In this lesson, we use a case statement in a method to offer a review of various food items.

The unless keyword creates "execute if false" condition for a piece of code. Ruby will execute a section of code unless a condition is met. In this lesson, we showcase the keyword alongside a classic if statement.

We can replace 1-line if and unless statements with shorter statement modifiers. We put the evaluation logic in front of the respective keywords; the end keyword is not required.

The conditional assignment operator assigns a value to a variable if it's current value is nil. We use this design when there is an expensive computation that we only want to run once and preserve for later use in a variable.

In this lesson, we'll review the concepts introduced in this section of the course including:

• The if, elsif, and else keywords to create conditional branches of logic

• Multiple conditions with the && and || operators

• Using parentheses to establish precedence (order of importance)

• Declaring the ternary operator as a shortcut to an if/else statement

• Cleaning up multiple if/elsif statements with the case/when syntax.

• The unless keyword for running a section of code when a condition evaluates to false.

• Using the conditional assignment operator to assign a value to a nil variable

Ruby allows us to use single quotes for string declarations. Single-quote strings do not allow string interpolation. They also do not escape characters like \n.

A multi-line string is officially called a here document or here doc in Ruby. Multi-line strings begin with a << symbol. Afterwards, we place an identifier that marks the start of the multi-line string. Ruby includes all content after the identifier in the string, including tabs and new lines.

In this lesson, we review the equality (==) and inequality (!=) operators. We also introduce the < and > symbols to test whether a string comes before or after another in alphabetical order.

The concat method concatenates two strings to together. Call the concat method on a string and pass it an argument of the second string We can pass only one argument (i.e. one string) to the concat method. The method mutates the original string.

The prepend method is another concatenation method. It prepends (the opposite of appends) the argument to the beginning of the string

The length method returns the number of characters in the string. Spaces count! The size method is identical to the length method.

The object returned back is a Integer object. As a result, Integer instance methods are available on the object.

See the solution to the previous lesson's coding challenge.

• Ruby assigns an index position to every character in a string. The index starts counting from 0.

• Pass the index position within square brackets to extract a single character.

• Ruby returns nil if the index position does not exist.

See the solution to the previous lesson's coding challenge.

• Use square brackets to extract multiple characters from a string.

• The first argument is the starting index position. The second argument is the number of characters to pull out.

• Negative index positions are accepted for the first argument. For example, [-7, 5] means start 5 characters from the end and pull out 5 characters.

See the solution to the previous lesson's coding challenge.

• Ruby strings are mutable. We can add, remove, or update characters.

• Reference the character by index position, then use = to assign a new value.

• The insert method mutates a string by adding a character at a specified index position.

• The first argument is the index position, the second is the character(s) to add.

• The empty? method returns true if the string is empty. Remember, a space counts as a valid character.

• The nil? method is available on every Ruby object. The nil? method returns true if called on a nil object. Any valid string (including an empty string) will return false for the nil? method.

• The capitalize method returns a new string with an uppercase first letter.

• The upcase method returns a string with all letters in uppercase.

• The downcase method returns a string with all letters downcased.

• The swapcase method swaps lowercase and uppercase characters.

• Ruby ignores numbers and characters in any case methods.

• The reverse method reverses a string's character

• A bang method is a method with a side effect, usually a mutational one.

• A bang method modifies the original object that the variable is pointing to.

• Bang method names conclude with an exclamation point (!).

• Bang methods are an alternative to reassigning the return value of a method call to the same variable

Review the concepts introduced in this course section including:

• String comparisons and equality

• Index positions

• Character extraction

• Character casing methods

• The insert method

• The reverse method

• Bang methods

• and more!

A while loop repeats a piece of condition while a condition is met. The loop rechecks the condition before each round. In this lesson, we learn the syntax for declaring a while loop in Ruby.

• A while loop executes while a condition is true.

• An until loop executes until a condition is true. It essentially executes as long as the evalution condition is false.

• Tackle FizzBuzz, a popular coding challenge for beginners. FizzBuzz prints different conditional statements if a number is divisible by 3, 5, or both values.

Walk through a sample solution of the FizzBuzz problem from the previous lesson.

In this lesson, we’ll introduce the next keyword, which moves execution automatically to the next iteration of a loop. In other words, it finalizes the current iteration and restarts from the beginning of the loop.

• The break keyword forces the termination of a loop before its natural conclusion.

• Recursion is when a method calls itself.

• Recursions requires us to think in multiple levels/layers of execution.

• The base case is a terminating condition that forces the recursion to complete and "bubble up" back to the original caller.

In this lesson, we practice recursion by implementing both an iterative and recursive solution for reversing a string.

Review the concepts introduced int he last section of the course including:

• The while loop

• The until loop

• FizzBuzz

• The next keyword

• The break keyword

• Recurison

• and more!