Methods

Front 1

Write two methods, one that returns the string "Hello" and one that returns the string "World". Then print both strings using #puts, combining them into one sentence.

Back 1

To do anything with the methods, we first have to define them. We've chosen to define our methods as hello and world. We've written both methods to only do one thing: return a string. This makes it easy for us to print the desired strings simply by calling the methods with #puts.

Front 2

Write a method named greet that invokes the following methods:

When greet is invoked with #puts, it should output the following: Hello World

Make sure you add a space between "Hello" and "World", however, you're not allowed to modify hello or world.

Back 2

In the previous exercise, we invoked hello and world using string interpolation and printed their values with #puts. In this exercise, however, we're extracting that combination and placing it in a method named greet. We invoke both methods as we did before, but this time we don't use string interpolation. We simply invoke the methods and use the + sign to combine their values. If we do hello + world, and don't account for an extra space, the output will look like this:

That's not very readable so it'd be good to add a space between the two words. To do that, we place a string containing one space between the method invocations.

Front 3

Using the following code, write a method called car that takes two arguments and prints a string containing the values of both arguments

Expected output: Toyota Corolla

Back 3

When writing the car method it's important to keep two things in mind. First, make sure you're allowing for the correct number of parameters. If the method invocation provides two arguments, then the method must be able to accept two arguments and vice versa. Second, when printing the string, you should use #puts from inside the method. In this exercise, the method invocation isn't prepended by #puts, therefore, to print the string you have to print it from within the method.

Further Exploration

Remove the #puts call from the car method. Modify your program so it still prints the result.How do the return values of car differ with and without the #puts?

Front 4

The variable below will be randomly assigned as true or false. Write a method named time_of_day that, given a boolean as an argument, prints "It's daytime!" if the boolean is true and "It's nighttime!" if it's false. Pass daylight into the method as the argument to determine whether it's day or night.

Back 4

Our time_of_day method is simple enough. It accepts one argument, daylight, and proceeds to use that argument as an ifconditional. If daylight evaluates to true, then "It's daytime!" will be printed. If it evaluates to false, then "It's nighttime!" will be printed. Also, notice that we use #puts within the if/else statement and not when we invoke the method.

Front 5

Fix the following code so that the names are printed as expected.

Back 5

When running the original code, you should have gotten an error called ArgumentError that looks like this:wrong number of arguments (given 1, expected 0) (ArgumentError)This error is telling you that dog passed in an argument when it was invoked. However, dog doesn't accept any arguments. To fix this, we need to change dog so that it accepts one argument.After fixing the error and running the code again, you should encounter the same type of error. It should look like this:wrong number of arguments (given 0, expected 1) (ArgumentError)This error is nearly identical to the first one, except it's reversed. Here, cat accepts one argument. However, no arguments were passed in when cat was invoked. To fix this, we need to add an argument when we invoke the method, like this: cat('Ginger').When you're writing methods, it's important to keep track of how many arguments the method accepts and how many it's given upon invocation. Both numbers need to match or an error will be thrown.

Front 6

Write a method that accepts one argument, but doesn't require it. The parameter should default to the string "Bob" if no argument is given. The method's return value should be the value of the argument.

The code should output true twice.

Back 6

The method assign_name is written the same as any other method except for one key difference: it has a default parameter. This means that it accepts one argument, but doesn't break if that argument isn't given. It will simply assign the parameter to the default value which, in this case, is "Bob".

Front 7

Write the following methods so that each output is true.

Back 7

The goal here is to write two methods, add and multiply, that do simple math operations. We use the + and * operators inside the methods to add or multiply the numbers then we return the results. By returning the results, we can use the addmethod as an argument for multiply just like we would with a variable.

Front 8

The variables below are both assigned to arrays. The first one, names, contains a list of names. The second one, activities, contains a list of activities. Write the methods name and activity so that they each take the appropriate array and return a random value from it. Then write the method sentence that combines both values into a sentence and returns it from the method.

Back 8

The Array#sample method will select a random element from an array and return it.

Both methods, name and activity, are simple enough. We chose to use Array#sample to grab a random value from the array and return it from the method. Then, we pass those methods as arguments into sentence which lets us use the return value however we want. In this case, we want to combine them into a sentence. Notice that we aren't printing the string from within the method, instead, we're returning it so that it can be printed outside the method.

Front 9

Write a method named print_me that prints "I'm printing within the method!" when invoked.

print_me

Back 9

In previous exercises we've used #puts both inside and outside methods. When you use #puts inside a method, you're outputting one thing and returning another. #puts outputs whatever it's given and returns nil. In this case, we're printing the value inside the method, which means the method's return value is nil.

Front 10

Write a method named print_me that returns "I'm printing the return value!" when using the following code.

puts print_me

Back 10

When you don't use #puts within the method or when you invoke the method, then nothing will be printed. This doesn't mean that there's nothing available to print though. Methods will always return something. In this case, print_me is returning the string "I'm printing the return value!". Therefore, to print that string, all we need to do is place #puts before the method invocation.