Working with Arrays (1)
Before you get started, make sure you have your text editor and terminal open,
and you have navigated to your exercises directory in the terminal. E.g. cd
~/ruby-for-beginners/exercises.
Exercise 3.1
Create a new, empty file. Save it as arrays_1-1.rb. Fill in the following
line:
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
# your code goes here
So that, when you run your code (run ruby arrays_1-1.rb), you get the
following output:
5
Exercise 3.2
Copy your file to a new file: cp arrays_1-1.rb arrays_1-2.rb, then open this
new file.
Add another line before the line that you just added, so that, when you run your code, you get the following output:
99
Exercise 3.3
Make a new file arrays_1-3.rb, and fill in the following line:
numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
# your code goes here
p numbers
So that you get the following output:
[2, 4, 6, 8, 10]
Read the documentation for the method select that you can use on arrays
on the Ruby documentation
Exercise 3.4
Again, copy your last file to a new file: cp arrays_1-3.rb arrays_1-4.rb,
then open this new file.
Now change the code that you just added so that you get the following output:
[10, 8, 6, 4, 2]
The method select that you used in the last exercise returns an array.
On this array (the return value) you can use another method, by, again, just
appending a dot . and the method name to it, i.e., to the end of the line.
There is another method that reverses the order of the array. You can find it by googling for “ruby array reverse”.
Exercise 3.5
Again, copy your last file to a new file: cp arrays_1-4.rb arrays_1-5.rb,
then open this new file.
Now change your code so that you get the following output:
[10, 8, 4, 2]
Bonus: Find at least three different solutions for this last change.