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Ruby Basics

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Inspecting Values

2:12 with Jay McGavren

Sometimes calling "puts" with a Ruby value doesn't reveal everything about it. This is why Ruby provides a method named "p" in addition to "puts" and "print". The "p" method allows us to inspect the values we pass to it, to print them out approximately the same way they would appear in Ruby code.

  • Sometimes calling puts with a Ruby value doesn't reveal everything about it.
  • These calls to puts appear to output nothing at all, even though we're passing Ruby objects to each one.
    • A string with nothing but space characters
    • An empty string
    • The special value nil and an empty array, important concepts that we'll discuss in future courses
    • All appear empty.
puts "     "
puts ""
puts nil
puts []

Output:

This is why Ruby provides a method named p in addition to puts and print. The p method allows us to inspect the values we pass to it, to print them out approximately the same way they would appear in Ruby code.

p "     "
p ""
p nil
p []

Output:

"     "
""
nil
[]

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    We're trying to print the user's entry with the string, 0:00
    You entered #{answer} widgets here at the end of our widgets.rb code. 0:03
    But for some reason, 0:08
    a new line is appearing in the middle of that string in the output. 0:09
    Let's try adding puts answer to take a look at the contents of the answer 0:13
    variable to see if we can figure this out. 0:17
    We'll go down to our console and try running it. 0:20
    And if we enter 8, we see here at the end that it prints 8. 0:24
    We don't really see anything unexpected there, but sometimes calling 0:27
    puts with a Ruby variable doesn't reveal everything about it. 0:32
    These calls to puts appear to output nothing at all, 0:36
    even though we're passing Ruby objects to each one. 0:39
    We have a string that contains nothing but space characters, 0:42
    an empty string, the special value nil, and an empty an array, 0:45
    which are both important concepts that we'll discuss in future courses. 0:49
    All of them appear empty in the output. 0:53
    It's for situations like this that Ruby provides a method named p 0:56
    in addition to puts and print. 1:00
    The p method allows us to inspect the values we pass to it, 1:02
    to print them out approximately the same way they would appear in Ruby code. 1:06
    So let's try replacing all these calls to puts with calls to just p. 1:10
    Save that and try running it. 1:15
    And now we can see that we have a string with five spaces that we passed to p. 1:18
    An empty string. 1:24
    The value nil. 1:25
    And an empty array. 1:28
    We can tell that these apparently empty values aren't actually empty at all. 1:30
    Let's close out of this and go back to our widget store program and 1:34
    try inspecting the value in our answer variable. 1:38
    Instead of passing answer to puts, we'll pass it to the p method. 1:41
    Now let's try running this. 1:46
    ruby widgets.rb. 1:48
    Enter the number of widgets we want. 1:51
    And here in the output, we can see our answer, which was passed to the p method. 1:54
    And here at the end, we can see \n at the end of the string. 1:59
    What is that \n? 2:04
    It must have something to do with the output skipping to the next line. 2:06
    We'll learn the answer in the next video. 2:09

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