Comparison Methods

You’re getting good at this, so I’ll try to let the code do the talking. First, to see whether one object is greater than or less than another, we use the methods > and <:

No problem.

Likewise, we can find out whether an object is greater than or equal to another (or less than or equal to) with the methods >= and <=:

And finally, we can see whether two objects are equal using == (which means “Are these equal?”) and != (which means “Are these different?”). It’s important not to confuse = with ==. = is for telling a variable to point at an object (assignment), and == is for asking the question “Are these two objects equal?”

Of course, we can compare strings, too. When strings get compared, Ruby compares their lexicographical ordering, which basically means the order they appear in a dictionary. For example, cat comes before dog in the dictionary, so we have this:

This has a catch, though. The way computers usually do things, they order capital letters as coming before lowercase letters. (That’s how they store the letters in fonts—for example, all the capital letters first and then the lowercase ones.) This means it will think 'Xander' comes before 'bug lady'. So if you want to figure out which word would come first in a real dictionary, make sure to use downcase (or upcase or capitalize) on both words before you try to compare them.

Similarly surprising is this:

OK, 2 is less than 10, so no problem. But that last one?! Well, the '1' character comes before the '2' character—remember, in a string those are just characters. The '0' character after the '1' doesn’t make the '1' any larger.

One last note before we move on: the comparison methods aren’t giving us the strings 'true' and 'false'; they are giving us the special objects true and false that represent…well, truth and falsity. (Of course, true.to_s gives us the string 'true', which is why puts printed true.) true and false are used all the time in a language construct called branching.