All programming languages have a notion of truth built into them. Given two expressions, the computer can discern whether or not they are equivalent to each other.
In addition to numbers and text, Ruby has two special values,
true
and false
. These values are used when the computer
is asked to compare two expressions.
Try the following in an irb
session to get a sense of how
we make comparisons. Pay special attention to the double-equal
operator ==
which is used to compare two expessions against
each other.
Remember, comparisons use the
==
operator, not the single=
assignment operator.
irb(main)> 1 == 1
=> true
irb(main)> 1 < 2
=> true
irb(main)> 2 > 1
=> false
irb(main)> "hello" == "hello"
=> true
irb(main)> "hello" == "Hello"
=> false
irb(main)> "goodbye".upcase == "GOODBYE"
=> true
We will talk more about the concept of truth in section 3.