Conditional Statements
A conditional statement tests whether a statement is true
or false
and performs logic based on the answer. Both true
and false
are pseudovariables—you can’t assign values to them. The former is an object of TrueClass
, and the latter is an object of FalseClass
.
The if Statement
These statements begin with if
and close with end
:
if
x == ythen
puts "x equals y"end if
x != y:
puts "x is not equal to y"end if
x > y puts "x is greater than y"end
The separator then
(or its synonym :) is optional unless the statement is on one line.
Negation
The negation operator !
reverses the true
/false
value of its expression:
if!
x == y then puts "x does not equal y" end if!
x > y puts "x is not greater than y" end
Multiple tests
Combine multiple tests in an if
statement using &&
and ||
, or their synonyms and
and or
, which have lower precedence:
ruby = "nifty" programming = "fun" if ruby == "nifty" && programming == "fun" puts "Keep programming!" end if a == 10 && b == 27 && c == 43 && d == −14 print sum = a + b + c + d end if ruby=="nifty" and programming=="fun" and weather=="nice" puts "Stop programming and go outside for a break!" end if a == 10 || b == 27 || c = 43 || d = −14 print sum = a + b + c + d end if ruby == "nifty" or programming == "fun" puts "Keep programming!" end
Statement modifier for if
You can also use if
as a statement modifier by placing the if
at the end of the statement:
puts "x is less than y" if
x < y
The else statement
Add an optional else
to execute a statement ...
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