programming-for-dummies

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Branching Statements
Branching Statements
The simplest branching statement is an IF statement that runs only one or
more commands if a Boolean condition is True, such as
if condition
Command
end
If you write the entire IF statement on a single line, you must make sure you
include the then keyword, such as
if condition then Command end
Ruby also includes a negated form of the IF statement called the UNLESS
statement that looks like this:
unless condition
Command
end
The UNLESS statement runs only if the condition is False.
a = 5
unless a < 1
puts “This will print out.”
end
Because the condition a < 1 is False, the preceding UNLESS statement
runs the command sandwiched between the UNLESS keyword and the END
keyword.
Both the IF and UNLESS statements can make the computer choose between
two mutually exclusive sets of commands by including an ELSE keyword,
such as
if condition
Command1
else
Command2
end
Although the IF-ELSE statement can only give the computer a choice of two
groups of commands to run, the IF-ELSIF statement can offer the computer
multiple groups of commands to run, such as
if condition1
Command
elseif condition2