CODEWITHSUNDEEP
rubyif-statementstatements
Elias Andersen
Elias Andersen

Reputation: 29

What's the major difference between if statements and unless statements?

I am new to programming and I don't understand what the difference is. I am coding in Ruby.

Upvotes: 2

Views: 620

Answers (3)

Vitalii Elenhaupt
Vitalii Elenhaupt

Reputation: 7326

One of the goals of Ruby language is to become more closer to the real English. And keywords if and unless are really good examples of that. Look at this:

if animal.can_speak?
  animal.say 'Woof!'
end

# moreover, it can be transformed in one-line, which looks pretty awesome:
animal.say 'Woof!' if animal.can_speak?

unless is an opposite of the if and instead of writing:

if not animal.can_speak?
  puts "This animal can't speak"
end

we can use unless, that usually considered as more natural way:

unless animal.can_speak?
  puts "This animal can't speak"
end

# it also has one-line approach:
puts "..." unless animal.can_speak?

Upvotes: 0

pangpang
pangpang

Reputation: 8821

unless is equal to if not

for example:

a= false

unless a
  puts "hello"
end

=> hello

if not a
  puts "hello"
end

=> hello

Upvotes: 0

duffymo
duffymo

Reputation: 308733

if should be obvious: execute a block of code if the condition is true.

unless is the opposite: execute a block of code if the condition is false.

http://www.codecademy.com/glossary/ruby/if-unless-elsif-and-else

Upvotes: 1

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