Ruby | Case Statement

The case statement is a multiway branch statement just like a switch statement in other languages. It provides an easy way to forward execution to different parts of code based on the value of the expression.

There are 3 important keywords which are used in the case statement:

• case: It is similar to the switch keyword in another programming languages. It takes the variables that will be used by when keyword.
• when: It is similar to the case keyword in another programming languages. It is used to match a single condition. There can be multiple when statements into a single case statement.
• else: It is similar to the default keyword in another programming languages. It is optional and will execute when nothing matches.

Syntax:

case expression

when expression 1
  # your code

when expression 2
  # your code
.
.

else
  # your code
end

Flow Chart:

Example 1:

# Ruby program to illustrate the
# concept of case statement

#!/usr/bin/ruby

print "Input from one, two, three, four: "

# taking input from user
# str = gets.chomp

# hardcoded input
str = "two"

# using case statement
case str

# using when
when "one"
  puts 'Input is 1'

when "two"
  puts 'Input is 2'

when "three"
  puts 'Input is 3'

 when "four"
  puts 'Input is 4'

else
  puts "Default!"

end

Output:

Input from one, two, three, four: Input is 2

Example 2:

# Ruby program to illustrate
# case statement

#!/usr/bin/ruby

marks = 70

# marks is the input
# for case statement
case marks

# using range operators ..
when 0..32
  puts "You fail!"

when 33..40
  puts "You got C grade!"

when 41..60
  puts "You got B grade!"

else
 puts  "You got A grade!"

end

Output:

You got A grade!

Important Points:

• In case statement the when statement can contain multiple values and range(see above example).

  Example:

  # Ruby program to illustrate
  # how to use multiple values
  # in when statement
  
  choice = "5"
  
  # using 'case' statement
  case choice
  
      # here 'when' statement contains
      # the two values
      when "1","2"
          puts "You order Espresso!"
  
      when "3","4"
          puts "You order Short Macchiato!"
  
      when "5","6"
          puts "You order Ristretto!"
  
      when "7","8"
          puts "You order Cappuccino!"
  
  else
      "No Order!"
  end

  Output:

  You order Ristretto!
  

• You can also use case statement without any value.

  Example:

  # Ruby program to illustrate no
  # value in case statement
  
  str = "GeeksforGeeks"
  
  # here case statement
  # has no value
  case
  
      # using match keyword to check
      when str.match(/\d/)
            puts 'String contains numbers'
  
      when str.match(/[a-zA-Z]/)
            puts 'String contains letters'
  else
      puts 'String does not contain numbers & letters'
  end

  Output:

  String contains letters

• You can use case statement in method call. Like method call, a case statement will always return a single object.

  Example:

  # Ruby program to illustrate case
  # statement in a method call
  
  str = "1234"
  
  # here case statement
  # has no value & used as
  # in puts method call
  puts case
  
      # using match keyword to check
      when str.match(/\d/)
  
          'String contains numbers'
  
      when str.match(/[a-zA-Z]/)
  
          'String contains letters'
  else
  
      'String does not contain numbers & letters'
  end

  Output:

  String contains numbers
  

  Explanation: Here we are using the case statement in a puts method call. The benefit of doing this that we can omit the puts from the when statement.