Ruby | Case Statement - GeeksforGeeks

26 Oct, 2018
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 inputstr = "two"  # using case statementcase str   # using whenwhen "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 statementcase 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' statementcase 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!"endOutput:You order Ristretto!

Example:
# Ruby program to illustrate # how to use multiple values # in when statement  choice = "5"  # using 'case' statementcase 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 valuecase          # 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'endOutput:String contains letters
Example:
# Ruby program to illustrate no # value in case statement  str = "GeeksforGeeks"  # here case statement # has no valuecase          # 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 callputs 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'endOutput: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.
Example:
# Ruby program to illustrate case # statement in a method call  str = "1234"  # here case statement # has no value & used as # in puts method callputs 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.
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