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:

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# 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  

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Output:

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

Example 2:

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# 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

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Output:

You got A grade!

Important Points:

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

    Example:

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    # 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

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    Output:

    You order Ristretto!
    
  • You can also use case statement without any value.

    Example:

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    # 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

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    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:

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    # 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

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    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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