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Editorial Team
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Asked: 2026-06-07T06:58:44+00:00

How can I turn an array of elements into uppercase? Expected output would be:

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How can I turn an array of elements into uppercase? Expected output would be:

["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]  
=> ["MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY"]

The following didn’t work and left them as lower case.

Day.weekday.map(&:name).each {|the_day| the_day.upcase }
 => ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
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1 Answer

  1. Editorial Team

    Return a New Array

    If you want to return an uppercased array, use #map:

    array = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]

# Return the uppercased version.
array.map(&:upcase)
=> ["MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY"]

# Return the original, unmodified array.
array
=> ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]

    As you can see, the original array is not modified, but you can use the uppercased return value from #map anywhere you can use an expression.

    Update Array in Place

    If you want to uppercase the array in-place, use #map! instead:

    array = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
array.map!(&:upcase)
array
=> ["MONDAY", "TUESDAY", "WEDNESDAY", "THURSDAY", "FRIDAY"]
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