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Home/ Questions/Q 74117
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Asked: May 10, 20262026-05-10T20:18:29+00:00 2026-05-10T20:18:29+00:00

How can I check whether a variable is defined in Ruby? Is there an

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How can I check whether a variable is defined in Ruby? Is there an isset-type method available?

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  1. 2026-05-10T20:18:29+00:00Added an answer on May 10, 2026 at 8:18 pm

    Use the defined? keyword (documentation). It will return a String with the kind of the item, or nil if it doesn’t exist.

    >> a = 1  => 1 >> defined? a  => 'local-variable' >> defined? b  => nil >> defined? nil  => 'nil' >> defined? String  => 'constant' >> defined? 1  => 'expression' 

    As skalee commented: ‘It is worth noting that variable which is set to nil is initialized.’

    >> n = nil   >> defined? n  => 'local-variable' 
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