Ruby defined operator

Last update on August 19 2022 21:50:52 (UTC/GMT +8 hours)

defined? operator

The defined? the operator is used to check whether or not the passed expression is defined. It returns nil if its argument is not defined, otherwise, it returns a descriptive string of that argument.

Syntax :

defined? expression

Here are some usage of defined? operator:

Example: Ruby defined operator

x =  1
Height = 100
puts ("defined operator in Ruby")
puts defined? x               # "local-variable"
puts defined? 12              # "expression"
puts defined? y               # nil
puts defined? puts            # "method"
puts defined? Height          # "constant"
puts defined? $&              # nil
puts defined? $_              # "global-variable"
puts defined? Math::PI        # "constant"
puts defined?( c = 22 )       # "assignment"
puts defined? 12.abs          # "method"

Output:

defined operator in Ruby
local-variable
expression

method
constant

global-variable
constant
assignment
method

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