Ruby: array is being passed by reference into function? -

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• is ruby pass reference or value? 11 answers

i have simple code below

    def testarray       arr_tree = [1,2,3,4,5]       (1..3).each |index|         abcde(arr_tree)         puts arr_tree[0]       end     end      def abcde(node_tree)       node_tree[0] += 100     end 

so inside testarray function, have array arr_tree being passed function abcde. change value of array inside abcde function , print array inside testarray changed value here. output is

101 201 301 

but expecting

1 1 1 

please explain why results this? how can achieve expected result?

everything "passed object" in ruby.

and arrays objects.

if want avoid side-effects make copy of argument

def abcde(node_tree)   copy = node_tree.dup   copy[0] += 100   copy end 

a note of caution though since named variable tree, dup method makes shallow copy only. shallow means array copied not elements.

why did not "pass reference" above?

"pass reference" concept language , not make sense in context of ruby. technically native implementation of ruby uses pass value, value pointer object structure. thinking of ruby using "pass value" misleading since not create copy of data structures before passed function. seems assumed happen…