That is doubly confusing code ...

2 effects are overlaying.

• the @arr inside the sub is the same like outside, because you didn't use my again. (Change the name and strict will throw an error, otherwise the function is a closure)
• the elements of @_ are aliases of the elements passed, i.e. the values of @arr (like demonstrated by Tobyink)

Since you reassign these elements with the map, you are effectively changing @_, it's like writing @_ = map { 2 * $_ } @_;

Change this to my @arr = map { 2 * $_ } @_; and your problem disappears

Style tips how to avoid this

it's always a good strategy to choose meaningful names for variables instead of arr or array , like this strict would have caught the error.

don't declare variables on top of your program if you only intend to use them much later.

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}

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In reply to Re: How come @_ gets changed here? by LanX
in thread How come @_ gets changed here? by pritesh_ugrankar

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