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in reply to My very confusing questions

if no array is given then it uses the default @_
Inside a subroutine, shift and pop operate on @_, but in the main body of a program, they operate on @ARGV, which is what you generally want.

Update: Removed unshift and push as they are different. My mistake.

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Re^2: My very confusing questions
by Random_Walk (Prior) on Jul 09, 2014 at 14:52 UTC

    Surely parameterless shift and pop, operate on @ARGV in the main, or @_ in a sub, as described. But unshift and push, unseasoned with parameters, are a syntax error.

    /usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;print join 
+"<>", @ARGV;'
that<>more
/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;push;print 
+join "<>", @ARGV;'
Not enough arguments for push at -e line 1, near "push;"
/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;unshift;pri
+nt join "<>", @ARGV;'
Not enough arguments for unshift at -e line 1, near "unshift;"
/usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;push "X";pr
+int join "<>", @ARGV;'
Type of arg 1 to push must be array (not constant item) at -e line 1, 
+near ""X";"
 /usr/bin/perl -le '@ARGV=qw(this that more less);pop;shift;unshift "X
+";print join "<>", @ARGV;'
Type of arg 1 to unshift must be array (not constant item) at -e line 
+1, near ""X";"

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    R.

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