Pearl shift operator is a simple question

Question

What is the purpose of the following two lines of perl ??

my $host = shift || 'localhost';
my $port = shift || 200;

This should return localhost and port 10. What is the shift keyword

Answer 1

This piece of code is a way of providing default values ​​for $hostand $port. It is usually located at the beginning of a script or routine and takes values ​​from @ARGVand, @_respectively.

This should return localhost and port 10.

, || OR, , LHS , RHS . ( ): " , , ".

shift ARRAY ARRAY :

ARRAY , @_ @ARGV , eval STRING, BEGIN {}, INIT {}, CHECK {}, UNITCHECK {} END {} .

http://perldoc.perl.org/functions/shift.html

, , shift . shift , , .

Answer 2

@_, @ARGV ( , ) @_/@ARGV, localhost $host.

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Answer 3

, shift @ARGV @_ - , .

$host @ARGV ( @_, ) "localhost", .

Perl.

Answer 4

shift . , .

Answer 5

If you use shift, always put an array on it. I have seen Perl programmers forget that outside the routine shiftworks on @ARGV. The more things a programmer must remember at the same time, the greater the likelihood that he will make a mistake.