Perl Tips
Split last field but one using delimeter / :
($start,$finish) = split(/\//,$fields[-2]);
Chop off last character:
$finishx = substr($finish,0,-1);
Chop off first character:
$startx = substr($start,1);
Accepting command line arguments:
These are stored in array @ARGV , $ARGV[0] is the first argument, $ARGV [1] the second, etc.
To find out the number of command line arguments:
$#ARGV + 1 - $#ARGV is the number of the last argument. e.g. if it's $ARGV[7], $#ARGV will equal 7 so adding one gives the number of arguments (remembering that the first argument will be $ARGV[0})
To find the number of elements in an array
scaler @array
To find the last element of an array
$array[-1]
To check if an array is empty
if (!@array)
To check if $ variable has a value
if (defined $value)
String sort
@result = sort {$a cmp $b } @somelist;
Numeric sort
@result = sort {$a <=> $b } @somelist;
Numeric sort, reverse order
@result = sort {$b <=> $a } @somelist;
Reverse numeric sort of a hash
@result = sort { $hash{$b} <=> $hash{$a} } keys(%somehash);
Break out of a loop
last;
Exit that iteration of a loop and start next iteration
next;
Go back to the start of a loop iteration
redo;
comparision operators
numeric | string | |
---|---|---|
equal | == | eq |
not equal | != | ne |
less than | < | lt |
more than | > | gt |
less than or equal | <= | le |
greater than or equal | => | eq |
Perl Modules
To check which perl modules are installed
instmodsh -l
For easy cpan module install cpan App::cpanminus . You can then install modules as follows:
cpanm Module::Name
This will work out th dependencies, do the build, etc. To upgrade do cpanm –self-upgrade
For Windows
- perl Makefile.PL
- dmake
- dmake test
- dmake install
More useful Perl tips here: http://wiki.preshweb.co.uk/doku.php
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