Quick Reference

Data Type

Loop

# for loop-index                
for(my $i = 0; $i < 10; $i++) { }

# for-each loop
my @total = ("is","a","string.");
foreach my $element (@total) { }

# while loop
my %hash = ( "k1" => "v1", "k2" => "v3", "k3" => "v3");
while(($key,$value)=each %hash) { }

System interaction

# count the parameters passed
my $total = scalar(@ARGV);

# show the parameters, start from 0, the first parameter, not file name
for(my $i = 0; $i < scalar(@ARGV); $i++) { }

Function

# declear function
sub getNum {
    my ($getString, $getOption) = @_;
    return 1;
}

# use function
my $getRes = getNum("input",1);

List

Dictionary

File I/O

# Read file
open(fin,"data.txt") or die("Error: File input error.\n");
foreach my $line (<fin>) { }
close(fin);

# Write file
open(fout,"> data.out") or die("Error: File output error.\n");
print fout $i."\n";
close(fout);