Perl -- Loop, foreach, if, unless, while

1. foreach

@array = qw(red orange blue green);

$count = 1;
foreach $color (@array)
{
     print "Color $count: $color \n";
    $count++;
}

@numbers = {1..10};

foreach $number (@numbers)
{
$number = $number + 10; //add 10 to $number
print "$number \n";
}

2. if

$number = 10;

if($number > 10)
{...}
elseif($number < 10)
{...}
else{...}

unless($number == 20)
{
 ...
}else{
 ...
}

3.

$number++; 后计算；
++$number; 先计算后赋值；

4.立方

$sum = 2 ** 3;

5. mod
$sum = 10 % 3;
the result is 1;

6.
use integer
$sum = 10 / 3;
print $sum;
the result is 3;

7. string equal use "eq" and number use "=="
if ($word eq "hel"){...}

not equal use "ne" and number use "!="

8. while


$count = 1;
while($count <= 10){
 ...
$count++;
}

9. until

$count = 0;
until(){

$count++;
}