循环语句 #

my $count = 1;

while ($count <= 5) {
    print "Count: $count\n";
    $count++;
}

open my $fh, "<", "file.txt" or die $!;

while (my $line = <$fh>) {
    chomp $line;
    print $line . "\n";
}

close $fh;

while (1) {
    print "Running...\n";
    last;
}

my $count = 0;
print $count++, "\n" while $count < 5;

my $count = 1;

until ($count > 5) {
    print "Count: $count\n";
    $count++;
}

while (!($count > 5)) {
    print "Count: $count\n";
    $count++;
}

my $done = 0;
do_something() until $done;

for (my $i = 1; $i <= 5; $i++) {
    print "i = $i\n";
}

for (my $i = 5; $i >= 1; $i--) {
    print "i = $i\n";
}

for (my $i = 0; $i <= 10; $i += 2) {
    print "i = $i\n";
}

for (my ($i, $j) = (1, 10); $i <= $j; $i++, $j--) {
    print "i=$i, j=$j\n";
}

my @colors = ("red", "green", "blue");

foreach my $color (@colors) {
    print $color . "\n";
}

my @colors = ("red", "green", "blue");

foreach (@colors) {
    print $_ . "\n";
}

foreach my $i (1..10) {
    print $i . "\n";
}

my @numbers = (1, 2, 3, 4, 5);

foreach my $num (@numbers) {
    $num *= 2;
}

print "@numbers\n";

for my $item (@array) { }
foreach my $item (@array) { }

my @numbers = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

foreach my $num (@numbers) {
    last if $num > 5;
    print $num . "\n";
}

my @numbers = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

foreach my $num (@numbers) {
    next if $num % 2 == 0;
    print $num . "\n";
}

my $count = 0;

while ($count < 5) {
    $count++;
    print "Count: $count\n";
    redo if $count == 3;
}

OUTER: for my $i (1..3) {
    INNER: for my $j (1..3) {
        if ($i == 2 && $j == 2) {
            last OUTER;
        }
        print "i=$i, j=$j\n";
    }
}

my $count = 0;

while ($count < 5) {
    $count++;
    next if $count == 3;
    print "Count: $count\n";
}
continue {
    print "  (iteration done)\n";
}

print "Enter lines (Ctrl+D to end):\n";

while (my $line = <STDIN>) {
    chomp $line;
    last if $line eq "quit";
    print "You entered: $line\n";
}

my %person = (
    name => "Tom",
    age  => 25,
    city => "Beijing",
);

while (my ($key, $value) = each %person) {
    print "$key: $value\n";
}

{
    print "Processing...\n";
    last if done();
    redo;
}

while (1) {
    my $input = get_input();
    last if $input eq "exit";
    process($input);
}

my @squares = map { $_ ** 2 } 1..10;
my @evens = grep { $_ % 2 == 0 } 1..20;

for my $i (1..3) {
    for my $j (1..3) {
        print "($i, $j) ";
    }
    print "\n";
}

OUTER: for my $i (1..3) {
    for my $j (1..3) {
        if ($i + $j == 4) {
            next OUTER;
        }
        print "($i, $j) ";
    }
    print "\n";
}

#!/usr/bin/perl
use strict;
use warnings;
use v5.10;

for my $i (1..9) {
    for my $j (1..$i) {
        printf "%d×%d=%-4d", $j, $i, $i * $j;
    }
    print "\n";
}

#!/usr/bin/perl
use strict;
use warnings;
use v5.10;

my $target = int(rand(100)) + 1;
my $attempts = 0;

say "Guess a number between 1 and 100!";

while (1) {
    print "Your guess: ";
    my $guess = <STDIN>;
    chomp $guess;
    $attempts++;

    if ($guess < $target) {
        say "Too low!";
    } elsif ($guess > $target) {
        say "Too high!";
    } else {
        say "Correct! You got it in $attempts attempts!";
        last;
    }
}

#!/usr/bin/perl
use strict;
use warnings;
use v5.10;

my $file = "data.txt";

open my $fh, "<", $file or die "Cannot open $file: $!";

my ($line_count, $word_count, $char_count) = (0, 0, 0);

while (my $line = <$fh>) {
    $line_count++;
    $char_count += length($line);
    my @words = split /\s+/, $line;
    $word_count += scalar @words;
}

close $fh;

say "Lines: $line_count";
say "Words: $word_count";
say "Characters: $char_count";

#!/usr/bin/perl
use strict;
use warnings;
use v5.10;

my @data = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

my @evens = grep { $_ % 2 == 0 } @data;
my @squares = map { $_ ** 2 } @evens;
my $sum = 0;
$sum += $_ foreach @squares;

say "Original: @data";
say "Evens: @evens";
say "Squares of evens: @squares";
say "Sum of squares: $sum";