function oin($glue, $arr) {
    $res = '';
    $add = false;
    foreach ($arr as $b) {
	if ($add) $res .= $glue;
	if (!$add) $add = true;
	$res .= $b;
    }

    return $res;
}

print oin(', ', array('a', 'b', 'c'));

$num = 5;
$array1 = array(1, 3, 5, 7, 9, 11, 13, 15, 17);
$array2 = array(2, 4, 6, 8, 10);

$big = array_merge($array1, $array2);
sort($big);
$one = array_slice($big, 0, 5);
$two = array_slice($big, 5);

print_r($one);
print_r($two);

$arr = array(3 => 'a', 5 => 'b', 9 => 'c');

#foreach
$vals = array_keys($arr);
for ($i=0; $i<count($vals); $i++) {
    print $vals[$i].' => '.$arr[$vals[$i]]."\n";
}

print preg_match('#0$#', '1543230')?'yes':'no';

ob_start();
$time1 = microtime(1);

for ($j = 0; $j < 10000; $j++) {
    for($i=0;$i<10;$i++)
    { echo '1php '; }
}

$a = (microtime(1)-$time1);

$time1 = microtime(1);

for ($j = 0; $j < 10000; $j++) {
while($i<10) {
echo 'w1';
$i +=1;
}
}

$b = (microtime(1)-$time1);
ob_end_clean();

echo "A: $a, B: $b";

$a = 10; 
$b = 515; 
$c = 0.515; 
$d = $b<=$a&&$a==$c||$b>$c?0:1; 
echo $d;

$d = 0&&0 || 1?0:1; у || приоритет меньше, чем у &&
$d = 0 || 0
$d = 0