array kosong

<?php
if ($_POST) {
    $chk1 = $_POST['chkabc1'];
    $chk2 = $_POST['chkabc2'];
    $chk3 = $_POST['chkabc3'];
    for ($i = 0; $i < count($chk1); $i++) {
        echo "Checkbox 1 value ".$chk1[$i]."<br>";
        echo "Checkbox 2 value ".$chk2[$i]."<br>";
        echo "Checkbox 3 value ".$chk3[$i]."<br>";
     }
}


 ?>


 <!DOCTYPE html>
 <html>
 <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title></title>
    <link rel="stylesheet" href="">
 </head>
 <body>
    <form action="http://localhost/coba/arraykosong.php" method="POST" >
        <input type="checkbox" name="chkabc1[]" value="11">
        <input type="checkbox" name="chkabc1[]" value="12">
        <input type="checkbox" name="chkabc1[]" value="13">
        <input type="checkbox" name="chkabc1[]" value="14">
<br>
        <input type="checkbox" name="chkabc2[]" value="21">
        <input type="checkbox" name="chkabc2[]" value="22">
        <input type="checkbox" name="chkabc2[]" value="23">
        <input type="checkbox" name="chkabc2[]" value="24">
<br>

        <input type="checkbox" name="chkabc3[]" value="31">
        <input type="checkbox" name="chkabc3[]" value="32">
        <input type="checkbox" name="chkabc3[]" value="33">
        <input type="checkbox" name="chkabc3[]" value="34">
<br>
        <button type="submit">submit</button>
    </form>
 </body>
 </html>