如何填充数组中的字符串？

Question

I'm trying to fill in a string in an array value that has a empty '' do I need to use isset or empty to check it first?

Here is my code

echo table();

function table() {
    $a = array  ('0' => array('Jan de Boer', '213','440'),
                 '1' => array('Gerda Severin','214','442'),
                 '2' => array('Jean Dubois','215',''),
                 '3' => array('Peter Geringh','221','449'),
                 '4' => array('ricardo','666','666'));

    echo "<table border='6px'>
    <tr><th colspan='3'>Alle werknemers</th></tr>
    <tr><th>Naam</th>
    <th>kamer</th>
    <th >Toestelnummer</th></tr>";

    for ($x=0;$x<5;$x++){
        echo "<tr>";
        for($y=0;$y<3;$y++){
            echo "<td>",$a[$x][$y].'</td>';
        }
        echo "</tr>";
    }
    echo "</table>";
}

It needs to fill in the blank '' like a string unknown.

Answer 1

Perform a check if the string is blank and replace with a value, in my example 'UNKNOWN'

    echo table();
function table()

{    
$a = array  ('0' => array('Jan de Boer', '213','440'),
             '1' => array('Gerda Severin','214','442'),
             '2' => array('Jean Dubois','215',''),
             '3' => array('Peter Geringh','221','449'),
             '4' => array('ricardo','666','666'));

echo "<table border='6px'>
<tr><th colspan='3'>Alle werknemers</th></tr>
<tr><th>Naam</th>
<th>kamer</th>
<th >Toestelnummer</th></tr>";

    for ($x=0;$x<5;$x++){
    echo "<tr>";
    for($y=0;$y<3;$y++){
    if($a[$x][$y] == "") $a[$x][$y] = 'UNKNOWN';
        echo "<td>",$a[$x][$y].'</td>';
    }
    echo "</tr>";
}

echo "</table>";

}