- implode: documentation ( source)
- str_replace: documentation ( source)
<?php
$rows = [
['a', 'b"and"c'],
['d', 'e,\'f']
];
$line = '';
foreach ($rows as $row) {
$line .= '"' . implode('","', str_replace('"', '""', $row)) . '"' . "\r\n";
}
echo $line;