PHP Array to CSV

Instead of writing out values consider using fputcsv().

This may solve your problem immediately.

Note from comment: I should mention that this will be making a file on your server, so you'll need to read that file's contents before outputting it, also if you don't want to save a copy then you'll need to ùnlink`the file when you are done

This is a simple solution that exports an array to csv string:

function array2csv($data, $delimiter = ',', $enclosure = '"', $escape_char = "\\")
{
    $f = fopen('php://memory', 'r+');
    foreach ($data as $item) {
        fputcsv($f, $item, $delimiter, $enclosure, $escape_char);
    }
    rewind($f);
    return stream_get_contents($f);
}

$list = array (
    array('aaa', 'bbb', 'ccc', 'dddd'),
    array('123', '456', '789'),
    array('"aaa"', '"bbb"')
);
var_dump(array2csv($list));

Reference