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    <h3>Editing: Base64Encoder.php</h3>
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/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Mime\Encoder;

/**
 * @author Chris Corbyn
 */
class Base64Encoder implements EncoderInterface
{
    /**
     * Takes an unencoded string and produces a Base64 encoded string from it.
     *
     * Base64 encoded strings have a maximum line length of 76 characters.
     * If the first line needs to be shorter, indicate the difference with
     * $firstLineOffset.
     */
    public function encodeString(string $string, ?string $charset = 'utf-8', int $firstLineOffset = 0, int $maxLineLength = 0): string
    {
        if (0 &gt;= $maxLineLength || 76 &lt; $maxLineLength) {
            $maxLineLength = 76;
        }

        $encodedString = base64_encode($string);
        $firstLine = '';
        if (0 !== $firstLineOffset) {
            $firstLine = substr($encodedString, 0, $maxLineLength - $firstLineOffset).&quot;\r\n&quot;;
            $encodedString = substr($encodedString, $maxLineLength - $firstLineOffset);
        }

        return $firstLine.trim(chunk_split($encodedString, $maxLineLength, &quot;\r\n&quot;));
    }
}
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