php-school / learn-you-php

     * @param  int     $index     The index at which to insert the substring

     * @return Stringy Object with the resulting $str after the insertion

     */

    public function insert($substring, $index)

    {

        $stringy = static::create($this->str, $this->encoding);

        if ($index > $stringy->length()) {

            return $stringy;

        }

        $start = mb_substr($stringy->str, 0, $index, $stringy->encoding);

        $end = mb_substr($stringy->str, $index, $stringy->length(),

            $stringy->encoding);

        $stringy->str = $start . $substring . $end;

        return $stringy;

    }

    /**

     * Returns true if the string contains only alphabetic chars, false

     * @param  string  $substring The substring to append if it can fit

     * @return Stringy Object with the resulting $str after truncating

     */

    public function truncate($length, $substring = '')

    {

        $stringy = static::create($this->str, $this->encoding);

        if ($length >= $stringy->length()) {

            return $stringy;

        }

        // Need to further trim the string so we can append the substring

        $substringLength = mb_strlen($substring, $stringy->encoding);

        $length = $length - $substringLength;

        $truncated = mb_substr($stringy->str, 0, $length, $stringy->encoding);

        $stringy->str = $truncated . $substring;

        return $stringy;

    }

    /**

     * Returns a lowercase and trimmed string separated by underscores.