some helper function

index.php

<?php

/**
     * detect hastag from string
     *
     * @param  [string] $string
     * @return [array]
     */
    public function detectHastag($string)
    {
        $pattern = '/\s*#+\s*/im';

        if (preg_match_all($pattern, $string, $matches)) {
            return $matches[0];
        }

        return null;
    }

    /**
     * convert hashtag to number
     *
     * @param  [string] $hash
     * @param  [number] $default
     * @return [string]
     */
    public function hastagToNumber($hash, $default = null)
    {
        $number = '';
        $zero   = strlen($hash);
        if (! $default) {
            $number = sprintf("%0".$zero."s", 1);
        } else {
            if (strlen($hash) <= strlen($default)) {
                $number = $default;
            } else {
                $number = sprintf("%0".$zero."s", $default);
            }
        }

        return $number;
    }