PHP 之查找字符串位置函数封装

/**
 * 正数查找字符串n次出现的位置
 * @param $str
 * @param $find
 * @param $n
 * @return bool|int
 */
function str_n_pos($str, $find, $n = 1)
{
    $pos_val = 0;
    for ($i = 1; $i <= $n; $i++) {
        $pos = strpos($str, $find);
        $str = substr($str, $pos + 1);
        $pos_val = $pos + $pos_val + 1;
    }
    return $pos_val - 1;
}

/**
 * 逆数查找字符串n次出现的位置
 * @param $str
 * @param $find
 * @param $n
 * @return bool|int
 */
function str_n_rpos($str, $find, $n = 1)
{
    $pos_val = 0;
    for ($i = 1; $i <= $n; $i++) {
        $pos = strrpos($str, $find);
        $str = substr($str, 0, $pos);
        $pos_val = $pos;
    }
    return $pos_val;
}