[PHP知识库]php每隔多少字插入字符折行换行

/**
 * Notes:字符串每隔多少个字符加个换行
 * User: zhixinhua
 * DateTime: 2021/8/11 15:52
 * @param $string 截取的字符串
 * @param $num   间隔的字符数
 * @param $insert_str  替换的字符串
 * @param false $once   是否返回截取的第一段
 * @return string
 */
function str_fold_line($string, $num, $insert_str, $once = false)
{
    //$string = iconv('gb2312', 'utf-8//ignore', $string);
    $array = array();
    $strlen = mb_strlen($string);
    while($strlen){
        $array[] = mb_substr($string, 0, $num, "utf-8");
        if($once)
            return $array[0] . $insert_str;
        $string = mb_substr($string, $num, $strlen, "utf-8");
        $strlen = mb_strlen($string);
    }
    return implode($insert_str, $array);
}