PHP删除字符串中的空格和换行符 将字符串中的连续多个空格转换为一个空格

//删除空格和回车
function trimall($str){
    $qian=array(" ","　","\t","\n","\r");
    return str_replace($qian, '', $str);
}

//多个连续空格只保留一个

function merge_spaces($string){
    return preg_replace("/\s(?=\s)/","\\1",$string);
}