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){
    $qian=array(" "," ","	","
","
");
    return str_replace($qian, '', $str);   
}
//多个连续空格只保留一个

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