[PHP] PHP: Ajax send()

[germana]

Hi!!

Im trying to sent data to and php with Ajax, so..
this is what im sending>_url= "table='historia'$'='$''$'string'$''&";

then i do:

_url = _url.substring(0,_url.length-1)  //quita el & de sobra al final
var ajax = nuevoAjax();
        ajax.open("POST", "atrapalo_x.php", true);
        ajax.setRequestHeader("Content-Type",
"aplication/x-www-form-urlencoded");
        ajax.send(_url);
        
        ajax.onreadystatechange = function()
        {
                if(ajax.readyState == 4)
                {
                        alert(ajax.responseText)
                        .
                        .
                        .
..............

and in the php i do:

$datafield=explode("$",str_replace("\'","'",$_POST["table"]));
$main_table="".str_replace("'","",$datafield[0])."";
$main_table=strtolower($main_table);

but when i do and echo $datafield[0] or echo $main_table

it returns          nothing... just blank