echo into variable or the like

Hi, this is my first post so forgive me if I missed a rule and do something wrong.

I have this code,

echo $_SERVER['PHP_SELF']."?";
foreach ($_GET as $urlvar=>$urlval)
echo $urlvar."=".$urlval."&";

It works by it’s self. 
I want to insert the output in a table.  Is there a way to ‘echo’ into a variable(i.e. make the output of this echo the value of a variable) or am I on the wrong track all together?