array iteration in php

<?
$ar=array('as','ae','sd');
$ad=array("r"=>"red","o"=>"orange","b"=>"blue");

################# 1 st way###############
while($elem=current($ad))
{
    print key($ad);
   
    next($ad);
}

####################second way ############
$cur_item=current($ad);
print"<p/>". $cur_item;

while($cur_item=next($ad))
{
    print"<p/>". $cur_item;
}
foreach (array_keys($ad) as $key)
{
    print"<p/>".$key."==>>".$ad[$key];
}
####################Third  way ############

foreach($ad as $elem)
{
    print"<p/>".$elem."   elem";
}
?>