php 字符串 包孕 比较 替换

<?php


$url1="http://www.163.com";
$url2="www.163.com";
$url3="xxxxhttp://www.163.com";

$rooturl="xxx";
echo "".strrpos($url1,"http://")."\n";
echo "".strrpos($url2,"http://")."\n";
echo "".strrpos($url3,"http://")."\n";

if(strrpos($url1,"http://")!==false && strrpos($url1,"http://")==0){
echo str_ireplace("http://","",$url1)."__1 have \n";
}

if(strrpos($url2,"http://")!==false && strrpos($url2,"http://")==0){
echo "2 have  \n";
}

if(strrpos($url3,"http://")!==false && strrpos($url3,"http://")==0){
echo "3 have  \n";
}


echo  "".$rooturl."\n";

?>