verify a PHP variable and get result from it - php

Question

Here is my code:-
<?php
$URL = "http://www.mylink.com/show_album/XXXXX";
/*The value of $URL will be passed from previous page via Form*/
?>
First, The value of the variable must be a link/URL. If not, echo "Not an URL"; should be executed. But, I am unable to check if it's a link or not. Please, anyone help me to figure out this. As a newbie, I need help badly.
Second, The http:// is optional. If provided, it's okay. Else, "http://" will be added automatically. I used this code for this and it works.
if(strpos($URL, "http://") !== false){
echo $URL;
echo "<br />http:// already provided";
return $URL;
}
else {
echo "http://" . $URL;
$URL = "http://" . $URL;
echo "<br />http:// automatically added";
return $URL;
}
Third, The text "mylink.com/show_album/" (without quote) must be available in $URL. I used this code for this:-
if (strpos($URL, "mylink.com/show_album/") !== false){
echo "The "mylink.com/show_album/ is available";
}
else {
echo "The "mylink.com/show_album/ is not available";
}
It's okay.
Next, In the $URL, the value is a link name with a last word XXXXX. It must be the last word of this variable. XXXXX is a number. It can be any number like "12345" or any other. But, I want to get the Number from this $URL and show it. How can I do this?
At last, The link can only contain http:// and www.mylink.com/show_album/XXXXX . Otherwise, the echo "Not a valid link"; will be executed. How to do this?

Answer 1

For Validating URLs:
$text = preg_replace("
#((http|https|ftp)://(\S*?\.\S*?))(\s|\;|\)|\]|\[|\{|\}|,|\"|'|:|\<|$|\.\s)#ie",
"'$3$4'",
$text
);
For validating/appending http:// on front of URL, do something like:
$protocol = substr($URL, 0, 7);
if($protocol!="http://")
{
$URL="http://".$URL;
}
EDIT
Now for fetching the last numbers:
$XXXXX=substr( $URL, strrpos( $url, '/' )+1 );