check whether submitted url is valid

[bull]

Hi,

i am making comment script in php and want to know how to check whether user submitted homepage url is valid.

i dont want nothing complex, just check if it starts with http:// and dont contain symbols that cant be used in url

cant you give me code or link?
and where i can read what symbols cant be used in url?

[laserlight]

A user has posted what might work for you in the Code Critique forum: url validator.

[jmack159]

how about this:

if(ereg("^[http://]{1}([^[:space:]]*)[:alnum:]+[(\.){1}[:alnum:]]+(\/)[[:alnum]#?/&=]$" , $url)){
    //url valid
}else{
    //url not valid
}

found this here: http://p2p.wrox.com/topic.asp?TOPIC_ID=2595

a google search for url validation will bring up some variations

edit: laserlight: your too fast for me!

[bull]

my mistake..

[bull]

i tried it, but in my case it doesnt work. i need it also accept links with variables after /,

like - http://abc.com/?id=12&cat=2#12

your mentioned script says,
NO!, http://abc.com/?id=12&cat=2#12 is NOT a valid url

how to improve that script?

function is_valid_url($url) {
  $pattern = "#^(http:\/\/|https:\/\/|www\.)(([A-Z0-9][A-Z0-9_-]*)(\.[A-Z0-9][A-Z0-9_-]*)+)(:(\d+))?(\/)*$#i";
  if (!preg_match($pattern, $url)) {
    return false;
  } else {
    return true;
  }
} // is_valid_url()

$str = '//example.com';
if (is_valid_url($str)) {
  echo 'YES, ' . $str . ' is a valid url';
} else {
  echo 'NO!, ' . $str . ' is NOT a valid url';
}