[RESOLVED] How would I validate a URL

coollittlew

I have a form in which a user is required to enter a URL I would like to validate it to make sure a URL had been entered and that it ends in a cirtain file extention for example .jpg:

http://mysite.com/picture.jpg would be valid
http://mysite.com/picture.bmp would be invalid

http://www.myfiles.com/files/image.jpg would be valid
http://www.myfiles.com/files/image.gif would not be valid

How would I do this?

Thanks,
Kris

justsomeone

you need to use regular expressions.

See here for a discussion of a sample regular expression which will match a URL. You can easily change this to ensure that it ends with "jpg".

You could go further if you like and, when you have verified that it is a url ad ends in ".jpg", you could try to access the file to make sure it exists.

coollittlew

That would be quite cool but it sounds a little advance for me though. Thank you I will have a look.

coollittlew

Ok I think I understand what I need to be doing I just cant seem to do it. I have found examples on how to validate a URL but I am unsure on how I would adapt it to check for a cirtain extention.

bradgrafelman

The article linked above provides the regexp pattern for validating an URL, so you can use a function such as [man]preg_match/man to make sure the URL given matches the pattern. If it doesn't, it's not valid.

Next, use [man]basename[/man] to get the filename part of the URL. Now that you have the filename, it's simply a matter of using [man]explode/man to explode the string on the period(s), and look at the last element in the array. In case you don't know how to do this, here's an example of using explode and accessing the last element of an array:

$path = 'http://www.thisisatest.com/images/my.test.image.jpeg';

$filename_array = explode('.', basename($path) );

echo $filename_array[(count($filename_array)-1)]; // echo's 'jpeg'

Houdini

Try using this preg_match function, change the values for the $url and you will see how it works and you can then modify the code to do what you want.

$url="http://somewhere.com/images/test.gif";
if (preg_match("/(.+?).(jpg|jpeg)/i",$url)){
  echo $url." is a jpeg or jpg";
}
else {
  echo$url." is not a jpeg or jpg";
}

coollittlew

Thanks alot I have managed to get it working now. Your help is much appreciated.

justsomeone

Delighted to hear it. Well done 🙂