How to validate a URL?

Question

1.00/5 (1 vote)

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hello
i want to validate a URL in combobox.and i have tried; but i have one problem like when i type https://www.facebook then message come like valid Url.

but these is not correct . when i type https://www.facebook.com then message should come as valid Url other wise it should display invalid Url

and the code i have tried is

C#

using System.Text.RegularExpressions;

 public static bool isValidUrl(string url)
        {
            
            string pattern = @"^(http|https|ftp|)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(:[a-zA-Z0-9]*)?/?([a-zA-Z0-9\-\._\?\,\'/\\\+&%\$#\=~])*[^\.\,\)\(\s]$";
            Regex reg = new Regex(pattern, RegexOptions.Compiled | RegexOptions.IgnoreCase);
            return reg.IsMatch(url);
        }

C#

private void comboBox_Url_Validating(object sender, CancelEventArgs e)
       {
           bool s = isValidUrl(comboBox_Url.Text);
           if (s)
           {
               MessageBox.Show("URL is valid.");
              
           }
           else
           {
               MessageBox.Show("In valid URL.");
               this.comboBox_Url.Focus();
           }

Posted 4-Aug-11 1:29am

rbnsubedi01

Updated 6-Aug-11 20:47pm

Sergey Alexandrovich Kryukov

v4

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Prerak Patel · Answer 1 · 2011-08-04T01:41:00

Solution 1

Here is the general expression

^(ht|f)tp(s?)\:\/\/[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*(:(0-9)*)*(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&amp;%\$#_]*)?$

Ref:http://msdn.microsoft.com/en-us/library/ff650303.aspx[^]

For your question, if you restrict http://www.facebook then what about http://google.com. You can even have http://localhost as valid address. So, I don't see anything wrong in your expression saying that url is valid. Still you can customize it your way.

Posted 4-Aug-11 1:41am

Prerak Patel

Comments

UJimbo 4-Aug-11 7:45am

I think what he's trying to say is that Regex finds http://www.facebook as a valid url, but it's not since it's missing the final .com part

Prerak Patel 4-Aug-11 7:47am

But if he make it invalid, http://google.com and http://localhost will also be invalid. And that is not true. This is my point.

UJimbo 4-Aug-11 7:49am

I see what you mean

BobJanova 4-Aug-11 8:59am

It is a valid URL, though. It doesn't find anything but you can set up local DNS so that it does.

rbnsubedi01 4-Aug-11 7:51am

i want like http://www.facebook as a valid url, but it's not since it's missing the final .com part. so how can i valid that last part.

UJimbo 4-Aug-11 7:57am

As in guess the proper extension for the URL last part? That will be a bit ambiguous though, won't it?

UJimbo · Answer 2 · 2011-08-04T01:48:00

Solution 2

try the following:

Check If A Url Works in C#

And this:

C# URL Checker

Worked for me, I like the timeout part from the second link better

Posted 4-Aug-11 1:48am

UJimbo

Updated 4-Aug-11 1:51am

v2

thatraja · Answer 3 · 2011-08-04T18:33:00

Solution 3

I recommend the following freeware to regular expression things
Expresso 3.0 - The premier regular expression development tool[^]

Posted 4-Aug-11 18:33pm

thatraja

Gordon Beeming · Answer 4 · 2011-08-07T09:05:00

If you want to do a check if a url is valid the not so good way to do this is use the Uri class

C#

Uri myUrl = new Url(someString);

This will break if the url is invalid. The Constructor of the Uri class is

C#

if (uriString == null)
        throw new ArgumentNullException("uriString");
      else
        this.CreateThis(uriString, false, UriKind.Absolute);

The CreateThis throws an exception if the uri is invalid.

If you like me and don't like the try catch way of working you can use

C#

Uri myUrl = null;
            if (Uri.TryCreate(someString, UriKind.Absolute, out myUrl))
            {
                //Valid Url
            }
            else
            {
                //Invalid Url
            }