How to validate URL if valid or invalid if the entry is like this in C#

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1.00/5 (1 vote)

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How to validate URL if valid or invalid if the entry is like this:

www.com - should be invalid
http://ww.try.net - should be invalid
http://winner.com - should be valid
url = null = should be invalid

Below is the method I made which does not validate the above scenario.

Thank you in advance for your kind help

What I have tried:

C#

<pre> public bool IsUrlValid(string webUrl)
        {
            if (webUrl == null) return false;
            return Regex.IsMatch(webUrl, @"(http|https)://(([www\.])?|([\da-z-\.]+))\.([a-z\.]{2,3})$");
        }

Posted 17-Jan-17 19:24pm

Silver Lightning

Updated 17-Jan-17 22:47pm

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Comments

Maciej Los 18-Jan-17 2:31am

And what's wrong with your Regex pattern?

3 solutions

Solution 2

By itself, 'http://ww.try.net' is a valid url.
the 'www' is only the most common value used at this place, but any value is authorized, including no value.

Posted 17-Jan-17 21:43pm

Patrice T

Comments

Silver Lightning 18-Jan-17 4:02am

thanks sir, but can you give me an updated regex code to set the http://ww.try.net' to become invalid?

Solution 3

try this:-

string pattern = @"/\b(http|https)\:\/\/(www\.)?[a-z]+\.[a-z]{2,3}\b/g";
// Instantiate the regular expression object.
Regex r = new Regex(pattern , RegexOptions.IgnoreCase);

// Match the regular expression pattern against a text string.
var m = r.Match(webUrl);

Posted 17-Jan-17 22:47pm

Singh Deepika

Comments

Silver Lightning 18-Jan-17 5:30am

Thanks Singh
It's always resulting to invalid URL even the input URL is valid:

sample valid URL:
http://www.bigwinnerme.com

Could you elaborate more?

Singh Deepika 18-Jan-17 6:19am

the regex is matching input string "http://www.bigwinnerme.com". Checkout at regexstorm.

What check are you applying. If the string wont match it will return Null. Also, you could test your regular expression here : http://regexstorm.net/tester

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Maciej Los · Accepted Answer · 2017-01-17T20:35:00

Solution 1

No matter of regex pattern, there's inbuilt function: Uri.IsWellFormedUriString Method (String, UriKind) (System)[^]

Exmaple:

C#

List<string> uris = new List<string>(){"www.com", "http://ww.try.net", "http://winner.com", "url = null"};

var result = uris.Select(x=> new {Uri = x, IsValid = Uri.IsWellFormedUriString(x, UriKind.Absolute)});

foreach(var u in result)
{
	Console.WriteLine("'{0}' is{1}valid", u.Uri, u.IsValid ? " ":" NOT ");
}

Result:

'www.com' is NOT valid
'http://ww.try.net' is valid
'http://winner.com' is valid
'url = null' is NOT valid

In case, you want to use Regex instead, you can use this: ^http(s)?://([\w-]+.)+[\w-]+(/[\w- ./?%&=])?$

Posted 17-Jan-17 20:35pm

Maciej Los

Updated 17-Jan-17 21:23pm

v2

Comments

Peter Leow 18-Jan-17 2:42am

That is handy, 5ed!

Maciej Los 18-Jan-17 2:47am

Thank you, Peter.

Silver Lightning 18-Jan-17 4:32am

Thank you sir. but
'http://ww.try.net' is Invalid (requirement)

because ww. should be www.
how can I adjust the regex to validate that the above URL is INVALID?

F-ES Sitecore 18-Jan-17 4:57am

ww.try.net is a valid URL. How can you come up with a regex that reads peoples minds and knows that someone meant "www" and not "ww". If you are coming up with your own arbitrary rules that say what a valid URL is then you'll need to come up with a regex that satisfies what those rules are. We don't know what *you* consider to be a valid URL, only what the standards say is a valid url and ww.try.net is a valid URL.

Silver Lightning 18-Jan-17 5:21am

Thanks sir. how about the URL link like this?
https://www.com
How could I make this invalid when the user input a URL like on the above case?