[RESOLVED] [2.0] how to validate uri?

how do i check if a uri is valid and contains "http://" at the start of it?
eg: "www.google.com" is invalid but "http://www.google.com" is valid.

is there some class method in .net to check this or do i need to use regex?
(i have looked at the online msdn, but might have missed something...)

Use either string.StartsWith() or string.SubString()

VB Code:

string s = "http://w3c.org";
 
//method 1
if(s.StartsWith("http://"))
    MessageBox.Show("URI has http://");
else
    MessageBox.Show("URI don't have http://");
 
//method 2
s = "http//www.google.org";
if(s.Substring(0,7)=="http://")
    MessageBox.Show("URI has http://");
else
    MessageBox.Show("URI don't have http://");

great! thanks for the help :thumb:

Also have a look in the System.Uri namespace.

Quote:

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Originally Posted by penagate

Also have a look in the System.Uri namespace.

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Thanks for mentioning that again...

Trying to create a new instance of System.Uri without the 'http://' in the address results in an UriFormatException :thumb:

EDIT: System.Uri is a class, not a namespace :)

Eh... yes. My mistake.

for anyone else that might stumble upon this thread, here is some sample code of my solution to the problem:

Code:

---

using System;

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine(isValidUri(@"www.google.com").ToString());
        Console.WriteLine(isValidUri(@"http://www.google.com").ToString());
        Console.ReadLine();
    }

    public bool isValidUri(string uri)
    {
        try
        {
            Uri address = new Uri(uri);
            return true;
        }
        catch (UriFormatException ex)
        {
            return false;
        }
    }
}

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A regular expression would save you the trouble of excessive overhead involved in exceptions:
http://regexlib.com/Search.aspx?k=url
http://regexlib.com/REDetails.aspx?regexp_id=1363

Code:

---

// RegEx is found at System.Text.RegularExpressions.

                /// <summary>
                /// <para>Tests if the provided URL is valid.</para>
                /// <para>Supports address, IP address, with or without the protocol, optional port numbers, directory path,
                /// file name (with extension), and parameter pairs.</para>
                /// </summary>
                /// <param name="url">The URL to test.</param>
                /// <returns>True if the URL is valid, else false.</returns>
                private bool IsValidUrl(string url)
                {
                        const string URL_REGEX = @"(?#WebOrIP)((?#protocol)((http|https):\/\/)?(?#subDomain)(([a-zA-Z0-9]+\.(?#domain)[a-zA-Z0-9\-]+(?#TLD)(\.[a-zA-Z]+){1,2})|(?#IPAddress)((25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9])\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[1-9]|0)\.(25[0-5]|2[0-4][0-9]|[0-1]{1}[0-9]{2}|[1-9]{1}[0-9]{1}|[0-9])))+(?#Port)(:[1-9][0-9]*)?)+(?#Path)((\/((?#dirOrFileName)[a-zA-Z0-9_\-\%\~\+]+)?)*)?(?#extension)(\.([a-zA-Z0-9_]+))?(?#parameters)(\?([a-zA-Z0-9_\-]+\=[a-z-A-Z0-9_\-\%\~\+]+)?(?#additionalParameters)(\&([a-zA-Z0-9_\-]+\=[a-z-A-Z0-9_\-\%\~\+]+)?)*)?";
                        Regex urlTest = new Regex(URL_REGEX, RegexOptions.IgnoreCase | RegexOptions.Compiled);
                        return urlTest.IsMatch(url);
                }

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