how to get substring or part of string from a url in c#

Question

I have an application where uses post comments. Security is not an issue. string url = http://example.com/xyz/xyz.html?userid=xyz&comment=Comment

What i want is to extract the userid and comment from above string. I tried and found that i can use IndexOf and Substring to get the desired code BUT what if the userid or comment also has = symbol and & symbol then my IndexOf will return number and my Substring will be wrong. Can you please find me a more suitable way of extracting userid and comment. Thanks.

No. You can get them from the Response object, I believe, as query string values. — user1228
– user1228, Commented Jun 5, 2015 at 14:46
possible duplicate of Get url parameters from a string in .NET — Markus
– Markus, Commented Jun 5, 2015 at 14:50

Habib · Accepted Answer · 2015-06-05 14:53:42Z

5

I got url using string url = HttpContext.Current.Request.Url.AbsoluteUri;

Do not use AbsoluteUri property , it will give you a string Uri, instead use the Url property directly like:

var result = System.Web.HttpUtility.ParseQueryString(HttpContext.Current.Request.Url.Query);

and then you can extract each parameter like:

Console.WriteLine(result["userid"]);
Console.WriteLine(result["comment"]);

For other cases when you have string uri then do not use string operations, instead use Uri class.

Uri uri = new Uri(@"http://example.com/xyz/xyz.html?userid=xyz&comment=Comment");

You can also use TryCreate method which doesn't throw exception in case of invalid Uri.

Uri uri;
if (!Uri.TryCreate(@"http://example.com/xyz/xyz.html?userid=xyz&comment=Comment", UriKind.RelativeOrAbsolute, out uri))
{
    //Invalid Uri
}

and then you can use System.Web.HttpUtility.ParseQueryString to get query string parameters:

 var result = System.Web.HttpUtility.ParseQueryString(uri.Query);

edited Jun 5, 2015 at 14:53

answered Jun 5, 2015 at 14:45

Habib

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8 Comments

drmaa Over a year ago

I am newbie, can you please suggest how can i extract xyz and Comment from the above link after using uri

drmaa Over a year ago

I got url using string url = HttpContext.Current.Request.Url.AbsoluteUri; Now i do Uri uri = new Uri(@url); var result = System.Web.HttpUtility.ParseQueryString(uri.Query);

yazanpro Over a year ago

Remember that IndexOf is always there when you need it.

Habib Over a year ago

@Asbat, thats great, do not use AbsoluteUri, instead use Url directly, without converting it to string.

Habib Over a year ago

@Asbat, I have modified the answer

|

JGInternational · Accepted Answer · 2015-06-05 14:51:01Z

0

The ugliest way is the following:

String url = "http://example.com/xyz/xyz.html?userid=xyz&comment=Comment";
usr = url.Split('?')[1];
usr= usr.Split('&')[0];
usr = usr.Split('=')[1];

But @habib version is better

answered Jun 5, 2015 at 14:51

JGInternational

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2 Comments

drmaa Over a year ago

But as my question say, it will fail I assume if user id or comment contain ? & =

JGInternational Over a year ago

That will be an invalid url then

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