Start index cannot be less than zero and " problem

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hi when i try to use it it says "startindex cannot be less then zero" in 8th line and i need to write <pre class="df-raw" id="registryData"> but when i try to put it into "" class and other 2 words stays outside of the "" pls help me

What I have tried:

C#

string website =("https://www.whois.com/whois/" + domainname.ToString());
            WebRequest request = HttpWebRequest.Create(website);
            WebResponse answer;
            answer = request.GetResponse();
            StreamReader info = new StreamReader(answer.GetResponseStream());
            string cinfo = info.ReadToEnd();
            int start = cinfo.IndexOf("<pre class="df-raw" id="registryData">");
            int finish = cinfo.Substring(start).IndexOf("</pre>");
           string scinfo = cinfo.Substring(start,finish);
            rtxtregistery.Text = scinfo;

Posted 2-Sep-17 2:04am

istemihan

Updated 2-Sep-17 2:23am

Thomas Daniels

v2

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Comments

Richard MacCutchan 2-Sep-17 7:16am

It means that one of your values is -1 which indicates that it did not find the pattern you are searching for.

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Graeme_Grant · Accepted Answer · 2017-09-02T02:23:00

The documentation[^] states:

Quote:
The zero-based index position of value if that string is found, or -1 if it is not. If value is String.Empty, the return value is 0.

C#

int start = cinfo.IndexOf("<pre class="df-raw" id="registryData">");
int finish = cinfo.Substring(start).IndexOf("</pre>");

You are assuming that the text exists... To fix:

C#

int start = cinfo.IndexOf("<pre class=\"df-raw\" id=\"registryData\">");
if (start >= 0)
{
    int finish = cinfo.Substring(start).IndexOf("</pre>");
    if (finish >= 0)
    {
        rtxtregistery.Text = cinfo.Substring(start, finish);
    }
}

Start index cannot be less than zero and " problem

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Start index cannot be less than zero and " problem

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Solution 1

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