Develop Reference

How to extract an url from a String in C#

I have this string :
"<figure><img
src='http://myphotos.net/image.ashx?type=2&image=Images\\2\\9\\11\\12\\3\\8\\4\\7\\685621455625.jpg'
href='JavaScript:void(0);' onclick='return takeImg(this)'
tabindex='1' class='myclass' width='55' height='66' alt=\"myalt\"></figure>"
How can I retrieve this link :
http://myphotos.net/image.ashx?type=2&image=Images\\2\\9\\11\\12\\3\\8\\4\\7\\685621455625.jpg
All string are the same type so somehow I need to get substring between src= and href. But I don't know how to do that. Thanks.

If you parse HTML don't not use string methods but a real HTML parser like HtmlAgilityPack:
var doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(html); // html is your string
var linksAndImages = doc.DocumentNode.SelectNodes("//a/#href | //img/#src");
var allSrcList = linksAndImages
.Select(node => node.GetAttributeValue("src", "[src not found]"))
.ToList();

You can use regex:
var src = Regex.Match("the string", "<img.+?src=[\"'](.+?)[\"'].*?>", RegexOptions.IgnoreCase).Groups[1].Value;

In general, you should use an HTML/XML parser when parsing a value from HTML code, but with a limited string like this, Regex would be fine.
string url = Regex.Match(htmlString, #"src='(.*?)'").Groups[1].Value;

If your string is always in same format, you can easily do this like so :
string input = "<figure><img src='http://myphotos.net/image.ashx?type=2&image=Images\\2\\9\\11\\12\\3\\8\\4\\7\\685621455625.jpg' href='JavaScript:void(0);' onclick='return takeImg(this)' tabindex='1' class='myclass' width='55' height='66' alt=\"myalt\"></figure>";
// link is between ' signs starting from the first ' sign so you can do :
input = input.Substring(input.IndexOf("'")).Substring(input.IndexOf("'"));
// now your string looks like : "http://myphotos.net/image.ashx?type=2&image=Images\\2\\9\\11\\12\\3\\8\\4\\7\\685621455625.jpg"
return input;

string str = "<figure><imgsrc = 'http://myphotos.net/image.ashx?type=2&image=Images\\2\\9\\11\\12\\3\\8\\4\\7\\685621455625.jpg'href = 'JavaScript:void(0);' onclick = 'return takeImg(this)'tabindex = '1' class='myclass' width='55' height='66' alt=\"myalt\"></figure>";
int pFrom = str.IndexOf("src = '") + "src = '".Length;
int pTo = str.LastIndexOf("'href");
string url = str.Substring(pFrom, pTo - pFrom);
Source :
Get string between two strings in a string

Q is your string in this case, i look for the index of the attribute you want (src = ') then I remove the first few characters (7 including spaces) and after that you look for when the text ends by looking for '.
With removing the first few characters you could use .IndexOf to look for how many to delete so its not hard coded.
string q =
"<figure><img src = 'http://myphotos.net/image.ashx?type=2&image=Images\\2\\9\\11\\12\\3\\8\\4\\7\\685621455625.jpg' href = 'JavaScript:void(0);' onclick = 'return takeImg(this)'" +
"tabindex = '1' class='myclass' width='55' height='66' alt=\"myalt\"></figure>";
string z = q.Substring(q.IndexOf("src = '"));
z = z.Substring(7);
z = z.Substring(0, z.IndexOf("'"));
MessageBox.Show(z);
This is certainly not the most elegant way (look at the other answers for that :)).

Finding whats between two entered strings using regex?

I am working on a simple facebook messenger client (without the need of a developer account) and so far what i have achieved is getting all my messages - name, preview, time. What i'd like to find is the users href link
so far i have this:
MatchCollection name = Regex.Matches(
htmlText, "<div class=\"_l2\">(.*?)</div>");
MatchCollection preview = Regex.Matches(
htmlText, "<div class=\"_l3 fsm fwn fcg\">(.*?)</div>");
MatchCollection time = Regex.Matches(
htmlText, "<div class=\"_l4\">(.*?)</div>");
which fully works.
but i've tried a few things that i found on this website but nothing seemed to work. The href goes like: <a class="_k_ hoverZoomLink" rel="ignore" href="
and ends with a ". Could someone refer me to an article that actually might help me know how i can get that href. Or even a better way of doing it other than regex but i would really prefer regex:
for (int i = 0; i < name.Count; i++)
{
String resultName = Regex.Replace(name[i].Value, #"<[^>]*>", String.Empty);
String newName = resultName.Substring(0, resultName.Length - 5);
String resultPreview = Regex.Replace(preview[i].Value, #"<[^>]*>", String.Empty);
String s = time[i].Value;
int start = s.IndexOf("data-utime=\"") + 28;
int end = s.IndexOf("</abbr>", start);
String newTime = s.Substring(start, (end - start));
threads.Add(new Thread(newName, resultPreview, newTime, ""));
}
Thanks in advanced.

Use a real html parser like HtmlAgilityPack
var doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(htmlstring);
var link = doc.DocumentNode.SelectSingleNode("//a[#class='_k_ hoverZoomLink']")
.Attributes["href"].Value;
Instead of XPath, you can use Linq too
var link = doc.DocumentNode.Descendants("a")
.Where(a => a.Attributes["class"] != null)
.First(a => a.Attributes["class"].Value == "_k_ hoverZoomLink")
.Attributes["href"].Value;

How to get the center part of string on C#

i need the center string of Rocky44 only using C#
Hi <span>Rocky44</span>
I tried the some split method but can't work
string[] result = temp.Split(new string[] { "<span>" , "</span>" }, StringSplitOptions.RemoveEmptyEntries);
Example:
Hi <span>Rocky44</span>
To:
Rocky44

Use an html parser. I will give an example using HtmlAgilityPack
string html = #"Hi <span>Rocky44</span>";
var doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(html);
var text = doc.DocumentNode.SelectSingleNode("//span").InnerText;

You're on the right track; you're just not escaping your quotes correctly:
string[] result = temp.Split(new string[] { "<span>" , "</span>" }, StringSplitOptions.RemoveEmptyEntries);
Of course, this is assuming that your input will always be in exactly the given format. As I4V mentions, an HTML parser may come in handy if you're trying to do anything more complicated.

If you're only going to get this sort of thing (eg this sort of HTML) then I would use regex. Else, DO NOT USE IT.
string HTML = #"Hi <span>Rocky44</span>"
var result = Regex.Match(HTML, #".*<a.*><span.*>(.*)</span></a>").Groups[1].Value;

Find the index of <span> and </span> using the IndexOf method.
Then (adjusting for the length of <span>) use the String.Substring method to get the desired text.
string FindLinkText(string linkHtml)
{
int startIndex = linkHtml.IndexOf("<span>") + "<span>".Length,
length = linkHtml.IndexOf("</span>") - startIndex;
return linkHtml.Substring(startIndex, length);
}

Get a value from a webpage c#

I a have a string that contains the code of a webpage.
This is an example:
<input type="text" name="x4B07" value="650"
onchange="this.form.x8000.value=this.name;this.form.submit();"/>
<input type="text" name="x4B08" value="250"
onchange="this.form.x8000.value=this.name;this.form.submit();"/>
In that string I want to get the 650 and 250 (these are variables and they change value).
How can I do so?
Example:
name
value
x4b08
254
x4b07
253
x4b06
252
x4b05
251

If you were confident that the markup would never change (and you have a simple snippet like your example line) a regex could get you those values, for example:
Regex re = new Regex("name=\"(.*?)\" value=\"(.*?)\"");
Match match = re.Match(yourString);
if(match.Success && match.Groups.Count == 3){
String name = match.Groups[1];
String value = match.Groups[2];
}
Alternatively you could parse the page content and query the resulting document for the elements, and then extract the values. (C# HTML Parser: Looking for C# HTML parser )

You can use regular expressions to match value="([0-9]*)"
Or you can look for the string "value" using string.IndexOf and then take the following few characters.

This should work for you (assuming that s contains the string you want to parse):
string value = s.Substring(s.IndexOf("value=")+7);
value = value.Substring(0, value.IndexOf("\""));

How specific are your examples? Could you also want to extract varying length alphabetic strings? Will the strings you want to extract always be properties?
While the regex/substring way works for the specified examples I think they will scale quite badly.
I'd parse the HTML using a parser (see ndtreviv's answer) or possibly with an XML parser (if the HTML is valid XHTML). That way you will get better control and don't have to bleed your eyes out from fidgeting with a bucketload of regex.

If you have multiple such controls in the form of string you can create and XmlDocument and iterate through it.

just solved with this
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(URL);
HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
Stream st = resp.GetResponseStream();
StreamReader sr = new StreamReader(st);
string buffer = sr.ReadToEnd();
ArrayList uniqueMatches = new ArrayList();
Match[] retArray = null;
Regex RE = new Regex("name=\"(.*?)\" value=\"(.*?)\"", RegexOptions.Multiline);
MatchCollection theMatches = RE.Matches(buffer);
for (int counter = 0; counter < theMatches.Count; counter++)
{
//string[] tempSplit = theMatches[counter].Value.Split('"');
Regex reName = new Regex("name=\"(.*?)\"");
Match matchName = reName.Match(theMatches[counter].Value);
Regex reValue = new Regex("value=\"(.*?)\"");
Match matchValue = reValue.Match(theMatches[counter].Value);
string[] dados = new string[2];
dados[0] = matchName.Groups[1].ToString();
dados[1] = matchValue.Groups[1].ToString();
uniqueMatches.Add(dados);
}
Tks all for the help

How can I strip HTML tags from a string in ASP.NET?

Using ASP.NET, how can I strip the HTML tags from a given string reliably (i.e. not using regex)? I am looking for something like PHP's strip_tags.
Example:
<ul><li>Hello</li></ul>
Output:
"Hello"
I am trying not to reinvent the wheel, but I have not found anything that meets my needs so far.

If it is just stripping all HTML tags from a string, this works reliably with regex as well. Replace:
<[^>]*(>|$)
with the empty string, globally. Don't forget to normalize the string afterwards, replacing:
[\s\r\n]+
with a single space, and trimming the result. Optionally replace any HTML character entities back to the actual characters.
Note:
There is a limitation: HTML and XML allow > in attribute values. This solution will return broken markup when encountering such values.
The solution is technically safe, as in: The result will never contain anything that could be used to do cross site scripting or to break a page layout. It is just not very clean.
As with all things HTML and regex:
Use a proper parser if you must get it right under all circumstances.

Go download HTMLAgilityPack, now! ;) Download LInk
This allows you to load and parse HTML. Then you can navigate the DOM and extract the inner values of all attributes. Seriously, it will take you about 10 lines of code at the maximum. It is one of the greatest free .net libraries out there.
Here is a sample:
string htmlContents = new System.IO.StreamReader(resultsStream,Encoding.UTF8,true).ReadToEnd();
HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(htmlContents);
if (doc == null) return null;
string output = "";
foreach (var node in doc.DocumentNode.ChildNodes)
{
output += node.InnerText;
}

Regex.Replace(htmlText, "<.*?>", string.Empty);

protected string StripHtml(string Txt)
{
return Regex.Replace(Txt, "<(.|\\n)*?>", string.Empty);
}
Protected Function StripHtml(Txt as String) as String
Return Regex.Replace(Txt, "<(.|\n)*?>", String.Empty)
End Function

I've posted this on the asp.net forums, and it still seems to be one of the easiest solutions out there. I won't guarantee it's the fastest or most efficient, but it's pretty reliable.
In .NET you can use the HTML Web Control objects themselves. All you really need to do is insert your string into a temporary HTML object such as a DIV, then use the built-in 'InnerText' to grab all text that is not contained within tags. See below for a simple C# example:
System.Web.UI.HtmlControls.HtmlGenericControl htmlDiv = new System.Web.UI.HtmlControls.HtmlGenericControl("div");
htmlDiv.InnerHtml = htmlString;
String plainText = htmlDiv.InnerText;

I have written a pretty fast method in c# which beats the hell out of the Regex. It is hosted in an article on CodeProject.
Its advantages are, among better performance the ability to replace named and numbered HTML entities (those like & and &203;) and comment blocks replacement and more.
Please read the related article on CodeProject.
Thank you.

For those of you who can't use the HtmlAgilityPack, .NETs XML reader is an option. This can fail on well formatted HTML though so always add a catch with regx as a backup. Note this is NOT fast, but it does provide a nice opportunity for old school step through debugging.
public static string RemoveHTMLTags(string content)
{
var cleaned = string.Empty;
try
{
StringBuilder textOnly = new StringBuilder();
using (var reader = XmlNodeReader.Create(new System.IO.StringReader("<xml>" + content + "</xml>")))
{
while (reader.Read())
{
if (reader.NodeType == XmlNodeType.Text)
textOnly.Append(reader.ReadContentAsString());
}
}
cleaned = textOnly.ToString();
}
catch
{
//A tag is probably not closed. fallback to regex string clean.
string textOnly = string.Empty;
Regex tagRemove = new Regex(#"<[^>]*(>|$)");
Regex compressSpaces = new Regex(#"[\s\r\n]+");
textOnly = tagRemove.Replace(content, string.Empty);
textOnly = compressSpaces.Replace(textOnly, " ");
cleaned = textOnly;
}
return cleaned;
}

string result = Regex.Replace(anytext, #"<(.|\n)*?>", string.Empty);

I've looked at the Regex based solutions suggested here, and they don't fill me with any confidence except in the most trivial cases. An angle bracket in an attribute is all it would take to break, let alone mal-formmed HTML from the wild. And what about entities like &? If you want to convert HTML into plain text, you need to decode entities too.
So I propose the method below.
Using HtmlAgilityPack, this extension method efficiently strips all HTML tags from an html fragment. Also decodes HTML entities like &. Returns just the inner text items, with a new line between each text item.
public static string RemoveHtmlTags(this string html)
{
if (String.IsNullOrEmpty(html))
return html;
var doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(html);
if (doc.DocumentNode == null || doc.DocumentNode.ChildNodes == null)
{
return WebUtility.HtmlDecode(html);
}
var sb = new StringBuilder();
var i = 0;
foreach (var node in doc.DocumentNode.ChildNodes)
{
var text = node.InnerText.SafeTrim();
if (!String.IsNullOrEmpty(text))
{
sb.Append(text);
if (i < doc.DocumentNode.ChildNodes.Count - 1)
{
sb.Append(Environment.NewLine);
}
}
i++;
}
var result = sb.ToString();
return WebUtility.HtmlDecode(result);
}
public static string SafeTrim(this string str)
{
if (str == null)
return null;
return str.Trim();
}
If you are really serious, you'd want to ignore the contents of certain HTML tags too (<script>, <style>, <svg>, <head>, <object> come to mind!) because they probably don't contain readable content in the sense we are after. What you do there will depend on your circumstances and how far you want to go, but using HtmlAgilityPack it would be pretty trivial to whitelist or blacklist selected tags.
If you are rendering the content back to an HTML page, make sure you understand XSS vulnerability & how to prevent it - i.e. always encode any user-entered text that gets rendered back onto an HTML page (> becomes > etc).

For those who are complining about Michael Tiptop's solution not working, here is the .Net4+ way of doing it:
public static string StripTags(this string markup)
{
try
{
StringReader sr = new StringReader(markup);
XPathDocument doc;
using (XmlReader xr = XmlReader.Create(sr,
new XmlReaderSettings()
{
ConformanceLevel = ConformanceLevel.Fragment
// for multiple roots
}))
{
doc = new XPathDocument(xr);
}
return doc.CreateNavigator().Value; // .Value is similar to .InnerText of
// XmlDocument or JavaScript's innerText
}
catch
{
return string.Empty;
}
}

using System.Text.RegularExpressions;
string str = Regex.Replace(HttpUtility.HtmlDecode(HTMLString), "<.*?>", string.Empty);

You can also do this with AngleSharp which is an alternative to HtmlAgilityPack (not that HAP is bad). It is easier to use than HAP to get the text out of a HTML source.
var parser = new HtmlParser();
var htmlDocument = parser.ParseDocument(source);
var text = htmlDocument.Body.Text();
You can take a look at the key features section where they make a case at being "better" than HAP. I think for the most part, it is probably overkill for the current question but still, it is an interesting alternative.

For the second parameter,i.e. keep some tags, you may need some code like this by using HTMLagilityPack:
public string StripTags(HtmlNode documentNode, IList keepTags)
{
var result = new StringBuilder();
foreach (var childNode in documentNode.ChildNodes)
{
if (childNode.Name.ToLower() == "#text")
{
result.Append(childNode.InnerText);
}
else
{
if (!keepTags.Contains(childNode.Name.ToLower()))
{
result.Append(StripTags(childNode, keepTags));
}
else
{
result.Append(childNode.OuterHtml.Replace(childNode.InnerHtml, StripTags(childNode, keepTags)));
}
}
}
return result.ToString();
}
More explanation on this page: http://nalgorithm.com/2015/11/20/strip-html-tags-of-an-html-in-c-strip_html-php-equivalent/

Simply use string.StripHTML();