using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(?:src|action|href)=[\'""]\K/(?!/)[^\'""]*";
string substitution = @"https://example.com$0";
string input = @"<img src=""/relative/url/img.jpg"" />
<form action=""/"">
<form action=""/contact-us/"">
<a href='/relative/url/'>Note the Single Quote</a>
<img src=""//site.com/protocol-relative-img.jpg"" />
";
Regex regex = new Regex(pattern);
string result = regex.Replace(input, substitution);
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx