using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(?s)<body>\K\s*<tag(?:(?!<inner_block=25>).)+</tag>";
string substitution = @"";
string input = @"<body>
<tag>
<number=1>
<inner_block=5>
</tag>
<tag>
<number=12>
<inner_block=15>
</tag>
<tag>
<number=21>
<inner_block=25>
</tag>
<tag>
<number=29>
<inner_block=35>
</tag>
</body>";
Regex regex = new Regex(pattern);
string result = regex.Replace(input, substitution, 1);
}
}
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