using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"box(?!-shadow) ";
string input = @"positive lookahead
box(?=-shadow)
https://youtu.be/aIEjh0YsxWA?t=309
// select box only if what comes after it IS -shadow
box-sizing
shape-shadow
------------------------------------------------------------------
negative lookahead
box(?!-shadow)
// select box only if what comes after it IS NOT shadow
box-sizing
shape-shadow
------------------------------------------------------------------
negative look behind
(?<!jeffery).+
https://youtu.be/aIEjh0YsxWA?t=212
// this string cannot come before the @
jeffrey@envato.com
joe@envato.com
------------------------------------------------------------------
positive look behind
(?<=box-)sizing
https://youtu.be/aIEjh0YsxWA?t=337
// only want to select 'sizing' if what comes before it is 'box'
// select sizing as long as what comes before it is 'box'
box-sizing
shape-sizing
------------------------------------------------------------------
negative look behind
(?<!box-)sizing
// anything can come before it except 'box'
box-sizing
shape-sizing
-----------------------------------------------------------------
positive lookahead
@.+(?=\.[a-z]{2,4})
// Matches a group after your main expression without including it in the result
wilson@gmail.com
frank@france.fr
joe@paris.france
";
foreach (Match m in Regex.Matches(input, pattern))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
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