using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"To:( =\?.*\?= )(Cc|Subject):";
string input = @"# Base base
To: =?GB2312?B?s8LR9A==?= , =?GB2312?B?0e7V8buq?= , =?GB2312?B?ts69qNOi?= , =?GB2312?B?wO7RxcX0?= , =?GB2312?B?wfXX07vU?= Cc: =?GB2312?B?wfXA2g==?= , =?GB2312?B?wfW7qNHT?= Subject: =?GB2312?B?u9i4tDogu9i4tDogcGPXqNawvNK9zMrTxrVidWc=?=
# Base base without Cc:
To: =?GB2312?B?s8LR9A==?= , =?GB2312?B?0e7V8buq?= , =?GB2312?B?ts69qNOi?= , =?GB2312?B?wO7RxcX0?= , =?GB2312?B?wfXX07vU?= Subject: =?GB2312?B?u9i4tDogu9i4tDogcGPXqNawvNK9zMrTxrVidWc=?=
# Only one addressee
To: =?GB2312?B?s8LR9A==?= Cc: =?GB2312?B?wfXA2g==?= , =?GB2312?B?wfW7qNHT?= Subject: =?GB2312?B?u9i4tDogu9i4tDogcGPXqNawvNK9zMrTxrVidWc=?=
# Only one addressee without Cc:
To: =?GB2312?B?s8LR9A==?= Subject: =?GB2312?B?u9i4tDogu9i4tDogcGPXqNawvNK9zMrTxrVidWc=?=
";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
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