using System;
using System.Globalization;
using System.Linq;
using System.Collections.Generic;

public class Test
{
    

	public static void Main()
	{
        string text = "blub ASP.filename_aspx foo ASP.filename2_aspx bah ...";
        var matches = new List<string>();
        int index = text.IndexOf("ASP", StringComparison.OrdinalIgnoreCase);
        int endIndex = index >= 0 ? text.IndexOf("_aspx", index + 1, StringComparison.OrdinalIgnoreCase) : -1;
        while (index >= 0 && endIndex >= 0)
        {
            index += "ASP.".Length;
            endIndex += "_aspx".Length;
            matches.Add(text.Substring(index, endIndex - index));
            index = text.IndexOf("ASP", endIndex + 1, StringComparison.OrdinalIgnoreCase);
            endIndex = index >= 0 ? text.IndexOf("_aspx", index + 1, StringComparison.OrdinalIgnoreCase) : -1;
        }
        foreach(var str  in matches)
            Console.WriteLine(str);
	}
}