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Search algorithm for partial words in C#

I'm currently looking for a way to realize a partial word pattern algorithm in C#. The situation I'm in looks like follows:
I got a textfield for the search pattern. Every time the user enters or deletes a char in this field, an event triggers which re-runs the search algorithm. So in case I want to search for the word "face" in strings like
"Facebook", "Facelifting", ""Faceless Face" (whatever that should be) or in generally ANY real life sentences as strings,
the algorithm would first start running when typing "f" in the field. It then show the most relevant String on top of a list the strings are in. The second time it runs when "fa" is typed, and the list is sorted again. This goes on until "face" is completely typed in the textfield and the list is sorted again.
However I don't know what algorithm could be used. I tried the answer from Alain (Getting the closest string match), a simple Levenshtein-Distance algorithm as well as an self-made algorithm, which calculates the priority via
priority = (length_of_typed_pattern) * (amount_of_substr_matches)
In C#, the latter looks like this:
count = Regex.Matches(Regex.Escape(title), pattern).Count;
priority = pattern.Length * count;
The pattern as well as the title are composed of only lowercase letters.
My conclusions so far:
Hamming distance won't make any sense since the strings are not the same length most of the time
The answer from Alain works fine, but only if at least one word completely matches (you only find a most relevant string/sentence when at least one word is equal with the pattern, so if you have "face" typed and there's a string containing the word "facebook", the string containing "facebook" is almost never a top priority
What other ideas could I try? The goal would be to sort the list of strings the best possible way in the earliest moment (with the fewest letters).
You can look at my implementations in the search-* branches of my repository on http://github.com/croemheld/sprung) in Sprung/WindowMatcher.cs and Sprung/Window.cs.
Thanks for your help.

First of all you need to store frequency related to a string(number of times a particular string is searched) in some place to show most relevant one when searched. If you need to show say k most relevant entries so a Min Heap of size 'k' can be implemented.
Case 1- If a letter is pressed for the first time:-
Step (a) Read all the string starting from a Data base or dictionary and store in some data structure(Say DS1) with a FLAG_VALID(set to 1 initially) which shows that it is valid string for the present search characters(for first letter all the strings will be valid).
As you read strings fill the Min Heap according to their Frequency and an element with certain frequency is inserted only when its frequency is greater than minimum one(i.e. the first element of min Heap).
Step (b) (This step is same for all case to show result) To show results you need to show elements in reverse order than Min Heap i.e. first element in Min Heap will have least priority, so basically we need to delete all elements one by one and show it from last to first.
NOTE:- Min Heap will contain reference to a particular string and so the string and its frequency can be accessed at the same time.
Case 2- Inserting next letters in search box:
Step (a) Search through DS1 in which all strings are present and check FLAG_VALID first. If it is a valid string than compare the string from search box and the string from DS1. Set the flag accordingly(if it is a match-1 or not-0) and fill k-Min Heap as it is empty from last search as in Case 1.
Step (b) is as usual.
Case 3- Deleting a letter in search box:
It is similar to above cases but this time we will need to search for those strings also whose FALG_VALID is 0(i.e string which are invalid).
This is a crude searching method and can be improved using certain Data structure and tweaking the algorithm.

Non-Repetitive Random Alphanumeric Code

One of my clients wants to use a unique code for his items (long story..) and he asked me for a solution. The code will consist in 4 parts in which the first one is the zip code where the item is sent from, the second one is the supplier registration number, the third number is the year when the item is sent and the last part is a three division alphanumeric unique character.
As you can see the first three parts are static fields which will never change for the same sender in the same year. So we can say that the last part is the identifier part for that year. This part is 3-division alpahnumeric which means starting from 000 and ending with ZZZ.
The problem is that my client, for some reasonable reasons, wants this part to be not sequential. For example this is not what he wants:
06450-05-2012-000
06450-05-2012-001
06450-05-2012-002
...
06450-05-2012-ZZY
06450-05-2012-ZZZ
The last part should produced randomly like:
06450-05-2012-A17
06450-05-2012-0BF
06450-05-2012-002
...
06450-05-2012-T7W
06450-05-2012-22C
But it should also non-repetitive. So once a possible id is generated the possibility should be discarded from the selection pool.
I am looking for an effective way to do this.
If I only record selected possibilities and check a newly created one against them there is always a worst case possibility that it keeps producing already selected ones, especially near the end.
If I create all possibilities at once and record them in a table or a file it may take a while after every item creation because it will lookup for a non-selected record. By the way 26 letters + 10 digits means 46.656 possible combinations, and there is a chance that there may be a 4th divison added which means 1.679.616 possible combinations.
Is there a more effective way you can suggest? I will use C# for coding and MS SQL for databese..

If it doesn't have to be random, you could maybe simply choose a fixed but "unpredictable" addend which is relatively prime to 26 + 10 == 36 == 2²·3². This means, just choose a fixed addend divisible by neither 2 nor 3.
Then keep adding this fixed number to your previous serial number every time you need a new serial number. This is to be done modulo 46656 (or 1679616) of course.
Mathematics guarantees you won't get the same number twice (before no more "free" numbers are left).
As the addend, you could use const int addend = 26075 since it's 5 modulo 6.

If you expect to create far less than 36^3 entries for each zip-supplier-year tuple, you should probably just pick a random value for the last field and then check to see if it exists, repeating if it does.
Even if you create half of the maximum number of possible entries, new entries still have an expected value of only one failure. Assuming your database is indexed on the overall identifier, this isn't too great a price to pay.
That said, if you expect to use all but a few possible identifiers, then you should probably create all the possible records in advance. It may sounds like a high cost, but each space in memory storing an unused record will eventually store a real record.
I'd expect the first situation is more likely, but if not, or if there's some other combination of the two, please add a comment with some more information and I'll revise my answer.

I think options depend on the amount of the codes that are going to be used:
If you expect to use most of them within a year, then it is better to pre-generate. If done right, lookup should be really fast. And you are going to have 1.679.616 items per year in your DB anyway, so you will have to do such things right.
On the other hand, is it good that you are expecting to use most of them? It may leave you without codes if there are suddenly more items than expected.
If you expect to use only a small amount, then random+existence check might be a way to go, however it is unclear what amount it should be for that to be best (I am pretty sure it is possible to calculate that though).

How to evaluate when two DateTimes are equal to one another

This is the situation: I have a TimePicker in my application. I would like the user to be able select a time with the TimePicker, then the app will send the user a notification at the time entered with the TimePicker. I'm writing an application for Windows Phone in C#. So far, this is my code (I don't that any of this is correct)
DateTime now = DateTime.Now;
DateTime? get = timePicker1.Value;
if (now == get)
{
ShellToast toast = new ShellToast();
toast.Title = "Title";
toast.Content = "The Time Has Come!";
toast.Show();
}
But every time I run the code, it either gives me an exception, the app doesn't load at all, and every time the notification (toast) never shows. (I also know that the app cannot be running in the foreground for the notification to show). (I know that the notification works because I can get it to work with other situations).
Basically, my questions is: how can I trigger a notification at a specific time defined by the end user?

First of all the Toast notification won't show up if the app is running in foreground. It should be only used in background agents or when application is running under lock screen.
Second, if your goal is to show the notification in selected time of day, then you must not compare the DateTime values, but rather the TimeOfDay part. Also make sure user has entered valid value by checking the "get.HasValue"

Line 1 : DateTime now = DateTime.Now;
Line 2 : DateTime? get = timePicker1.Value;
in Line 1 , you get the system current date-time, "now" is date-time and not null.
but in Line 2, "get" is null-able variable and you are getting the timepicker.value and compare date-time with time.
i do not know what exception you have but with 2 extra checking you can have more safe code
null checking for "get"
make sure that in your development environment you can compare date-time with time value.

You have to remember that Date.Now has a full time AND DATE!
So comparing to the get variable you must ignore the Date part, or probably will not work.
Try changing your if to look something like this:
if (get.HasValue && now.TimeOfDay == get.Value.TimeOfDay)
{
// your remaining code
}
Also, the ShellToast class only works with background services, not on foreground apps (check the Remarks here)!
If you want to show a Toast in your app, use the Toast Prompt from Coding4Fun Toolkit.

You could compare the day, month, year values of the two DateTimes. Take minutes and seconds in account, if you want to be more precise (because I don't know on what detail level you want to compare the values).
If you want to be notified at a specific time, try using the Alarm class.

Managing timeseries in c#

I wanted to have your opinion on what is the best way to manage time series in c# according to you. I need to have a 2 dimensions matrix-like with Datetime object as an index of rows (ordered and without duplicate) and each columns would represent the stock value for the relevant Datetime. I would like to know if any of those objects would be able to handle missing data for a date: adding a column or a time serie would add the missing date in the row index and would add "null" or "N/a" for missing values for existing dates.
A lot of stuff are already available in c# compared to c++ and I don't want to miss something obvious.

TeaFiles.Net is a library for time series storage in flat files. As I understand you only want to have the data in memory, in which case you would use a MemoryStream and pass it to the ctor.
// the time series item type
struct Tick
{
public DateTime Time;
public double Price;
public int Volume;
}
// create file and write some values
var ms = new MemoryStream();
using (var tf = TeaFile<Tick>.Create(ms))
{
tf.Write(new Tick { Price = 5, Time = DateTime.Now, Volume = 700 });
tf.Write(new Tick { Price = 15, Time = DateTime.Now.AddHours(1), Volume = 1700 });
// ...
}
ms.Position = 0; // reset the stream
// read typed
using (var tf = TeaFile<Tick>.OpenRead(ms))
{
Tick value = tf.Read();
Console.WriteLine(value);
}
https://github.com/discretelogics/TeaFiles.Net
You can install the library via NuGet packages Manager "TeaFiles.Net"
A vsix sample Project is also available in the VS Gallery.

You could use a mapping between the date and the stock value, such as Dictionary<DateTime, decimal>. This way the dates can be sparse.
If you need the prices of multiple stocks at each date, and not every stock appears for every date, then you could choose between Dictionary<DateTime, Dictionary<Stock, decimal>> and Dictionary<Stock, Dictionary<DateTime, decimal>>, depending on how you want to access the values afterwards (or even both if you don't mind storing the values twice).

The DateTime object in C# is a value Type which means it initializes with its default value and that is Day=1 Month=1 Year=1 Hour=1 Minute=1 Second=1. (or was it hour=12, i am not quite sure).
If I understood you right you need a datastructure that holds DateTime objects that are ordered in some way and when you insert a new object the adjacent dateTime objects will change to retain your order.
In this case I would focus mor on the datastructure than on the dateTime object.
Write a simple class that inherits from Lits<> for example and include the functionality you want on an insert oder delete operation.
Something like:
public class DateTimeList : List<DateTime> {
public void InsertDateTime (int position, DateTime dateTime) {
// insert the new object
this.InsertAt(position, dateTime)
// then take the adjacent objects (take care of integrity checks i.e.
// exists the index/object? in not null ? etc.
DateTime previous = this.ElementAt<DateTime>(position - 1);
// modify the previous DateTime obejct according to your needs.
DateTime next = this.ElementAt<DateTime>(position + 1);
// modify the next DateTime obejct according to your needs.
}
}

As you mentioned in your comment to Marc's answer, I believe the SortedList is a more appropriate structure to hold your time series data.
UPDATE
As zmbq mentioned in his comment to Marc's question, the SortedList is implemented as an array, so if faster insertion/removal times are needed then the SortedDictionary would be a better choice.
See Jon Skeet's answer to this question for an overview of the performance differences.

The is a time series library called TimeFlow, which allows smart creation and handling of time series.
The central TimeSeries class knows its timezone and is internally based on a sorted list of DatimeTimeOffset/Decimal pairs with specific frequency (Minute, Hour, Day, Month or even custom periods). The frequency can be changed during resample operations (e.g. hours -> days). It is also possible to combine time series unsing the standard operators (+,-,*,/) or advanced join operations using cusom methods.
Further more, the TimeFrame class combines multiple time series of same timezone and frequency (similar to pythons DataFrame but restricted to time series) for easier access.
Additional there is the great TimeFlow.Reporting library that provides advanced reporting / visualization (currently Excel and WPF) of time frames.
Disclaimer: I am the creator of these libraries.

how to afix this hhmmss problem

I was doing window services where I'm generating txt files in target path based on some details from a database but I have a problem the service is running too fast!
I was getting same file name in the place of sec variation required so that i can avoid duplicates over there.
code :
using (transactionscope scope = new transactionscope )
{
string nowtime = datetime.now.today.tostring(HHMMss) // it was working fine
}
file should be generates by specific file naming convention !! ex:hhmmss >>> no millisecond
can any one give me exclusive ideas how to face this part?

You can add milliseconds to the filename:
string nowtime = datetime.Now.Today.ToString("HHmmssfff");
See Custom Date and Time Format Strings.
A few notes about the code you posted:
MM is for months, not minutes. You should use lower case mm.
The parameter that ToString takes is a string.
Your code wouldn't compile as it is not correctly cased. Please use code that can be directly used in the future.
Update:
Seeing as you have to use this format, the only other choice is to "slow down" the service.
Adding a:
Thread.Wait(1000);
In the right place (end of loop?) could do the trick.
Alternatively, you can change your code to append to a file if you are still within the same second.

If you are saying that you are creating multiple files with the same name (multiple files in the same second), then I would take the time out to the milliseconds. You can do this with:
DateTime.Today.ToString("HHmmssfff");
The fff denotes the three places to the right of the decimal (thousandths of a second).