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• [PHP] preg_replace: replacing using %

  - by Juan

  Hi all, I'm using the function preg_replace but I cannot figure out how to make it work, the function just doesn't seem to work for me. What I'm trying to do is to convert a string into a link if any word contains the % (percentage) character. For instance if I have the string "go to %mysite", I'd like to convert the mysite word into a link. I tried the following... $data = "go to %mysite"; $result = preg_replace('/(^|[\s\.\,\:\;]+)%([A-Za-z0-9]{1,64})/e', '\\1%<a href=#>\\2</a>', $data); ...but it doesn't work. Any help on this would be much appreciated. Thanks Juan

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• How do I distinguish a SharePoint file update as being from a file upload?

  - by ccomet

  In SharePoint, when an item is first added to a document library, it fires the ItemAdded and ItemAdding events as expected. And if you upload the same filename to update the existing file, it will fire off ItemUpdated and ItemUpdating events, likewise as expected. However, I have been unsuccessful at determining whether this kind of action has actually occurred or not. Or, more specifically, I am entirely unable to differentiate between the following: An item is updated because someone uploaded a new file but did nothing to any of the form fields. An item is updated because someone hit "OK" but did nothing to any of the form fields. Is there actually a way to distinguish these kinds of updates? There appears to be nothing in event properties that contains this information, nor in the version history for both the list item and the file itself. I have even tried comparing the files themselves via OpenBinary(), but in both mentioned cases I still get the same result. Thank you in advance for any help!

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• How to set a reference from one object to another?

  - by Tzur Gazit

  Hi, Imagine the obvious model of employees and departments, where each employee must refer to a single department, and each department may have none to many employees. For Employee I have a pointer to Department, and I set its value to the address of the object of the relevant Department. When I try to save the Employee I get an error: 2010-04-07 10:05:22.491 CoreData2[1112:207] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: Department)' I tried, just for testing, to make the reference from Employee to Department optional, but I get the same result. I'm having my first steps in CoreData so please be as clear and simple as you can. Thanks, Tzur.

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• retrieve contact's nickname

  - by TomTasche

  Hello, I want to get the nickname of a contact from addressbook. I start with his phone number, query it and want the nickname (aka alias) as a result. Cursor cur = context.getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.NUMBER + " = " + incomingNumber, null, null); if (cur.moveToFirst()) { Log.e("saymyname", cur.getString(cur.getColumnIndex(ContactsContract.CommonDataKinds.Nickname.NAME))); Log.e("saymyname", cur.getString(cur.getColumnIndex(ContactsContract.CommonDataKinds.Nickname.LABEL))); } Output of the logs is the incomingNumber (first Log.e() ) and null (second Log.e() ), but I want to get the contact's nickname! Thanks Tom

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• How do I return the entire set / array using NSPredicate?

  - by Prairiedogg

  I'm building a carArray and want to filter the contents conditionally, using an NSPredicate, like so: NSPredicate *pred; switch (carType) { case FreeCar: pred = [NSPredicate predicateWithFormat:@"premium = NO"]; break; case PremiumCar: pred = [NSPredicate predicateWithFormat:@"premium = YES"]; break; default: pred = [NSPredicate predicateWithFormat:@"SOME PREDICATE THAT RETURNS EVERYTHING"]; break; } self.carArray = [aCarArrayIGotFromSomewhere filteredArrayUsingPredicate:pred]; My question is, what is the correct syntax for the value I've stubbed in as SOME PREDICATE THAT RETURNS EVERYTHING which returns all of the instances in the array / set? PS - I know the answer and will post it immediately, just sharing it for everyone's reference as an earlier search on SO did not yield the result.

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• QScrollArea widget content promoted to QWidget

  - by ocell

  Hi folks, First of all, thanks for you time reading my question. I created my own Qt Widget (parent of QWidget) and has a QImage "inside" to manipulate images. The problem I have is the following: when I promote the content of a QScrollArea to my widget, the scroll features doesn't works; I haven't any scroll bar or I can't see any result when I use the method 'ensureVisible(..)'. Please can you tell me if I need to overload or override any method in my own widget. Regards and thanks in advance, Oscar.

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• Google Map API V3 geocoder not showing the correct place

  - by TTCG

  I am upgrading my codes from Google Map API V2 to V3. In V2, I used GlocalSearch to get the latitude and longitude for the given address. In V3, I saw google.maps.Geocoder() and try to get the similar detail. However, the lat & long given by the V3 function is not accurate. Pls see the following screenshot here: My codes for V3 are as follow: var geocoder = new google.maps.Geocoder(); function codeAddress(address) { if (geocoder) { address = address + ", UK"; geocoder.geocode( { 'address': address}, function(results, status) { if (status == google.maps.GeocoderStatus.OK) { var latlng = results[0].geometry.location; addMarker(latlng); //Adding Marker here } else { alert("Geocode was not successful for the following reason: " + status); } }); } } Is there better way to get the accurate result in API V3? Thanks.

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• What algorithm can calculate the power set of a given set?

  - by ross

  I would like to efficiently generate a unique list of combinations of numbers based on a starting list of numbers. example start list = [1,2,3,4,5] but the algorithm should work for [1,2,3...n] result = [1],[2],[3],[4],[5] [1,2],[1,3],[1,4],[1,5] [1,2,3],[1,2,4],[1,2,5] [1,3,4],[1,3,5],[1,4,5] [2,3],[2,4],[2,5] [2,3,4],[2,3,5] [3,4],[3,5] [3,4,5] [4,5] Note. I don't want duplicate combinations, although I could live with them, eg in the above example I don't really need the combination [1,3,2] because it already present as [1,2,3]

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• mysql union query

  - by Sergio

  The table that contains information about members has a structure like: id | fname | pic | status -------------------------------------------------- 1 | john | a.jpg | 1 2 | mike | b.jpg | 1 3 | any | c.jpg | 1 4 | jacky | d.jpg | 1 Table for list of friends looks like: myid | date | user ------------------------------- 1 | 01-01-2011 | 4 2 | 04-01-2011 | 3 I want to make a query that will as result print users from "friendlist" table that contains photos and names of that users from "members" table of both, myid (those who adding) and user (those who are added). That table in this example will look like: myid | myidname | myidpic | user | username | userpic | status ----------------------------------------------------------------------------------- 1 | john | a.jpg | 4 | jacky | d.jpg | 1 2 | mike | b.jpg | 3 | any | c.jpg | 1

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• Conditionally execute a task after building a solution with MSBuild + TFS

  - by SoMoS

  Hello, I'm using MSBuild with TFS and I have to build 4 solutions. When the compilation is done I should launch upon to 4 different Exec tasks depending on wherever the compilation was successful or not. I know how to do that with MSBuild alone using targets with conditions using the var $(BuildBreak) because I can do build solution - check result - exec task - build ... but I don't know how to do that with the TFS extensions ... any help will be very appreciated. Thanks mates.

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• Reverse rendering of Urdu fonts

  - by Syed Muhammad Umair

  I am working on a project that is based on Urdu language in Ubuntu platform. I'm using Python language and have almost achieved my task. The problem is that, the Urdu text is rendered in reverse order. For example, consider the word ??? (which means work) consisting of the three letters: ? , ? , and ? The output is rendered in reverse order as ??? consisting of the three letters: ?, ?, and ? When copying this text to Open Office or opening the generated XML file in Firefox, the generated result is absolutely desired. I Am using Python 2.6 IDLE, its working perfect with Windows platform, which clearly shows its not the problem of IDLE. Am working on TKINTER GUI library. How can this problem be solved?

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• PDF text search and split library

  - by Horace Ho

  I am look for a server side PDF library (or command line tool) which can: split a multi-page PDF file into individual PDF files, based on a search result of the PDF file content Examples: Search "Page ???" pattern in text and split the big PDF into 001.pdf, 002,pdf, ... ???.pdf A server program will scan the PDF, look for the search pattern, save the page(s) which match the patten, and save the file in the disk. It will be nice with integration with PHP / Ruby. Command line tool is also acceptable. It will be a server side (linux or win32) batch processing tool. GUI/login is not supported. i18n support will be nice but no required. Thanks~

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• Handling big user IDs returned by FQL in PHP

  - by ggambett

  I'm using FQL to retrieve a list of users from Facebook. For consistency I get the result as JSON. This causes a problem - since the returned JSON encodes the user IDs as numbers, json_decode() converts these numbers to floating point values, because some are too big to fit in an int; of course, I need these IDs as strings. Since json_decode() does its own thing without accepting any behavior flags, I'm at a loss. Any suggestions on how to resolve this?

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• Overwrite Content in PHP fwrite()

  - by Shahmir Javaid

  Is there any way you can overwrite a line in PHP. let me be a little more clearer using examples. My array array{ [DEVICE] => eth0, [IPADDR] => 192.168.0.2, [NETMASK] => 255.255.255.0, [NETWORK] => 192.168.0.0, [BROADCAST] => 255.255.255.255, [GATEWAY] => 192.168.0.1, [ONBOOT] => no } File im overwriting DEVICE=eth0 IPADDR=192.168.200.2 NETMASK=255.255.255.0 NETWORK=192.168.200.0 BROADCAST=255.255.255.255 GATEWAY=192.168.200.1 ONBOOT=no DNS1=195.100.10.1 Result of the File that is rewritten DEVICE=eth0 IPADDR=192.168.0.2 NETMASK=255.255.255.0 NETWORK=192.168.0.0 BROADCAST=255.255.255.255 GATEWAY=192.168.0.1 ONBOOT=no DNS1=195.100.10.1 Note that DNS1=195.100.10.1 Stays in the file becuase it dosent have a key with the value of DNS in our array. Thanks

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• Can someone explain this block of ASP.NET MVC code to me, please?

  - by Pure.Krome

  Hi folks, this is the current code in ASP.NET MVC2 (RTM) System.Web.Mvc.AuthorizeAttribute class :- public virtual void OnAuthorization(AuthorizationContext filterContext) { if (filterContext == null) { throw new ArgumentNullException("filterContext"); } if (this.AuthorizeCore(filterContext.HttpContext)) { HttpCachePolicyBase cache = filterContext.HttpContext.Response.Cache; cache.SetProxyMaxAge(new TimeSpan(0L)); cache.AddValidationCallback( new HttpCacheValidateHandler(this.CacheValidateHandler), null); } else { filterContext.Result = new HttpUnauthorizedResult(); } } so if i'm 'authorized' then do some caching stuff, otherwise throw a 401 Unauthorized response. Question: What does those 3 caching lines do? cheers :)

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• SQL query for getting data in two fields from one column.

  - by AmiT

  I have a table [Tbl1] containing two fields. ID as int And TextValue as nvarchar(max) Suppose there are 7 records. I need a resultset that has two columns Text1 and Text2. The Text1 should have first 4 records and Text2 should have remaining 3 records. [Tbl1] ID | TextValue 1. | Apple 2. | Mango 3. | Orange 4. | Pineapple 5. | Banana 6. | Grapes 7. | Sapota Now, the result-set should have Text1 | Text2 Apple | Banana Mango | Grapes Orange | Sapota Pineapple |

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• Can't enumerate LinQ results with left join

  - by nvtthang

  var itemSet = from item in da.GetList<Models.account>() join file in objFileStorageList on item.account_id equals file.parent_id into objFile from fileItem in objFile.DefaultIfEmpty() where item.company != null && item.company.company_id == 123 orderby item.updatedDate descending select new { Id = item.account_id, RefNo = item.refNo, StartDate = item.StartDate , EndDate = item.EndDate , Comment = item.comment, FileStorageID = fileItem != null ? fileItem.fileStorage_id : -1, Identification = fileItem != null ? fileItem.identifier : null, fileName = fileItem != null ? fileItem.file_nm : null }; It raises error message when I try to enumerate through collection result from Linq query above. LINQ to Entities does not recognize the method 'System.Collections.Generic.IEnumerable1[SCEFramework.Models.fileStorage] DefaultIfEmpty[fileStorage](System.Collections.Generic.IEnumerable1[SCEFramework.Models.fileStorage])' method, and this method cannot be translated into a store expression foreach (var item in itemSet) { string itemRef= item.RefNo; } Please suggest me any solutions. Thanks in advance.

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• Passing variables to callback functions

  - by mickyjtwin

  I am trying to write a jQuery plugin, that can be applied to a selector. Within this plugin, there are multiple calls to webservices, where callback methods are required. The problem I am having is maintaining the current context item in the each loop of the selector. (function($){ $.fn.myMethod = function(){ return this.each(function(){ var c = $(this); $.api.methodToCall("", CallbackFunction); }); }; function CallbackFunction(data, result){ // do stuff based on c } })(jQuery); Normally, you would provide the callback function straight away, which allows me to access c, however within the callback function, there potentially is another api call, so it would start to get messy. Is there any way to do this?

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• Databinding multiple tables linq query to gridview?

  - by Curtis White

  My question is how can I display a linq query in a gridview that has data from multiple tables AND allow the user to edit some of the fields or delete the data from a single table? I'd like to do this with either a linqdatasource or a linq query. I'm aware I can set the e.Result to the query on the selecting event. I've also been able to build a custom databound control for displaying the linq relations (parent.child). However, I'm not sure how I can make this work with delete? I'm thinking I may need to handle the delete event with custom code.

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• Find missing birth days in Apple Addressbook

  - by Felix Ogg

  I am trying to clean the holes out of my Mac address book. As a first step I want to ask all my friends for their birth day, to be able to congratulate them with cheesy Hallmark cards. I need a "group" in my address book, to mailmerge personalized messages from. This is the Applescript I came up with: tell application "Address Book" make new group with properties {name:"No Birthday"} set birthdayPeople to (get every person whose birth date is greater than date "Monday, January 1, 1900 12:00:00 AM") repeat with i from 1 to number of items in people set thePerson to item i of people if not (birthdayPeople contains thePerson) then add thePerson to group "No Birthday" end if end repeat save end tell It breaks, but from the error messages I cannot deduce what is wrong: Result: error "Can’t make «class azf4» id \"05F770BA-7492-436B-9B58-E24F494702F8:ABPerson\" of application \"Address Book\" into type vector." number -1700 from «class azf4» id "05F770BA-7492-436B-9B58-E24F494702F8:ABPerson" to vector (BTW: Did I mention this is my first AppleScript code, EVER? So, if this code can be simplified, or made more elegant, that is welcome too.)

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• Counting problem: possible sudoko tables?

  - by Sorush Rabiee

  Hi, I'm working on a sudoko solver. my method is using a game tree and explore possible permutations for each set of digits by DFS Algorithm. in order to analyzing problem, i want to know what is the count of possible valid and invalid sudoko tables? - a 9*9 table that have 9 one, 9 two, ... , 9 nine. (this isn't exact duplicate by this question) my solution is: 1- First select 9 cells for 1s: (*) 2- and like (1) for other digits (each time, 9 cells will be deleted from remaining available cells): C(81-9,9) , C(81-9*2,9) .... = 3- finally multiply the result by 9! (permutation of 123456789 in (*)) this is not equal to accepted answer of this question but problems are equivalent. what did i do wrong?

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• Fastest way to calculate summary of database field

  - by Jo-wen

  I have a ms-sql table with the following structure: Name nvarchar; Sign nvarchar; Value int example contents: Test1, 'plus', 5 Test1, 'minus', 3 Test2, 'minus', 1 I would like to have totals per "Name". (add when sign = plus, subtract when sign = minus) result: Test1, 2 Test2, -1 I want to show these results (and update them when a new record is added)... and I'm looking for the fastest solution! [sproc? fast-forward cursor? calculate in .net?]

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• Working with strings in C++

  - by Elliot Bonneville

  Hi. I'm working with strings in C++. I recently came across a problem when entering strings. I'm using cin >> string; to get my string as user input. When the user enters a space into the string, the next input is automatically filled out with the remaining letters, or sometimes left blank. As the next input string is often an integer, this will result in an unpleasant bug. What's a good fix for this?

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• .NET Code Evolution

  - by Alois Kraus

  Originally posted on: http://geekswithblogs.net/akraus1/archive/2013/07/24/153504.aspxAt my day job I do look at a lot of code written by other people. Most of the code is quite good and some is even a masterpiece. And there is also code which makes you think WTF… oh it was written by me. Hm not so bad after all. There are many excuses reasons for bad code. Most often it is time pressure followed by not enough ambition (who cares) or insufficient training. Normally I do care about code quality quite a lot which makes me a (perceived) slow worker who does write many tests and refines the code quite a lot because of the design deficiencies. Most of the deficiencies I do find by putting my design under stress while checking for invariants. It does also help a lot to step into the code with a debugger (sometimes also Windbg). I do this much more often when my tests are red. That way I do get a much better understanding what my code really does and not what I think it should be doing. This time I do want to show you how code can evolve over the years with different .NET Framework versions. Once there was  time where .NET 1.1 was new and many C++ programmers did switch over to get rid of not initialized pointers and memory leaks. There were also nice new data structures available such as the Hashtable which is fast lookup table with O(1) time complexity. All was good and much code was written since then. At 2005 a new version of the .NET Framework did arrive which did bring many new things like generics and new data structures. The “old” fashioned way of Hashtable were coming to an end and everyone used the new Dictionary<xx,xx> type instead which was type safe and faster because the object to type conversion (aka boxing) was no longer necessary. I think 95% of all Hashtables and dictionaries use string as key. Often it is convenient to ignore casing to make it easy to look up values which the user did enter. An often followed route is to convert the string to upper case before putting it into the Hashtable. Hashtable Table = new Hashtable(); void Add(string key, string value) { Table.Add(key.ToUpper(), value); } This is valid and working code but it has problems. First we can pass to the Hashtable a custom IEqualityComparer to do the string matching case insensitive. Second we can switch over to the now also old Dictionary type to become a little faster and we can keep the the original keys (not upper cased) in the dictionary. Dictionary<string, string> DictTable = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase); void AddDict(string key, string value) { DictTable.Add(key, value); } Many people do not user the other ctors of Dictionary because they do shy away from the overhead of writing their own comparer. They do not know that .NET has for strings already predefined comparers at hand which you can directly use. Today in the many core area we do use threads all over the place. Sometimes things break in subtle ways but most of the time it is sufficient to place a lock around the offender. Threading has become so mainstream that it may sound weird that in the year 2000 some guy got a huge incentive for the idea to reduce the time to process calibration data from 12 hours to 6 hours by using two threads on a dual core machine. Threading does make it easy to become faster at the expense of correctness. Correct and scalable multithreading can be arbitrarily hard to achieve depending on the problem you are trying to solve. Lets suppose we want to process millions of items with two threads and count the processed items processed by all threads. A typical beginners code might look like this: int Counter; void IJustLearnedToUseThreads() { var t1 = new Thread(ThreadWorkMethod); t1.Start(); var t2 = new Thread(ThreadWorkMethod); t2.Start(); t1.Join(); t2.Join(); if (Counter != 2 * Increments) throw new Exception("Hmm " + Counter + " != " + 2 * Increments); } const int Increments = 10 * 1000 * 1000; void ThreadWorkMethod() { for (int i = 0; i < Increments; i++) { Counter++; } } It does throw an exception with the message e.g. “Hmm 10.222.287 != 20.000.000” and does never finish. The code does fail because the assumption that Counter++ is an atomic operation is wrong. The ++ operator is just a shortcut for Counter = Counter + 1 This does involve reading the counter from a memory location into the CPU, incrementing value on the CPU and writing the new value back to the memory location. When we do look at the generated assembly code we will see only inc dword ptr [ecx+10h] which is only one instruction. Yes it is one instruction but it is not atomic. All modern CPUs have several layers of caches (L1,L2,L3) which try to hide the fact how slow actual main memory accesses are. Since cache is just another word for redundant copy it can happen that one CPU does read a value from main memory into the cache, modifies it and write it back to the main memory. The problem is that at least the L1 cache is not shared between CPUs so it can happen that one CPU does make changes to values which did change in meantime in the main memory. From the exception you can see we did increment the value 20 million times but half of the changes were lost because we did overwrite the already changed value from the other thread. This is a very common case and people do learn to protect their  data with proper locking.   void Intermediate() { var time = Stopwatch.StartNew(); Action acc = ThreadWorkMethod_Intermediate; var ar1 = acc.BeginInvoke(null, null); var ar2 = acc.BeginInvoke(null, null); ar1.AsyncWaitHandle.WaitOne(); ar2.AsyncWaitHandle.WaitOne(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Intermediate did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Intermediate() { for (int i = 0; i < Increments; i++) { lock (this) { Counter++; } } } This is better and does use the .NET Threadpool to get rid of manual thread management. It does give the expected result but it can result in deadlocks because you do lock on this. This is in general a bad idea since it can lead to deadlocks when other threads use your class instance as lock object. It is therefore recommended to create a private object as lock object to ensure that nobody else can lock your lock object. When you read more about threading you will read about lock free algorithms. They are nice and can improve performance quite a lot but you need to pay close attention to the CLR memory model. It does make quite weak guarantees in general but it can still work because your CPU architecture does give you more invariants than the CLR memory model. For a simple counter there is an easy lock free alternative present with the Interlocked class in .NET. As a general rule you should not try to write lock free algos since most likely you will fail to get it right on all CPU architectures. void Experienced() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); t1.Wait(); t2.Wait(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Experienced did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Experienced() { for (int i = 0; i < Increments; i++) { Interlocked.Increment(ref Counter); } } Since time does move forward we do not use threads explicitly anymore but the much nicer Task abstraction which was introduced with .NET 4 at 2010. It is educational to look at the generated assembly code. The Interlocked.Increment method must be called which does wondrous things right? Lets see: lock inc dword ptr [eax] The first thing to note that there is no method call at all. Why? Because the JIT compiler does know very well about CPU intrinsic functions. Atomic operations which do lock the memory bus to prevent other processors to read stale values are such things. Second: This is the same increment call prefixed with a lock instruction. The only reason for the existence of the Interlocked class is that the JIT compiler can compile it to the matching CPU intrinsic functions which can not only increment by one but can also do an add, exchange and a combined compare and exchange operation. But be warned that the correct usage of its methods can be tricky. If you try to be clever and look a the generated IL code and try to reason about its efficiency you will fail. Only the generated machine code counts. Is this the best code we can write? Perhaps. It is nice and clean. But can we make it any faster? Lets see how good we are doing currently. Level Time in s IJustLearnedToUseThreads Flawed Code Intermediate 1,5 (lock) Experienced 0,3 (Interlocked.Increment) Master 0,1 (1,0 for int[2]) That lock free thing is really a nice thing. But if you read more about CPU cache, cache coherency, false sharing you can do even better. int[] Counters = new int[12]; // Cache line size is 64 bytes on my machine with an 8 way associative cache try for yourself e.g. 64 on more modern CPUs void Master() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Master, 0); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Master, Counters.Length - 1); t1.Wait(); t2.Wait(); Counter = Counters[0] + Counters[Counters.Length - 1]; if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Master did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Master(object number) { int index = (int) number; for (int i = 0; i < Increments; i++) { Counters[index]++; } } The key insight here is to use for each core its own value. But if you simply use simply an integer array of two items, one for each core and add the items at the end you will be much slower than the lock free version (factor 3). Each CPU core has its own cache line size which is something in the range of 16-256 bytes. When you do access a value from one location the CPU does not only fetch one value from main memory but a complete cache line (e.g. 16 bytes). This means that you do not pay for the next 15 bytes when you access them. This can lead to dramatic performance improvements and non obvious code which is faster although it does have many more memory reads than another algorithm. So what have we done here? We have started with correct code but it was lacking knowledge how to use the .NET Base Class Libraries optimally. Then we did try to get fancy and used threads for the first time and failed. Our next try was better but it still had non obvious issues (lock object exposed to the outside). Knowledge has increased further and we have found a lock free version of our counter which is a nice and clean way which is a perfectly valid solution. The last example is only here to show you how you can get most out of threading by paying close attention to your used data structures and CPU cache coherency. Although we are working in a virtual execution environment in a high level language with automatic memory management it does pay off to know the details down to the assembly level. Only if you continue to learn and to dig deeper you can come up with solutions no one else was even considering. I have studied particle physics which does help at the digging deeper part. Have you ever tried to solve Quantum Chromodynamics equations? Compared to that the rest must be easy ;-). Although I am no longer working in the Science field I take pride in discovering non obvious things. This can be a very hard to find bug or a new way to restructure data to make something 10 times faster. Now I need to get some sleep ….

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• How does the method overload resolution system decide which method to call when a null value is passed?

  - by Joan Venge

  So for instance you have a type like: public class EffectOptions { public EffectOptions ( params object [ ] options ) {} public EffectOptions ( IEnumerable<object> options ) {} public EffectOptions ( string name ) {} public EffectOptions ( object owner ) {} public EffectOptions ( int count ) {} public EffectOptions ( Point point ) {} } Here I just give the example using constructors but the result will be the same if they were non-constructor methods on the type itself, right? So when you do: EffectOptions options = new EffectOptions (null); which constructor would be called, and why? I could test this myself but I want to understand how the overload resolution system works (not sure if that's what it's called).

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