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  • Makefile issue with compiling a C++ program

    - by Steve
    I recently got MySQL compiled and working on Cygwin, and got a simple test example from online to verify that it worked. The test example compiled and ran successfully. However, when incorporating MySQL in a hobby project of mine it isn't compiling which I believe is due to how the Makefile is setup, I have no experience with Makefiles and after reading tutorials about them, I have a better grasp but still can't get it working correctly. When I try and compile my hobby project I recieve errors such as: Obj/Database.o:Database.cpp:(.text+0x492): undefined reference to `_mysql_insert_id' Obj/Database.o:Database.cpp:(.text+0x4c1): undefined reference to `_mysql_affected_rows' collect2: ld returned 1 exit status make[1]: *** [build] Error 1 make: *** [all] Error 2 Here is my Makefile, it worked with compiling and building the source before I attempted to put in MySQL support into the project. The LIBMYSQL paths are correct, verified by 'mysql_config'. COMPILER = g++ WARNING1 = -Wall -Werror -Wformat-security -Winline -Wshadow -Wpointer-arith WARNING2 = -Wcast-align -Wcast-qual -Wredundant-decls LIBMYSQL = -I/usr/local/include/mysql -L/usr/local/lib/mysql -lmysqlclient DEBUGGER = -g3 OPTIMISE = -O C_FLAGS = $(OPTIMISE) $(DEBUGGER) $(WARNING1) $(WARNING2) -export-dynamic $(LIBMYSQL) L_FLAGS = -lz -lm -lpthread -lcrypt $(LIBMYSQL) OBJ_DIR = Obj/ SRC_DIR = Source/ MUD_EXE = project MUD_DIR = TestP/ LOG_DIR = $(MUD_DIR)Files/Logs/ ECHOCMD = echo -e L_GREEN = \e[1;32m L_WHITE = \e[1;37m L_BLUE = \e[1;34m L_RED = \e[1;31m L_NRM = \e[0;00m DATE = `date +%d-%m-%Y` FILES = $(wildcard $(SRC_DIR)*.cpp) C_FILES = $(sort $(FILES)) O_FILES = $(patsubst $(SRC_DIR)%.cpp, $(OBJ_DIR)%.o, $(C_FILES)) all: @$(ECHOCMD) " Compiling $(L_RED)$(MUD_EXE)$(L_NRM)."; @$(MAKE) -s build build: $(O_FILES) @rm -f $(MUD_EXE) $(COMPILER) -o $(MUD_EXE) $(L_FLAGS) $(O_FILES) @echo " Finished Compiling $(MUD_EXE)."; @chmod g+w $(MUD_EXE) @chmod a+x $(MUD_EXE) @chmod g+w $(O_FILES) $(OBJ_DIR)%.o: $(SRC_DIR)%.cpp @echo " Compiling $@"; $(COMPILER) -c $(C_FLAGS) $< -o $@ .cpp.o: $(COMPILER) -c $(C_FLAGS) $< clean: @echo " Complete compile on $(MUD_EXE)."; @rm -f $(OBJ_DIR)*.o $(MUD_EXE) @$(MAKE) -s build I like the functionality of the Makefile, instead of spitting out all the arguments etc, it just spits out the "Compiling [Filename]" etc. If I add -c to the L_FLAGS then it compiles (I think) but instead spits out stuff like: g++: Obj/Database.o: linker input file unused because linking not done After a full day of trying and research on google, I'm no closer to solving my problem, so I come to you guys to see if you can explain to me why all this is happening and if possible, steps to solve. Regards, Steve

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  • Primary language - C++/Qt, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Good design of mapping Java Domain objects to Tables (using Hibernate)

    - by M. McKenzie
    Hey guys, I have a question that is more in the realm of design, than implementation. I'm also happy for anyone to point out resources for the answer and I'll gladly, research for myself. Highly simplified Java and SQL: Say I have a business domain POJO called 'Picture' with three attributes. class Picture int idPicture String fileName long size Say I have another business domain POJO called "Item" with 3 attributes Class Item int idItem String itemName ArrayList itemPictures These would be a normal simple relationship. You could say that 'Picture' object, will never exist outside an 'Item' object. Assume a picture belongs only to a specific item, but that an item can have multiple pictures Now - using good database design (3rd Normal Form), we know that we should put items and pictures in their own tables. Here is what I assume would be correct. table Item int idItem (primary key) String itemName table Picture int idPicture (primary key) varchar(45) fileName long size int idItem (foreign key) Here is my question: If you are making Hibernate mapping files for these objects. In the data design, your Picture table needs a column to refer to the Item, so that a foreign key relation can be maintained. However,in your business domain objects - your Picture does not hold a reference/attribute to the idItem - and does not need to know it. A java Picture instance is always instantiated inside an Item instance. If you want to know the Item that the Picture belongs to you are already in the correct scope. Call myItem.getIdItem() and myItem.getItemPictures(),and you have the two pieces of information you need. I know that Hibernate tools have a generator that can auto make your POJO's from looking at your database. My problem stems from the fact that I planned out the data design for this experiment/project first. Then when I went to make the domain java objects, I realized that good design dictated that the objects hold other objects in a nested way. This is obviously different from the way that a database schema is - where all objects(tables) are flat and hold no other complex types within them. What is a good way to reconcile this? Would you: (A) Make the hibernate mapping files so that Picture.hbm.xml has a mapping to the POJO parent's idItem Field (if it's even possible) (B) Add an int attribute in the Picture class to refer to the idItem and set it at instantiation, thus simplifying the hbm.xml mapping file by having all table fields as local attributes in the class (C) Fix the database design because it is wrong, dork. I'd truly appreciate any feedback

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  • PHP running as a FastCGI application (php-cgi) - how to issue concurrent requests?

    - by Sbm007
    Some background information: I'm writing my own webserver in Java and a couple of days ago I asked on SO how exactly Apache interfaces with PHP, so I can implement PHP support. I learnt that FastCGI is the best approach (since mod_php is not an option). So I have looked at the FastCGI protocol specification and have managed to write a working FastCGI wrapper for my server. I have tested phpinfo() and it works, in fact all PHP functions seem to work just fine (posting data, sessions, date/time, etc etc). My webserver is able to serve requests concurrently (ie user1 can retrieve file1.html at the same time as user2 requesting some_large_binary_file.zip), it does this by spawning a new Java thread for each user request (terminating when completed or user connection with client is cancelled). However, it cannot deal with 2 (or more) FastCGI requests at the same time. What it does is, it queues them up, so when request 1 is completed immediately thereafter it starts processing request 2. I tested this with 2 PHP pages, one contains sleep(10) and the other phpinfo(). How would I go about dealing with multiple requests as I know it can be done (PHP under IIS runs as FastCGI and it can deal with multiple requests just fine). Some more info: I am coding under windows and my batch file used to execute php-cgi.exe contains: set PHP_FCGI_CHILDREN=8 set PHP_FCGI_MAX_REQUESTS=500 php-cgi.exe -b 9000 But it does not spawn 8 children, the service simply terminates after 500 requests. I have done research and from Wikipedia: Processing of multiple requests simultaneously is achieved either by using a single connection with internal multiplexing (ie. multiple requests over a single connection) and/or by using multiple connections Now clearly the multiple connections isn't working for me, as everytime a client requests something that involves FastCGI it creates a new socket to the FastCGI application, but it does not work concurrently (it queues them up instead). I know that internal multiplexing of FastCGI requests under the same connection is accomplished by issuing each unique FastCGI request with a different request ID. (also see the last 3 paragraphs of 'The Communication Protocol' heading in this article). I have not tested this, but how would I go about implementing that? I take it I need some kind of FastCGI Java thread which contains a Map of some sort and a static function which I can use to add requests to. Then in the Thread's run() function it would have a while loop and for every cycle it would check whether the Map contains new requests, if so it would assign them a request ID and write them to the FastCGI stream. And then wait for input etc etc, As you can see this becomes too complicated. Does anyone know the correct way of doing this? Or any thoughts at all? Thanks very much. Note, if required I can supply the code for my FastCGI wrapper.

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  • Remote Postgresql - extremely slow

    - by Muffinbubble
    Hi, I have setup PostgreSQL on a VPS I own - the software that accesses the database is a program called PokerTracker. PokerTracker logs all your hands and statistics whilst playing online poker. I wanted this accessible from several different computers so decided to installed it on my VPS and after a few hiccups I managed to get it connecting without errors. However, the performance is dreadful. I have done tons of research on 'remote postgresql slow' etc and am yet to find an answer so am hoping someone is able to help. Things to note: The query I am trying to execute is very small. Whilst connecting locally on the VPS, the query runs instantly. While running it remotely, it takes about 1 minute and 30 seconds to run the query. The VPS is running 100MBPS and then computer I'm connecting to it from is on an 8MB line. The network communication between the two is almost instant, I am able to remotely connect fine with no lag whatsoever and am hosting several websites running MSSQL and all the queries run instantly, whether connected remotely or locally so it seems specific to PostgreSQL. I'm running their newest version of the software and the newest compatible version of PostgreSQL with their software. The database is a new database, containing hardly any data and I've ran vacuum/analyze etc all to no avail, I see no improvements. I don't understand how MSSQL can query almost instantly yet PostgreSQL struggles so much. I am able to telnet to the post 5432 on the VPS IP with no problems, and as I say the query does execute it just takes an extremely long time. What I do notice is on the router when the query is running that hardly any bandwidth is being used - but then again I wouldn't expect it to for a simple query but am not sure if this is the issue. I've tried connecting remotely on 3 different networks now (including different routers) but the problem remains. Connecting remotely via another machine via the LAN is instant. I have also edited the postgre conf file to allow for more memory/buffers etc but I don't think this is the problem - what I am asking it to do is very simple - it shouldn't be intensive at all. Thanks, Ricky

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  • how to deal with the position in a c# stream

    - by CapsicumDreams
    The (entire) documentation for the position property on a stream says: When overridden in a derived class, gets or sets the position within the current stream. The Position property does not keep track of the number of bytes from the stream that have been consumed, skipped, or both. That's it. OK, so we're fairly clear on what it doesn't tell us, but I'd really like to know what it in fact does stand for. What is 'the position' for? Why would we want to alter or read it? If we change it - what happens? In a pratical example, I have a a stream that periodically gets written to, and I have a thread that attempts to read from it (ideally ASAP). From reading many SO issues, I reset the position field to zero to start my reading. Once this is done: Does this affect where the writer to this stream is going to attempt to put the data? Do I need to keep track of the last write position myself? (ie if I set the position to zero to read, does the writer begin to overwrite everything from the first byte?) If so, do I need a semaphore/lock around this 'position' field (subclassing, perhaps?) due to my two threads accessing it? If I don't handle this property, does the writer just overflow the buffer? Perhaps I don't understand the Stream itself - I'm regarding it as a FIFO pipe: shove data in at one end, and suck it out at the other. If it's not like this, then do I have to keep copying the data past my last read (ie from position 0x84 on) back to the start of my buffer? I've seriously tried to research all of this for quite some time - but I'm new to .NET. Perhaps the Streams have a long, proud (undocumented) history that everyone else implicitly understands. But for a newcomer, it's like reading the manual to your car, and finding out: The accelerator pedal affects the volume of fuel and air sent to the fuel injectors. It does not affect the volume of the entertainment system, or the air pressure in any of the tires, if fitted. Technically true, but seriously, what we want to know is that if we mash it to the floor you go faster..

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  • A case-insensitive related implementation problem

    - by Robert
    Hi All, I am going through a final refinement posted by the client, which needs me to do a case-insesitive query. I will basically walk through how this simple program works. First of all, in my Java class, I did a fairly simple webpage parsing: title=(String)results.get("title"); doc = docBuilder.parse("http://" + server + ":" + port + "/exist/rest/db/wb/xql/media_lookup.xql?" + "&title=" + title); This Java statement references an XQuery file "media_lookup.xql" which is stored on localhost, and the only parameter we are passing is the string "title". Secondly, let's take at look at that XQuery file: $title := request:get-parameter('title',""), $mediaNodes := doc('/db/wb/portfolio/media_data.xml'), $query := $mediaNodes//media[contains(title,$title)], Then it will evaluate that query. This XQuery will get the "title" parameter that are passes from our Java class, and query the "media_data" xml file stored in the database, which contains a bunch of media nodes with a 'title' element node. As you may expect, this simple query will just match those media nodes whose 'title' element contains a substring of what the value of string 'title' is. So if our 'title' is "Chi", it will return media nodes whose title may be "Chicago" or "Chicken". The refinment request posted by the client is that there should be NO case-sensitivity. The very intuitive way is to modify the XQuery statement by using a lower-case funtion in it, like: $query := $mediaNodes//media[contains(lower-case(title/text(),lower-case($title))], However, the question comes: this modified query will run my machine into memory overflow. Since my "media_data.xml" is quite huge and contains thouands of millions of media nodes, I assume the lower-case() function will run on each of the entries, thus causing the machine to crash. I've talked with some experienced XQuery programmer, and they think I should use an index to solve this problem, and I will definitely research into that. But before that, I am just posting this problem here to get other ideas or any suggestions, do you think any other way may help? for example, could I tweak the Java parse statement to realize the case-insensitivity? Since I think I saw some people did some string concatination by using "contains." in Java before passing it to the server. Any idea or help is welcomed, thanks in advance.

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  • Remote XP -> Win98 WMI Connection

    - by Logan Young
    I've asked this on Technet, but because Win98 is no longer supported, I can't get any decent information, I was hoping there might be some "old school" developers here who might be able to help me. There is an application that we use a lot at work. This application should run 8am-5pm with as little interruption as possible. Most of the computers where this application runs are using Win98, and we have no way to upgrade them because we can't buy new hardware at the moment. My computer is running WinXP, so I thought of a way to make sure that this application runs all the time: The idea I had was to develop a Windows Service that executes a VBScript file that contains a WMI query to get a list of processes from each computer. Each list is then examined, and, depending on whether or not the target application is running, it will either do nothing, or it will execute another VBScript file that contains a WMI query that will be used to start the target application remotely. I later found a way to do this all with 1 VBScript file (see code below) My problem is in the remote connection to the target computers. I've installed WMI Core 1.5 on them, but every time I try the remote connection, I get the following: The remote server is unavailable or does not exist: 'GetObject' VBScript runtime error 800A01CE I've done some research, and all I've found is info about DCOM Config and Windows Firewall, but Win98 doesn't have either of these. ' #### Variables and constants #### Const HIDDEN_WINDOW = 12 Dim T ' #### End Variables and constants #### Main() Sub Main() ' #### Get Process information from WMI Computer = "." Set WMI = GetObject("winmgmts:" & _ "{ImpersonationLevel=Impersonate}!\\" & Computer & "\root\cimv2") Set Settings = WMI.ExecQuery("SELECT * FROM Win32_Process") For Each Process In Settings ' #### If the application is found to be running, set a value to indicate this If Process.Name = "NOTEPAD.EXE" Then T = True End If Next ' #### T will only have a value if the application is not running. We therefore ' #### evaluate it to determine if it has a value or not. If not, start the application If Not T Then 'MsgBox("Application not found.") Set Startup = WMI.Get("Win32_ProcessStartup") Set Config = Startup.SpawnInstance_ Config.ShowWindow = HIDDEN_WINDOW Set Process = GetObject("winmgmts:root\cimv2:Win32_Process") errReturn = Process.Create(_ "C:\Windows\notepad.exe", null, Config, intProcessID) End If End Sub This uses WMI to get the list of processes from the local computer and, if the target application is running, it'll do nothing, otherwise it'll forcefully start the target application. The problem is that this works only if I specify the local comuter, if I target another computer, I get the error mentioned above. Does anyone have any ideas? Thanks in advance for the help!

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  • Show/hide jQuery

    - by Banderdash
    Not much experience with JavaScript, hopefully one of you gurus can help. <div id="themes"> <h2>Research Themes</h2> <ul> <li><a href="">Learn about our approach to the <strong>environment</strong></a><span><a href="#">Expand</a></span></li> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> <li><a href="">Learn about our approach to <strong>human health</strong></a><span><a href="#">Expand</a></span></li> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> <li class="last"><a href="">Learn about our approach to <strong>national defense</strong></a><span><a href="#">Expand</a></span></li> <ul class="tier_2 hide"> <li><a href="">Project name numero uno goes here</a></li> <li><a href="">Project name numero dos goes here</a></li> <li><a href="">Project name numero tres goes here</a></li> </ul> </ul> </div><!-- // end themes --> This is my markup. As you can see under each of the first tier of li's there are ul's with classes of tier_2 and hide. I've been trying to create some simple jQuery that on click will remove the hide class from it's child ul, but at the same time check that no other ul's with class of tier_2 are shown (aka the other's have the hide class). This should keep a visitor from expanding so many items at once that it will make the layout look funky. Just not sure how to accomplish this, any ideas?

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  • Create a Counter within a For-Loop?

    - by Todd Hartman
    I am a novice programmer and apologize upfront for the complicated question. I am trying to create a lexical decision task for experimental research, in which respondents must decide if a series of letters presented on the screen make a "word" or "not a word". Everything works reasonably well except for the bit where I want to randomly select a word (category A) or nonword (category B) for each of 80 trials from a separate input file (input.txt). The randomization works, but some elements from each list (category A or B) are skipped because I have used "round.catIndex = j;" where "j" is a loop for each successive trial. Because some trials randomly select from Category A and other from Category B, "j" does not move successively down the list for each category. Instead, elements from the Category A list may be selected from something like 1, 2, 5, 8, 9, 10, and so on (it varies each time because of the randomization). To make a long story short(!), how do I create a counter that will work within the for-loop for each trial, so that every word and nonword from Category A and B, respectively, will be used for the lexical decision task? Everything I have tried thus far does not work properly or breaks the javascript entirely. Below is my code snippet and the full code is available at http://50.17.194.59/LDT/trunk/LDT.js. Also, the full lexical decision task can be accessed at http://50.17.194.59/LDT/trunk/LDT.php. Thanks! function initRounds() { numlst = []; for (var k = 0; k<numrounds; k++) { if (k % 2 == 0) numlst[k] = 0; else numlst[k] = 1; } numlst.sort(function() {return 0.5 - Math.random()}) for (var j = 0; j<numrounds; j++) { var round = new LDTround(); if (numlst[j] == 0) { round.category = input.catA.datalabel; } else if (numlst[j] == 1) { round.category = input.catB.datalabel; } // pick a category & stimulus if (round.category == input.catA.datalabel) { round.itemtype = input.catA.itemtype; round.correct = 1; round.catIndex = j; } else if (round.category == input.catB.datalabel) { round.itemtype = input.catB.itemtype; round.correct = 2; round.catIndex = j; } roundArray[i].push(round); } return roundArray; }

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  • Primary language - QtC++, C#, Java?

    - by Airjoe
    I'm looking for some input, but let me start with a bit of background (for tl;dr skip to end). I'm an IT major with a concentration in networking. While I'm not a CS major nor do I want to program as a vocation, I do consider myself a programmer and do pretty well with the concepts involved. I've been programming since about 6th grade, started out with a proprietary game creation language that made my transition into C++ at college pretty easy. I like to make programs for myself and friends, and have been paid to program for local businesses. A bit about that- I wrote some programs for a couple local businesses in my senior year in high school. I wrote management systems for local shops (inventory, phone/pos orders, timeclock, customer info, and more stuff I can't remember). It definitely turned out to be over my head, as I had never had any formal programming education. It was a great learning experience, but damn was it crappy code. Oh yeah, by the way, it was all vb6. So, I've used vb6 pretty extensively, I've used c++ in my classes (intro to programming up to algorithms), used Java a little bit in another class (had to write a ping client program, pretty easy) and used Java for some simple Project Euler problems to help learn syntax and such when writing the program for the class. I've also used C# a bit for my own simple personal projects (simple programs, one which would just generate an HTTP request on a list of websites and notify if one responded unexpectedly or not at all, and another which just held a list of things to do and periodically reminded me to do them), things I would've written in vb6 a year or two ago. I've just started using Qt C++ for some undergrad research I'm working on. Now I've had some formal education, I [think I] understand organization in programming a lot better (I didn't even use classes in my vb6 programs where I really should have), how it's important to structure code, split into functions where appropriate, document properly, efficiency both in memory and speed, dynamic and modular programming etc. I was looking for some input on which language to pick up as my "primary". As I'm not a "real programmer", it will be mostly hobby projects, but will include some 'real' projects I'm sure. From my perspective: QtC++ and Java are cross platform, which is cool. Java and C# run in a virtual machine, but I'm not sure if that's a big deal (something extra to distribute, possibly a bit slower? I think Qt would require additional distributables too, right?). I don't really know too much more than this, so I appreciate any help, thanks! TL;DR Am an avocational programmer looking for a language, want quick and straight forward development, liked vb6, will be working with database driven GUI apps- should I go with QtC++, Java, C#, or perhaps something else?

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  • Finding good heuristic for A* search

    - by Martin
    I'm trying to find the optimal solution for a little puzzle game called Twiddle (an applet with the game can be found here). The game has a 3x3 matrix with the number from 1 to 9. The goal is to bring the numbers in the correct order using the minimum amount of moves. In each move you can rotate a 2x2 square either clockwise or counterclockwise. I.e. if you have this state 6 3 9 8 7 5 1 2 4 and you rotate the upper left 2x2 square clockwise you get 8 6 9 7 3 5 1 2 4 I'm using a A* search to find the optimal solution. My f() is simply the number of rotations need. My heuristic function already leads to the optimal solution but I don't think it's the best one you can find. My current heuristic takes each corner, looks at the number at the corner and calculates the manhatten distance to the position this number will have in the solved state (which gives me the number of rotation needed to bring the number to this postion) and sums all these values. I.e. You take the above example: 6 3 9 8 7 5 1 2 4 and this end state 1 2 3 4 5 6 7 8 9 then the heuristic does the following 6 is currently at index 0 and should by at index 5: 3 rotations needed 9 is currently at index 2 and should by at index 8: 2 rotations needed 1 is currently at index 6 and should by at index 0: 2 rotations needed 4 is currently at index 8 and should by at index 3: 3 rotations needed h = 3 + 2 + 2 + 3 = 10 But there is the problem, that you rotate 4 elements at once. So there a rare cases where you can do two (ore more) of theses estimated rotations in one move. This means theses heuristic overestimates the distance to the solution. My current workaround is, to simply excluded one of the corners from the calculation which solves this problem at least for my test-cases. I've done no research if really solves the problem or if this heuristic still overestimates in same edge-cases. So my question is: What is the best heuristic you can come up with? (Disclaimer: This is for a university project, so this is a bit of homework. But I'm free to use any resource if can come up with, so it's okay to ask you guys. Also I will credit Stackoverflow for helping me ;) )

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  • SQL Cartesian product joining table to itself and inserting into existing table

    - by Emma
    I am working in phpMyadmin using SQL. I want to take the primary key (EntryID) from TableA and create a cartesian product (if I am using the term correctly) in TableB (empty table already created) for all entries which share the same value for FieldB in TableA, except where TableA.EntryID equals TableA.EntryID So, for example, if the values in TableA were: TableA.EntryID TableA.FieldB 1 23 2 23 3 23 4 25 5 25 6 25 The result in TableB would be: Primary key EntryID1 EntryID2 FieldD (Default or manually entered) 1 1 2 Default value 2 1 3 Default value 3 2 1 Default value 4 2 3 Default value 5 3 1 Default value 6 3 2 Default value 7 4 5 Default value 8 4 6 Default value 9 5 4 Default value 10 5 6 Default value 11 6 4 Default value 12 6 5 Default value I am used to working in Access and this is the first query I have attempted in SQL. I started trying to work out the query and got this far. I know it's not right yet, as I’m still trying to get used to the syntax and pieced this together from various articles I found online. In particular, I wasn’t sure where the INSERT INTO text went (to create what would be an Append Query in Access). SELECT EntryID FROM TableA.EntryID TableA.EntryID WHERE TableA.FieldB=TableA.FieldB TableA.EntryID<>TableA.EntryID INSERT INTO TableB.EntryID1 TableB.EntryID2 After I've got that query right, I need to do a TRIGGER query (I think), so if an entry changes it's value in TableA.FieldB (changing it’s membership of that grouping to another grouping), the cartesian product will be re-run on THAT entry, unless TableB.FieldD = valueA or valueB (manually entered values). I have been using the Designer Tab. Does there have to be a relationship link between TableA and TableB. If so, would it be two links from the EntryID Primary Key in TableA, one to each EntryID in TableB? I assume this would not work because they are numbered EntryID1 and EntryID2 and the name needs to be the same to set up a relationship? If you can offer any suggestions, I would be very grateful. Research: http://www.fluffycat.com/SQL/Cartesian-Joins/ Cartesian Join example two Q: You said you can have a Cartesian join by joining a table to itself. Show that! Select * From Film_Table T1, Film_Table T2;

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  • PHP problems when transfering code from Windows to OS X

    - by Makka95
    I have recently bought a new MacBook Pro. Before I had my MacBook Pro I was working on a website on my desktop computer. And now I want to transfer this code to my new MacBook Pro. The problem is that when I transfered the code (I put it on Dropbox and simply downloaded it on my MacBook Pro) I started to see lots of error messages in my PHP code. The error message I”m receiving is: Warning: Cannot modify header information - headers already sent by (output started at /some/file.php:1) in /some/file.php on line 23 I have done some research on this and it seems that this error is most frequently caused by a new line, simple whitespace or any output before the <?php sign. I have looked through all the places where I have cookies that are being sent in the HTTP request and also where I'm using the header() function. I haven’t detected any output or whitespace that possibly could interfere and cause this problem. Noteworthy is that the error always says that the output is started at line 1. Which got me thinking if there is some kind of coding differences in the way that the Mac OS X and Windows operating systems handle new lines or white spaces? Or could the Dropbox transfer messed something up? The code on one of the sites(login.php) which produces the error: <?php include "mysql_database.php"; login(); $id = $_SESSION['Loggedin']; setcookie("login", $id, (time()+60*60*24*30)); header('Location: ' . $_SERVER['HTTP_REFERER']); ?> login function: function login() { $connection = connecttodatabase(); $pass = ""; $user = ""; $query = ""; if (isset($_POST['user']) && $_POST['user'] != null) { $user = $_POST['user']; if (isset($_POST['pass']) && $_POST['pass'] != null) { $pass = md5($_POST['pass']); $query = "SELECT ID FROM Anvandare WHERE Nickname='$user' AND Password ='$pass'"; } } if ($query != "") { $id = $connection->query($query); $id = mysqli_fetch_assoc($id); $id = $id['ID']; $_SESSION['Loggedin'] = $id; } closeconnection($connection); } Complete error: Warning: Cannot modify header information - headers already sent by (output started at /Users/name/GitHub/website/login.php:1) in /Users/namn/GitHub/website/login.php on line 9

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  • Correct use of a "for...in" loop in javascript?

    - by jnkrois
    Hello everybody, before I ask my question I wanted to let everybody know that I appreciate the fact that there's always somebody out there willing to help, and on my end I'll try to give back to the community as much as I can. Thanks Now, I would like to get some pointers as to how to properly take advantage of the "for...in" loop in JavaScript, I already did some research and tried a couple things but it is still not clear to me how to properly use it. Let's say I have a random number of "select" tags in an HTML form, and I don't require the user to select an option for all of them, they can leave some untouched if they want. However I need to know if they selected none or at least one. The way I'm trying to find out if the user selected any of them is by using the "for...in" loop. For example: var allSelected = $("select option:selected"); var totalSelected = $("select option:selected").length; The first variable produces an array of all the selected options. The second variable tells me how many selected options I have in the form (select tags could be more than one and it changes every time). Now, in order to see if any has been selected I loop through each element (selected option), and retrieve the "value" attribute. The default "option" tag has a value="0", so if any selected option returns a value greater than 0, I know at least one option has been selected, however it does not have to be in order, this is my loop so far: for(var i = 0; i < totalSelected; i++){ var eachOption = $(allSelected[i]).val(); var defaultValue = 0; if(eachOption == defaultValue){ ...redirect to another page }else if(eachOption > defaultValue){ ... I display an alert } } My problem here is that as soon as the "if" matches a 0 value, it sends the user to the next page without testing the rest of the elements in the array, and the user could have selected the second or third options. What I really want to do is check all the elements in the array and then take the next action, in my mind this is how I could do it, but I'm not getting it right: var randomValue = 25; for(randomValue in allSelected){ var found = true; var notFound = false if(found){ display an alert }else{ redirect to next page } } This loop or the logic I'm using are flawed (I'm pretty sure), what I want to do is test all the elements in the array against a single variable and take the next action accordingly. I hope this makes some sense to you guys, any help would be appreciated. Thanks, JC

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  • My store returns no code id and breaks 404 error. Magento

    - by numerical25
    I know what the issue is but I dont know how to fix it. I just migrated my magento store locally and I guess possibly some data may have been lost when transferring the DB. the DB is very large. Anyhow, when I login to my admin page, I get a 404 error, page was not found. I debugged the issue and got down to the wire. The exception is thrown in Mage/Core/Model/App.php. Line 759 to be exacted. The following is a snippet. Mage/Core/Model/App.php if (empty($this->_stores[$id])) { $store = Mage::getModel('core/store'); /* @var $store Mage_Core_Model_Store */ if (is_numeric($id)) { $store->load($id); // THIS ID IS FROM Mage_Core_Model_App::ADMIN_STORE_ID and its empty which causes the error } elseif (is_string($id)) { $store->load($id, 'code'); } if (!$store->getCode()) { // RETURNS FALSE HERE BECAUSE NO ID Specified $this->throwStoreException(); } $this->_stores[$store->getStoreId()] = $store; $this->_stores[$store->getCode()] = $store; } The store returns null because $id is null so it therefore does not load any model which explains why it returns false when calling getCode() [EDIT] If you want clarification, please ask for more before voting my post down. Remember I am still trying to get help not get neglected. I am using Version 1.4.1.1. When I type in the URL for admin, I get a 404 page. I walked through the code thouroughly and found that the Model MAGE_CORE_MODEL_STORE::getCode(); Returns Null which triggers the exception. and ends the script. I do not have any other detail. I further troubleshooted the issue by checking the database and that is what the screen shot is. Showing that there is infact data in the Code Colunn. So my question is why is the Model returning a empty column when the column clearly has a value. What can I do to further troubleshoot and figure out why its not working [EDIT UPDATE NEW] I did some research. the reason its returning NULL is because the store ID is null being passed Mage::getStoreConfigFlag('web/secure/use_in_adminhtml', Mage_Core_Model_App::ADMIN_STORE_ID); // THIS IS THE ID being specified Mage_Core_Model_App::ADMIN_STORE_ID has no value in it, so this method throws the exception. Not sure why how to fix this.

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  • jquery mouseent/leave to make div appears

    - by Blake
    I am looking to hover over my list item and have an effect similar to something like facebook chat is my best example..I am able to get the first div to appear but I believe this may be a selector issue because I cant get the rest working properly html <ul id="menu_seo" class="menu"> <li id="menu-seo"><span class="arrowout1"></span>SEO</li> <li id="menu-siteaudits"><span class="arrowout2"></span>Site Audits </li> <li id="menu-linkbuilding"><span class="arrowout3"></span>Link-Building</li> <li id="menu-localseo"><span class="arrowout4"></span>Local SEO</li> </ul> <div id="main_content"> <div id="menu-seo-desc"> <p>SEO management begins with a full website diagnosis of current web strategy Adjustments are made to improve your site’s ability to rank higher on search engines and draw more traffic </p> </div> <div id="menu-seo-desc2"> <p>Usability & site architecture review, Search Engine accessibility and indexing, Keyword research & targeting and Conversion rate optimization </p> </div> </div> css #menu-seo-desc { height:125px; width:210px; background-color:red; border-color:#CCC #E8E8E8 #E8E8E8 #CCC; border-style:solid; border-width:1.5px; border-radius:5px; box-shadow: 1px 0 2px 0px #888; -moz-box-shadow: 1px 0 2px 0px #888; -webkit-box-shadow: 1px 0 2px 1px #888; position:absolute; top:220px; left:350px; display:none; } js <script> $(document).ready(function(){ <script> $(document).ready(function(){ $('#menu_seo').on('#menu-seo', { 'mouseenter': function() { $('#menu-seo-desc').fadeIn(600); $('#menu-seo-desc2').fadeIn(600); }, 'mouseleave': function() { $('#menu-seo-desc').fadeOut(300); $('#menu-seo-desc2').fadeOut(300); } }); }); </script> });

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  • Codeigniter: Retrieving data on button click with Ajax

    - by OllyTenerife
    I have a simple webpage which generates a random quote from my database upon refreshing the page. I wish to implement some AJAX and JQuery in order to generate quotes via the button rather than having to refresh the page. I have done some research but I am not sure how to implement this in Codeigniter. My current code is below... Page controller: public function index() { $this->load->model('quote_model', '', TRUE); $data['quotes'] = $this->quote_model->getRandom(); $this->load->view('home', $data); } The view: <?php include ('layout/header.php'); ?> <div class="container-fluid"> <div class="row"> <div class="col-md-4 quote-holder"> <img src="application/assets/alan1.jpg" alt="..." class="img-circle img-responsive"> <br> <blockquote class="text-center"> <p><?php echo $quotes[0]['quote']; ?></p> <footer class="text-center"><?php echo $quotes[0]['character_name']; ?> in <cite title="Source Title"><?php echo $quotes[0]['series_name']; ?></cite></footer> </blockquote> <button type="button" class="btn btn-default center-block">Generate quote</button> </div> </div> <?php include ('layout/footer.php'); ?> Here is the function in the model I am retrieving the data from: function getRandom() { $query = $this->db->query(" SELECT * FROM quotes, characters, series WHERE quotes.series_id = series.series_id AND quotes.character_id = characters.character_id ORDER BY rand() LIMIT 1 "); return $query->result_array(); } Should I simply be using something like this? $("button").click(function(){ $.get( "Page/index", function( data ) { //output data to page element... } });

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  • Split a binary file into chunks c++

    - by L4nce0
    I've been bashing my head against trying to first divide up a file into chunks, for the purpose of sending over sockets. I can read / write a file easily without splitting it into chunks. The code below runs, works, kinda. It will write a textfile and has a garbage character. Which if this was just for txt, no problem. Jpegs aren't working with said garbage. Been at it for a few days, so I've done my research, and it's time to get some help. I do want to stick strictly to binary readers, as this need to handle any file. I've seen a lot of slick examples out there. (none of them worked for me with jpgs) Mostly something along the lines of while(file)... I subscribe to the, if you know the size, use a for-loop, not a while-loop camp. Thank you for the help!! vector<char*> readFile(const char* fn){ vector<char*> v; ifstream::pos_type size; char * memblock; ifstream file; file.open(fn,ios::in|ios::binary|ios::ate); if (file.is_open()) { size = fileS(fn); file.seekg (0, ios::beg); int bs = size/3; // arbitrary. Actual program will use the socket send size int ws = 0; int i = 0; for(i = 0; i < size; i+=bs){ if(i+bs > size) ws = size%bs; else ws = bs; memblock = new char [ws]; file.read (memblock, ws); v.push_back(memblock); } } else{ exit(-4); } return v; } int main(int argc, char **argv) { vector<char*> v = readFile("foo.txt"); ofstream myFile ("bar.txt", ios::out | ios::binary); for(vector<char*>::iterator it = v.begin(); it!=v.end(); ++it ){ myFile.write(*it,strlen(*it)); } }

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  • Why is the page still caching even after the no-cache headers have been sent?

    - by Matthew Grasinger
    I've done a ton of research on this and have asked many people with help and still no success. Here are the details... I'm involved in developing a website that pulls data from various data files, combines them in a temp .csv file, and then is graphed using a popular graphing library: dygraphs. The bulk of the website is written in PHP. The parameters that determine the data that is graphed are stored in the users session, the .csv is named after the users session and available for download, and then the .csv file is written in a script that passes it to the dygraphs object. And we've found, even with the no-cache headers sent: header("Cache-Control: no-cache, must-revalidate"); header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); Many users experience in the middle of a session, (if enough different graphs are generated) the page displaying an older, static rendering of the page (data they had graphed earlier in the session) as if it were cached and loaded instead of getting a new request. It only gets weirder though: I've checked using developer tools in both Firefox and Chrome and both browsers are receiving the no-cache headers just fine; Even when the problem occurs if you view the page source, the source is the correct content (a table/legend is also dynamically created using php, the source shows the correct table, but what is rendered is older content); the page begins to render correctly until the graph is about to be display, and then shows the older content; the older content displays as if it were a completely static overlay--the cached graph does not have the same dynamic features (roll over data point display, zoom and pan, etc.) And it is as if the correct page were somewhere beneath it (the download button for the csv file moves depending on how large the table is. The older, static page does nothing if you click the download .csv button, but if you can manage to find the one in the page beneath it you can click and still download the .csv. The data in the .csv is correct) It is one of the strangest things I've seen in development thus far. Some other relevant facts are that all the problems I've personally experience occurred while I was using Chrome. Non of these symptoms have been reported by Firefox users. IE users have had the same problems (IE users are forced to use chrome frame). I'm at my wits end at this point. We've sent the php headers; we've tried setting the cache profile for php on IIS as "DisableCache" (or whatever); we've tried sending a random query string to the results page; we've tried all the appropriate meta tags--all with no success.

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  • VB.NET IF() Coalesce and “Expression Expected” Error

    - by Jeff Widmer
    I am trying to use the equivalent of the C# “??” operator in some VB.NET code that I am working in. This StackOverflow article for “Is there a VB.NET equivalent for C#'s ?? operator?” explains the VB.NET IF() statement syntax which is exactly what I am looking for... and I thought I was going to be done pretty quickly and could move on. But after implementing the IF() statement in my code I started to receive this error: Compiler Error Message: BC30201: Expression expected. And no matter how I tried using the “IF()” statement, whenever I tried to visit the aspx page that I was working on I received the same error. This other StackOverflow article Using VB.NET If vs. IIf in binding/rendering expression indicated that the VB.NET IF() operator was not available until VS2008 or .NET Framework 3.5.  So I checked the Web Application project properties but it was targeting the .NET Framework 3.5: So I was still not understanding what was going on, but then I noticed the version information in the detailed compiler output of the error page: This happened to be a C# project, but with an ASPX page with inline VB.NET code (yes, it is strange to have that but that is the project I am working on).  So even though the project file was targeting the .NET Framework 3.5, the ASPX page was being compiled using the .NET Framework 2.0.  But why?  Where does this get set?  How does ASP.NET know which version of the compiler to use for the inline code? For this I turned to the web.config.  Here is the system.codedom/compilers section that was in the web.config for this project: <system.codedom>     <compilers>         <compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">             <providerOption name="CompilerVersion" value="v3.5" />             <providerOption name="WarnAsError" value="false" />         </compiler>     </compilers> </system.codedom> Keep in mind that this is a C# web application project file but my aspx file has inline VB.NET code.  The web.config does not have any information for how to compile for VB.NET so it defaults to .NET 2.0 (instead of 3.5 which is what I need). So the web.config needed to include the VB.NET compiler option.  Here it is with both the C# and VB.NET options (I copied the VB.NET config from a new VB.NET Web Application project file).     <system.codedom>         <compilers>             <compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">                 <providerOption name="CompilerVersion" value="v3.5" />                 <providerOption name="WarnAsError" value="false" />             </compiler>       <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" warningLevel="4" type="Microsoft.VisualBasic.VBCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">         <providerOption name="CompilerVersion" value="v3.5"/>         <providerOption name="OptionInfer" value="true"/>         <providerOption name="WarnAsError" value="false"/>       </compiler>     </compilers>     </system.codedom>   So the inline VB.NET code on my aspx page was being compiled using the .NET Framework 2.0 when it really needed to be compiled with the .NET Framework 3.5 compiler in order to take advantage of the VB.NET IF() coalesce statement.  Without the VB.NET web.config compiler option, the default is to compile using the .NET Framework 2.0 and the VB.NET IF() coalesce statement does not exist (at least in the form that I want it in).  FYI, there is an older IF statement in VB.NET 2.0 compiler which is why it is giving me the unusual “Expression Expected” error message – see this article for when VB.NET got the new updated version. EDIT (2011-06-20): I had made a wrong assumption in the first version of this blog post.  After a little more research and investigation I was able to figure out that the issue was in the web.config and not with the IIS App Pool.  Thanks to the comment from James which forced me to look into this again.

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  • TFS 2010 Build Custom Activity for Merging Assemblies

    - by Jakob Ehn
    *** The sample build process template discussed in this post is available for download from here: http://cid-ee034c9f620cd58d.office.live.com/self.aspx/BlogSamples/ILMerge.xaml ***   In my previous post I talked about library builds that we use to build and replicate dependencies between applications in TFS. This is typically used for common libraries and tools that several other application need to reference. When the libraries grow in size over time, so does the number of assemblies. So all solutions that uses the common library must reference all the necessary assemblies that they need, and if we for example do a refactoring and extract some code into a new assembly, all the clients must update their references to reflect these changes, otherwise it won’t compile. To improve on this, we use a tool from Microsoft Research called ILMerge (Download from here). It can be used to merge several assemblies into one assembly that contains all types. If you haven’t used this tool before, you should check it out. Previously I have implemented this in builds using a simple batch file that contains the full command, something like this: "%ProgramFiles(x86)%\microsoft\ilmerge\ilmerge.exe" /target:library /attr:ClassLibrary1.bl.dll /out:MyNewLibrary.dll ClassLibrary1.dll ClassLibrar2.dll ClassLibrary3.dll This merges 3 assemblies (ClassLibrary1, 2 and 3) into a new assembly called MyNewLibrary.dll. It will copy the attributes (file version, product version etc..) from ClassLibrary1.dll, using the /attr switch. For more info on ILMerge command line tool, see the above link. This approach works, but requires a little bit too much knowledge for the developers creating builds, therefor I have implemented a custom activity that wraps the use of ILMerge. This makes it much simpler to setup a new build definition and have the build automatically do the merging. The usage of the activity is then implemented as part of the Library Build process template mentioned in the previous post. For this article I have just created a simple build process template that only performs the ILMerge operation.   Below is the code for the custom activity. To make it compile, you need to reference the ILMerge.exe assembly. /// <summary> /// Activity for merging a list of assembies into one, using ILMerge /// </summary> public sealed class ILMergeActivity : BaseCodeActivity { /// <summary> /// A list of file paths to the assemblies that should be merged /// </summary> [RequiredArgument] public InArgument<IEnumerable<string>> InputAssemblies { get; set; } /// <summary> /// Full path to the generated assembly /// </summary> [RequiredArgument] public InArgument<string> OutputFile { get; set; } /// <summary> /// Which input assembly that the attibutes for the generated assembly should be copied from. /// Optional. If not specified, the first input assembly will be used /// </summary> public InArgument<string> AttributeFile { get; set; } /// <summary> /// Kind of assembly to generate, dll or exe /// </summary> public InArgument<TargetKindEnum> TargetKind { get; set; } // If your activity returns a value, derive from CodeActivity<TResult> // and return the value from the Execute method. protected override void Execute(CodeActivityContext context) { string message = InputAssemblies.Get(context).Aggregate("", (current, assembly) => current + (assembly + " ")); TrackMessage(context, "Merging " + message + " into " + OutputFile.Get(context)); ILMerge m = new ILMerge(); m.SetInputAssemblies(InputAssemblies.Get(context).ToArray()); m.TargetKind = TargetKind.Get(context) == TargetKindEnum.Dll ? ILMerge.Kind.Dll : ILMerge.Kind.Exe; m.OutputFile = OutputFile.Get(context); m.AttributeFile = !String.IsNullOrEmpty(AttributeFile.Get(context)) ? AttributeFile.Get(context) : InputAssemblies.Get(context).First(); m.SetTargetPlatform(RuntimeEnvironment.GetSystemVersion().Substring(0,2), RuntimeEnvironment.GetRuntimeDirectory()); m.Merge(); TrackMessage(context, "Generated " + m.OutputFile); } } [Browsable(true)] public enum TargetKindEnum { Dll, Exe } NB: The activity inherits from a BaseCodeActivity class which is an internal helper class which contains some methods and properties useful for moste custom activities. In this case, it uses the TrackeMessage method for writing to the build log. You either need to remove the TrackMessage method calls, or implement this yourself (which is not very hard… ) The custom activity has the following input arguments: InputAssemblies A list with the (full) paths to the assemblies to merge OutputFile The name of the resulting merged assembly AttributeFile Which assembly to use as the template for the attribute of the merged assembly. This argument is optional and if left blank, the first assembly in the input list is used TargetKind Decides what type of assembly to create, can be either a dll or an exe Of course, there are more switches to the ILMerge.exe, and these can be exposed as input arguments as well if you need it. To show how the custom activity can be used, I have attached a build process template (see link at the top of this post) that merges the output of the projects being built (CommonLibrary.dll and CommonLibrary2.dll) into a merged assembly (NewLibrary.dll). The build process template has the following custom process parameters:   The Assemblies To Merge argument is passed into a FindMatchingFiles activity to located all assemblies that are located in the BinariesDirectory folder after the compilation has been performed by Team Build. Here is the complete sequence of activities that performs the merge operation. It is located at the end of the Try, Compile, Test and Associate… sequence: It splits the AssembliesToMerge parameter and appends the full path (using the BinariesDirectory variable) and then enumerates the matching files using the FindMatchingFiles activity. When running the build, you can see that it merges two assemblies into a new one:     And the merged assembly (and associated pdb file) is copied to the drop location together with the rest of the assemblies:

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  • Week in Geek: US Govt E-card Scam Siphons Confidential Data Edition

    - by Asian Angel
    This week we learned how to “back up photos to Flickr, automate repetitive tasks, & normalize MP3 volume”, enable “stereo mix” in Windows 7 to record audio, create custom papercraft toys, read up on three alternatives to Apple’s flaky iOS alarm clock, decorated our desktops & app docks with Google icon packs, and more. Photo by alexschlegel. Random Geek Links It has been a busy week on the security & malware fronts and we have a roundup of the latest news to help keep you updated. Photo by TopTechWriter.US. US govt e-card scam hits confidential data A fake U.S. government Christmas e-card has managed to siphon off gigabytes of sensitive data from a number of law enforcement and military staff who work on cybersecurity matters, many of whom are involved in computer crime investigations. Security tool uncovers multiple bugs in every browser Michal Zalewski reports that he discovered the vulnerability in Internet Explorer a while ago using his cross_fuzz fuzzing tool and reported it to Microsoft in July 2010. Zalewski also used cross_fuzz to discover bugs in other browsers, which he also reported to the relevant organisations. Microsoft to fix Windows holes, but not ones in IE Microsoft said that it will release two security bulletins next week fixing three holes in Windows, but it is still investigating or working on fixing holes in Internet Explorer that have been reportedly exploited in attacks. Microsoft warns of Windows flaw affecting image rendering Microsoft has warned of a Windows vulnerability that could allow an attacker to take control of a computer if the user is logged on with administrative rights. Windows 7 Not Affected by Critical 0-Day in the Windows Graphics Rendering Engine While confirming that details on a Critical zero-day vulnerability have made their way into the wild, Microsoft noted that customers running the latest iteration of Windows client and server platforms are not exposed to any risks. Microsoft warns of Office-related malware Microsoft’s Malware Protection Center issued a warning this week that it has spotted malicious code on the Internet that can take advantage of a flaw in Word and infect computers after a user does nothing more than read an e-mail. *Refers to a flaw that was addressed in the November security patch releases. Make sure you have all of the latest security updates installed. Unpatched hole in ImgBurn disk burning application According to security specialist Secunia, a highly critical vulnerability in ImgBurn, a lightweight disk burning application, can be used to remotely compromise a user’s system. Hole in VLC Media Player Virtual Security Research (VSR) has identified a vulnerability in VLC Media Player. In versions up to and including 1.1.5 of the VLC Media Player. Flash Player sandbox can be bypassed Flash applications run locally can read local files and send them to an online server – something which the sandbox is supposed to prevent. Chinese auction site touts hacked iTunes accounts Tens of thousands of reportedly hacked iTunes accounts have been found on Chinese auction site Taobao, but the company claims it is unable to take action unless there are direct complaints. What happened in the recent Hotmail outage Mike Schackwitz explains the cause of the recent Hotmail outage. DOJ sends order to Twitter for Wikileaks-related account info The U.S. Justice Department has obtained a court order directing Twitter to turn over information about the accounts of activists with ties to Wikileaks, including an Icelandic politician, a legendary Dutch hacker, and a U.S. computer programmer. Google gets court to block Microsoft Interior Department e-mail win The U.S. Federal Claims Court has temporarily blocked Microsoft from proceeding with the $49.3 million, five-year DOI contract that it won this past November. Google Apps customers get email lockdown Companies and organisations using Google Apps are now able to restrict the email access of selected users. LibreOffice Is the Default Office Suite for Ubuntu 11.04 Matthias Klose has announced some details regarding the replacement of the old OpenOffice.org 3.2.1 packages with the new LibreOffice 3.3 ones, starting with the upcoming Ubuntu 11.04 (Natty Narwhal) Alpha 2 release. Sysadmin Geek Tips Photo by Filomena Scalise. How to Setup Software RAID for a Simple File Server on Ubuntu Do you need a file server that is cheap and easy to setup, “rock solid” reliable, and has Email Alerting? This tutorial shows you how to use Ubuntu, software RAID, and SaMBa to accomplish just that. How to Control the Order of Startup Programs in Windows While you can specify the applications you want to launch when Windows starts, the ability to control the order in which they start is not available. However, there are a couple of ways you can easily overcome this limitation and control the startup order of applications. Random TinyHacker Links Using Opera Unite to Send Large Files A tutorial on using Opera Unite to easily send huge files from your computer. WorkFlowy is a Useful To-do List Tool A cool to-do list tool that lets you integrate multiple tasks in one single list easily. Playing Flash Videos on iOS Devices Yes, you can play flash videos on jailbroken iPhones. Here’s a tutorial. Clear Safari History and Cookies On iPhone A tutorial on clearing your browser history on iPhone and other iOS devices. Monitor Your Internet Usage Here’s a cool, cross-platform tool to monitor your internet bandwidth. Super User Questions See what the community had to say on these popular questions from Super User this week. Why is my upload speed much less than my download speed? Where should I find drivers for my laptop if it didn’t come with a driver disk? OEM Office 2010 without media – how to reinstall? Is there a point to using theft tracking software like Prey on my laptop, if you have login security? Moving an “all-in-one” PC when turned on/off How-To Geek Weekly Article Recap Get caught up on your HTG reading with our hottest articles from this past week. How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk How To Boot 10 Different Live CDs From 1 USB Flash Drive What is Camera Raw, and Why Would a Professional Prefer it to JPG? Did You Know Facebook Has Built-In Shortcut Keys? The How-To Geek Guide to Audio Editing: The Basics One Year Ago on How-To Geek Enjoy looking through our latest gathering of retro article goodness. Learning Windows 7: Create a Homegroup & Join a New Computer To It How To Disconnect a Machine from a Homegroup Use Remote Desktop To Access Other Computers On a Small Office or Home Network How To Share Files and Printers Between Windows 7 and Vista Allow Users To Run Only Specified Programs in Windows 7 The Geek Note That is all we have for you this week and we hope your first week back at work or school has gone very well now that the holidays are over. Know a great tip? Send it in to us at [email protected]. Photo by Pamela Machado. Latest Features How-To Geek ETC HTG Projects: How to Create Your Own Custom Papercraft Toy How to Combine Rescue Disks to Create the Ultimate Windows Repair Disk What is Camera Raw, and Why Would a Professional Prefer it to JPG? The How-To Geek Guide to Audio Editing: The Basics How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 Arctic Theme for Windows 7 Gives Your Desktop an Icy Touch Install LibreOffice via PPA and Receive Auto-Updates in Ubuntu Creative Portraits Peek Inside the Guts of Modern Electronics Scenic Winter Lane Wallpaper to Create a Relaxing Mood Access Your Web Apps Directly Using the Context Menu in Chrome The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video]

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  • C# 4: The Curious ConcurrentDictionary

    - by James Michael Hare
    In my previous post (here) I did a comparison of the new ConcurrentQueue versus the old standard of a System.Collections.Generic Queue with simple locking.  The results were exactly what I would have hoped, that the ConcurrentQueue was faster with multi-threading for most all situations.  In addition, concurrent collections have the added benefit that you can enumerate them even if they're being modified. So I set out to see what the improvements would be for the ConcurrentDictionary, would it have the same performance benefits as the ConcurrentQueue did?  Well, after running some tests and multiple tweaks and tunes, I have good and bad news. But first, let's look at the tests.  Obviously there's many things we can do with a dictionary.  One of the most notable uses, of course, in a multi-threaded environment is for a small, local in-memory cache.  So I set about to do a very simple simulation of a cache where I would create a test class that I'll just call an Accessor.  This accessor will attempt to look up a key in the dictionary, and if the key exists, it stops (i.e. a cache "hit").  However, if the lookup fails, it will then try to add the key and value to the dictionary (i.e. a cache "miss").  So here's the Accessor that will run the tests: 1: internal class Accessor 2: { 3: public int Hits { get; set; } 4: public int Misses { get; set; } 5: public Func<int, string> GetDelegate { get; set; } 6: public Action<int, string> AddDelegate { get; set; } 7: public int Iterations { get; set; } 8: public int MaxRange { get; set; } 9: public int Seed { get; set; } 10:  11: public void Access() 12: { 13: var randomGenerator = new Random(Seed); 14:  15: for (int i=0; i<Iterations; i++) 16: { 17: // give a wide spread so will have some duplicates and some unique 18: var target = randomGenerator.Next(1, MaxRange); 19:  20: // attempt to grab the item from the cache 21: var result = GetDelegate(target); 22:  23: // if the item doesn't exist, add it 24: if(result == null) 25: { 26: AddDelegate(target, target.ToString()); 27: Misses++; 28: } 29: else 30: { 31: Hits++; 32: } 33: } 34: } 35: } Note that so I could test different implementations, I defined a GetDelegate and AddDelegate that will call the appropriate dictionary methods to add or retrieve items in the cache using various techniques. So let's examine the three techniques I decided to test: Dictionary with mutex - Just your standard generic Dictionary with a simple lock construct on an internal object. Dictionary with ReaderWriterLockSlim - Same Dictionary, but now using a lock designed to let multiple readers access simultaneously and then locked when a writer needs access. ConcurrentDictionary - The new ConcurrentDictionary from System.Collections.Concurrent that is supposed to be optimized to allow multiple threads to access safely. So the approach to each of these is also fairly straight-forward.  Let's look at the GetDelegate and AddDelegate implementations for the Dictionary with mutex lock: 1: var addDelegate = (key,val) => 2: { 3: lock (_mutex) 4: { 5: _dictionary[key] = val; 6: } 7: }; 8: var getDelegate = (key) => 9: { 10: lock (_mutex) 11: { 12: string val; 13: return _dictionary.TryGetValue(key, out val) ? val : null; 14: } 15: }; Nothing new or fancy here, just your basic lock on a private object and then query/insert into the Dictionary. Now, for the Dictionary with ReadWriteLockSlim it's a little more complex: 1: var addDelegate = (key,val) => 2: { 3: _readerWriterLock.EnterWriteLock(); 4: _dictionary[key] = val; 5: _readerWriterLock.ExitWriteLock(); 6: }; 7: var getDelegate = (key) => 8: { 9: string val; 10: _readerWriterLock.EnterReadLock(); 11: if(!_dictionary.TryGetValue(key, out val)) 12: { 13: val = null; 14: } 15: _readerWriterLock.ExitReadLock(); 16: return val; 17: }; And finally, the ConcurrentDictionary, which since it does all it's own concurrency control, is remarkably elegant and simple: 1: var addDelegate = (key,val) => 2: { 3: _concurrentDictionary[key] = val; 4: }; 5: var getDelegate = (key) => 6: { 7: string s; 8: return _concurrentDictionary.TryGetValue(key, out s) ? s : null; 9: };                    Then, I set up a test harness that would simply ask the user for the number of concurrent Accessors to attempt to Access the cache (as specified in Accessor.Access() above) and then let them fly and see how long it took them all to complete.  Each of these tests was run with 10,000,000 cache accesses divided among the available Accessor instances.  All times are in milliseconds. 1: Dictionary with Mutex Locking 2: --------------------------------------------------- 3: Accessors Mostly Misses Mostly Hits 4: 1 7916 3285 5: 10 8293 3481 6: 100 8799 3532 7: 1000 8815 3584 8:  9:  10: Dictionary with ReaderWriterLockSlim Locking 11: --------------------------------------------------- 12: Accessors Mostly Misses Mostly Hits 13: 1 8445 3624 14: 10 11002 4119 15: 100 11076 3992 16: 1000 14794 4861 17:  18:  19: Concurrent Dictionary 20: --------------------------------------------------- 21: Accessors Mostly Misses Mostly Hits 22: 1 17443 3726 23: 10 14181 1897 24: 100 15141 1994 25: 1000 17209 2128 The first test I did across the board is the Mostly Misses category.  The mostly misses (more adds because data requested was not in the dictionary) shows an interesting trend.  In both cases the Dictionary with the simple mutex lock is much faster, and the ConcurrentDictionary is the slowest solution.  But this got me thinking, and a little research seemed to confirm it, maybe the ConcurrentDictionary is more optimized to concurrent "gets" than "adds".  So since the ratio of misses to hits were 2 to 1, I decided to reverse that and see the results. So I tweaked the data so that the number of keys were much smaller than the number of iterations to give me about a 2 to 1 ration of hits to misses (twice as likely to already find the item in the cache than to need to add it).  And yes, indeed here we see that the ConcurrentDictionary is indeed faster than the standard Dictionary here.  I have a strong feeling that as the ration of hits-to-misses gets higher and higher these number gets even better as well.  This makes sense since the ConcurrentDictionary is read-optimized. Also note that I tried the tests with capacity and concurrency hints on the ConcurrentDictionary but saw very little improvement, I think this is largely because on the 10,000,000 hit test it quickly ramped up to the correct capacity and concurrency and thus the impact was limited to the first few milliseconds of the run. So what does this tell us?  Well, as in all things, ConcurrentDictionary is not a panacea.  It won't solve all your woes and it shouldn't be the only Dictionary you ever use.  So when should we use each? Use System.Collections.Generic.Dictionary when: You need a single-threaded Dictionary (no locking needed). You need a multi-threaded Dictionary that is loaded only once at creation and never modified (no locking needed). You need a multi-threaded Dictionary to store items where writes are far more prevalent than reads (locking needed). And use System.Collections.Concurrent.ConcurrentDictionary when: You need a multi-threaded Dictionary where the writes are far more prevalent than reads. You need to be able to iterate over the collection without locking it even if its being modified. Both Dictionaries have their strong suits, I have a feeling this is just one where you need to know from design what you hope to use it for and make your decision based on that criteria.

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  • Conversation as User Assistance

    - by ultan o'broin
    Applications User Experience members (Erika Web, Laurie Pattison, and I) attended the User Assistance Europe Conference in Stockholm, Sweden. We were impressed with the thought leadership and practical application of ideas in Anne Gentle's keynote address "Social Web Strategies for Documentation". After the conference, we spoke with Anne to explore the ideas further. Anne Gentle (left) with Applications User Experience Senior Director Laurie Pattison In Anne's book called Conversation and Community: The Social Web for Documentation, she explains how user assistance is undergoing a seismic shift. The direction is away from the old print manuals and online help concept towards a web-based, user community-driven solution using social media tools. User experience professionals now have a vast range of such tools to start and nurture this "conversation": blogs, wikis, forums, social networking sites, microblogging systems, image and video sharing sites, virtual worlds, podcasts, instant messaging, mashups, and so on. That user communities are a rich source of user assistance is not a surprise, but the extent of available assistance is. For example, we know from the Consortium for Service Innovation that there has been an 'explosion' of user-generated content on the web. User-initiated community conversations provide as much as 30 times the number of official help desk solutions for consortium members! The growing reliance on user community solutions is clearly a user experience issue. Anne says that user assistance as conversation "means getting closer to users and helping them perform well. User-centered design has been touted as one of the most important ideas developed in the last 20 years of workplace writing. Now writers can take the idea of user-centered design a step further by starting conversations with users and enabling user assistance in interactions." Some of Anne's favorite examples of this paradigm shift from the world of traditional documentation to community conversation include: Writer Bob Bringhurst's blog about Adobe InDesign and InCopy products and Adobe's community help The Microsoft Development Network Community Center ·The former Sun (now Oracle) OpenDS wiki, NetBeans Ruby and other community approaches to engage diverse audiences using screencasts, wikis, and blogs. Cisco's customer support wiki, EMC's community, as well as Symantec and Intuit's approaches The efforts of Ubuntu, Mozilla, and the FLOSS community generally Adobe Writer Bob Bringhurst's Blog Oracle is not without a user community conversation too. Besides the community discussions and blogs around documentation offerings, we have the My Oracle Support Community forums, Oracle Technology Network (OTN) communities, wiki, blogs, and so on. We have the great work done by our user groups and customer councils. Employees like David Haimes reach out, and enthusiastic non-employee gurus like Chet Justice (OracleNerd), Floyd Teter and Eddie Awad provide great "how-to" information too. But what does this paradigm shift mean for existing technical writers as users turn away from the traditional printable PDF manual deliverables? We asked Anne after the conference. The writer role becomes one of conversation initiator or enabler. The role evolves, along with the process, as the users define their concept of user assistance and terms of engagement with the product instead of having it pre-determined. It is largely a case now of "inventing the job while you're doing it, instead of being hired for it" Anne said. There is less emphasis on formal titles. Anne mentions that her own title "Content Stacker" at OpenStack; others use titles such as "Content Curator" or "Community Lead". However, the role remains one essentially about communications, "but of a new type--interacting with users, moderating, curating content, instead of sitting down to write a manual from start to finish." Clearly then, this role is open to more than professional technical writers. Product managers who write blogs, developers who moderate forums, support professionals who update wikis, rock star programmers with a penchant for YouTube are ideal. Anyone with the product knowledge, empathy for the user, and flair for relationships on the social web can join in. Some even perform these roles already but do not realize it. Anne feels the technical communicator space will move from hiring new community conversation professionals (who are already active in the space through blogging, tweets, wikis, and so on) to retraining some existing writers over time. Our own research reveals that the established proponents of community user assistance even set employee performance objectives for internal content curators about the amount of community content delivered by people outside the organization! To take advantage of the conversations on the web as user assistance, enterprises must first establish where on the spectrum their community lies. "What is the line between community willingness to contribute and the enterprise objectives?" Anne asked. "The relationship with users must be managed and also measured." Anne believes that the process can start with a "just do it" approach. Begin by reaching out to existing user groups, individual bloggers and tweeters, forum posters, early adopter program participants, conference attendees, customer advisory board members, and so on. Use analytical tools to measure the level of conversation about your products and services to show a return on investment (ROI), winning management support. Anne emphasized that success with the community model is dependent on lowering the technical and motivational barriers so that users can readily contribute to the conversation. Simple tools must be provided, and guidelines, if any, must be straightforward but not mandatory. The conversational approach is one where traditional style and branding guides do not necessarily apply. Tools and infrastructure help users to create content easily, to search and find the information online, read it, rate it, translate it, and participate further in the content's evolution. Recognizing contributors by using ratings on forums, giving out Twitter kudos, conference invitations, visits to headquarters, free products, preview releases, and so on, also encourages the adoption of the conversation model. The move to conversation as user assistance is not free, but there is a business ROI. The conversational model means that customer service is enhanced, as user experience moves from a functional to a valued, emotional level. Studies show a positive correlation between loyalty and financial performance (Consortium for Service Innovation, 2010), and as customer experience and loyalty become key differentiators, user experience professionals cannot explore the model's possibilities. The digital universe (measured at 1.2 million petabytes in 2010) is doubling every 12 to 18 months, and 70 percent of that universe consists of user-generated content (IDC, 2010). Conversation as user assistance cannot be ignored but must be embraced. It is a time to manage for abundance, not scarcity. Besides, the conversation approach certainly sounds more interesting, rewarding, and fun than the traditional model! I would like to thank Anne for her time and thoughts, and recommend that all user assistance professionals read her book. You can follow Anne on Twitter at: http://www.twitter.com/annegentle. Oracle's Acrolinx IQ deployment was used to author this article.

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