sorted - Page 48 - Developer IT

Writing a recursive sorting algorithm of an array of integers

- by 12345

I am trying to write a recursive sorting algorithm for an array of integers. The following codes prints to the console: 3, 5, 2, 1, 1, 2, 6, 7, 8, 10, 20 The output should be sorted but somehow "it doesn't work". public static void main(String[] args) { int[] unsortedList = {20, 3, 1, 2, 1, 2, 6, 8, 10, 5, 7}; duplexSelectionSort(unsortedList, 0, unsortedList.length-1); for (int i = 0; i < unsortedList.length; i++) { System.out.println(unsortedList[i]); } } public static void duplexSelectionSort( int[] unsortedNumbers, int startIndex, int stopIndex) { int minimumIndex = 0; int maximumIndex = 0; if (startIndex < stopIndex) { int index = 0; while (index <= stopIndex) { if (unsortedNumbers[index] < unsortedNumbers[minimumIndex]) { minimumIndex = index; } if (unsortedNumbers[index] > unsortedNumbers[maximumIndex]) { maximumIndex = index; } index++; } swapEdges(unsortedNumbers, startIndex, stopIndex, minimumIndex, maximumIndex); duplexSelectionSort(unsortedNumbers, startIndex + 1, stopIndex - 1); } } public static void swapEdges( int[] listOfIntegers, int startIndex, int stopIndex, int minimumIndex, int maximumIndex) { if ((minimumIndex == stopIndex) && (maximumIndex == startIndex)) { swap(listOfIntegers, startIndex, stopIndex); } else { if (maximumIndex == startIndex) { swap(listOfIntegers, maximumIndex, stopIndex); swap(listOfIntegers, minimumIndex, startIndex); } else { swap(listOfIntegers, minimumIndex, startIndex); swap(listOfIntegers, maximumIndex, stopIndex); } } } public static void swap(int[] listOfIntegers, int index1, int index2) { int savedElementAtIndex1 = listOfIntegers[index1]; listOfIntegers[index1] = listOfIntegers[index2]; listOfIntegers[index2] = savedElementAtIndex1; }

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Dynamic programming Approach- Knapsack Puzzle

- by idalsin

I'm trying to solve the Knapsack problem with the dynamical programming(DP) approach, with Python 3.x. My TA pointed us towards this code for a head start. I've tried to implement it, as below: def take_input(infile): f_open = open(infile, 'r') lines = [] for line in f_open: lines.append(line.strip()) f_open.close() return lines def create_list(jewel_lines): #turns the jewels into a list of lists jewels_list = [] for x in jewel_lines: weight = x.split()[0] value = x.split()[1] jewels_list.append((int(value), int(weight))) jewels_list = sorted(jewels_list, key = lambda x : (-x[0], x[1])) return jewels_list def dynamic_grab(items, max_weight): table = [[0 for weight in range(max_weight+1)] for j in range(len(items)+1)] for j in range(1,len(items)+1): val= items[j-1][0] wt= items[j-1][1] for weight in range(1, max_weight+1): if wt > weight: table[j][weight] = table[j-1][weight] else: table[j][weight] = max(table[j-1][weight],table[j-1][weight-wt] + val) result = [] weight = max_weight for j in range(len(items),0,-1): was_added = table[j][weight] != table[j-1][weight] if was_added: val = items[j-1][0] wt = items[j-1][1] result.append(items[j-1]) weight -= wt return result def totalvalue(comb): #total of a combo of items totwt = totval = 0 for val, wt in comb: totwt += wt totval += val return (totval, -totwt) if totwt <= max_weight else (0,0) #required setup of variables infile = "JT_test1.txt" given_input = take_input(infile) max_weight = int(given_input[0]) given_input.pop(0) jewels_list = create_list(given_input) #test lines print(jewels_list) print(greedy_grab(jewels_list, max_weight)) bagged = dynamic_grab(jewels_list, max_weight) print(totalvalue(bagged)) The sample case is below. It is in the format line[0] = bag_max, line[1:] is in form(weight, value): 575 125 3000 50 100 500 6000 25 30 I'm confused as to the logic of this code in that it returns me a tuple and I'm not sure what the output tuple represents. I've been looking at this for a while and just don't understand what the code is pointing me at. Any help would be appreciated.

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Get the package of a Java source file

- by Oak

My goal is to find the package (as string) of a Java source file, given as plaintext and not already sorted in folders. I can't just locate the first instance of the keyword package in the file, because it may appear inside a comment. So I was thinking about two alternatives: Scan the file word-by-word, maintaining a "inside-a-comment" flag for the scanner. The first time the package keyword is encountered while not inside a comment, stop the scanning and report the result. Use a regex - should be theoretically possible because block comments do not next in Java, but I tried making such a regex and it turned out to be quite complicated - for me, at least. Another difference between the two approaches is that when scanning manually I can stop the scan when I can be certain the package keyword can no longer appear, saving some time... and I'm not sure I can do something similar with regexes. On the other hand, the decision "when it can no longer appear" is not necessarily simple, though I could use some heuristic for that. I would like to hear any input on this problem, and would welcome any help with the regex. My solution is written in Java as well.

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Run function in current element by get short code inside

- by happi

In stead of adding an ID (IdAddMore) to run script inside ID(widget1) like that : <div class="widget" id="widget1"> <div class="content"> <div id="IdAddMore"></div> <script type='text/javascript'> $("#IdAddMore").selectme({ Numpost:3, Postyle : "Enter your style", }); </script> </div> </div> (widget is added automatically when I add more new widget, It means I can have widget3, widget10, ....Index(3,10..) is any and is not sorted.) Widget is a HTML/JS widget. I want run selectme by short code instead of repeating script in each widget. <div class="widget" id="widget1"> <div class="content"> [3][mystyle] </div> </div> <div class="widget" id="widget50"> <div class="content"> [4][yourstyle] </div> </div> ........... How can I write only script to catch short code in current element is added : I write script below but it does not work. Check for me, thanks your help. <script type='text/javascript'> var getdata = document.getElementsByClassName(".content").innerText || document.getElementById(".content").textContent; var thevalue = []; getdata.replace(/\[(.*?)\]/g, function(g0,g1){thevalue.push(g1);}); $(".widget").selectme({ Numpost:thevalue[0], Postyle: ""+thevalue[1]+"", }); </script>

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List of running minimum values

- by scarle88

Given a sorted list of: new []{1, 2, -1, 3, -2, 1, 1, 2, -1, -3} I want to be able to iterate over the list and at each element return the smallest value iterated so far. So given the list above the resultant list would look like: 1 1 -1 -1 -2 -2 -2 -2 -2 -3 My rough draft code looks like: var items = new []{1, 2, -1, 3, -2, 1, 1, 2, -1, -3}; var min = items.First(); var drawdown = items.Select(i => { if(i < min) { min = i; return i; } else { return min; } }); foreach(var i in drawdown) { Console.WriteLine(i); } But this is not very elegant. Is there an easier to read (linq?) way of doing this? I looked into Aggregate but it seemed to be the wrong tool. Ultimately the list of items will be very long, in the many thousands. So good performance will be an issue to.

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Sorting a table based on which header cell was clicked

- by cf_PhillipSenn

If I have the following: <table> <thead> <tr> <th><a href="Index.cfm?Sort=0">First</a></th> <th><a href="Index.cfm?Sort=1">Second</a></th> <th><a href="Index.cfm?Sort=2">Third</a></th> </tr> </thead> <tbody> <tr> <td>A</td> <td class="num">123</td> <td>XYZ</td> </tr> </tbody> </table> Q: How do I sort the table body based upon which table header cell was clicked? <script> $('th a').click(function() { var $this = $(this).closest('th'); console.log($this.index()); return false; }); </script> (I made each of the table header cells hyperlinks so that if the user has JavaScript turned off, it will follow the link and be sorted on the server side).

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Hanging page loads every n loads - SOLVED

- by Christian

Hi Guys I recently moved my site to a new server (Apache 2, PHP5, MySQL5). The site is an Invision based forum. Every few posts / topics it just hangs. The data has been written because if you stop and reload, the post / thread is there. I thought it was a write issue initially, but nope. So, the data is written but the page load never completes. It doesn't leave the page where the data has been input. Whats the best way to trouble shoot this issue? The only thing I have done recently is reduce my MySQL timeouts, but I can't see that being an issue as the values are still big enough and there are no mentions of timeouts in the MySQL log. (For the record there is nothing in PHP's error log either) Thanks in advance! EDIT: I checked my server-status. It all looked ok, but I have a suspicion I was hitting my ServerLimit, so I doubled that. Also enabled my Keepalives. Will keep an eye on it. EDIT 2: Its now been a few days and this is still occuring. I have more info though; Apache is throwing seg faults, but enabling core dumps does not produce them. I have tried disabling the modules in apache but it just stops things from working. I fear it may actually be DNS related. If I watch Live Headers in Firefox, absolutely nothing happens during this 'hanging' period. After that, the responses come back fairly promptly. UPDATE (05/04): I built the latest versions of Apache and PHP from source, no luck. I then removed those and used the remi repo to update all my packages to the latest stable. Segfaults seem to have stopped, but the hanging is continuing. ini's are at; www.skylinesaustralia.com/php.ini www.skylinesaustralia.com/my.cnf www.skylinesaustralia.com/httpd.conf UPDATE - SOLVED! - The issue was having a gigantic query cache size in MySQL. It was 2GB, changing it to 64M sorted it. Thanks for all the help everybody, much appreciated!!

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UAE and the mysteries of unreachable websites

- by 0plus1

I write here because I'm really lost, please stay with me because it's not easy to explain. A company asked me to set-up a private server, now I'm a programmer so I got a solution with technical support and cpanel which helped me to setup everything and it's working smoothless. I'm by no means a professional sysadmin, but I have a fair knowledge of server configurations, but this problem is way over my knowledge, and apparently way over the knowledge of most sysadmins, I really hope that here I'll find someone with enough experience to help me or at least give me more insight. Now this company for which I'm consulting operates in the UAE (United Arab Emirates) and from there the server is almost unreachable. It started with ns not registering in the UAE, after a week that sorted itself out and now the site is indeed reachable, but it takes almost 2 minutes to load a webpage with one line of text. Emails go in timeout. The domain currently parked there has been bought appositely for tests, the main one that was supposed to go there, after a catastrophic week has been transferred to a shared hosting solution in the UK, and from there it works like a charme. Now after doing some research I discovered that I'm not alone in this, there are several reports of webmasters discovering that their website is not reachable inside the UAE, and mind this has nothing to do with the state-wide block of questionable sites, because in that case an error message appears, this seems to be related to the infrastructure of the UAE, which apparently reroutes everything through their own "fake" internet. Apparently new servers with their own IP are not recognized (yet?) by the UAE infrastructure, while shared hosting solutions seeing that they operates tons of other websites are more likely to be part of the UAE network. Now my questions are: 1) Has someone a real explanation for this? The only thing I can think of is that the server is on a new IP that is not yet recognized by the UAE, but that doesn't explain why it loads (even if after 2 minutes). I don't have any help from within the UAE as the only people that are "experts" are questionable companies that simply try to sell their own services. 2) If there is really some kind of block of new servers, is it possible to know before if a server is reachable from within the UAE, currently this is not a ns problem as even accessing the server with its IP result in a 2 minute wait. 3) Can it be that the problem lies somewhere else? There are some tests that I can perform? I'm not physically in the UAE, but I can ask the people there, or use teamviewer. Could it be some misconfiguration on the server (mind that the site works EVERYWHERE else in the world). Thank you for ANY kind of help

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Plesk Postfix Mail Server 9.5.4 very heavy load, 1000s of processes

- by Eugene van der Merwe

Our Plesk Linux Ubuntu 64-bit mail server has extremely high load and we don't know how to isolate it. The load was okay will two weeks ago but in the last two weeks it's seriously deteriorated. The mail server has been running for years and we have had sporadic performance issues. Normally we reduce the load by turning off all SPAM checks until the problem is sorted (which sometimes resolves itself). Currently we have turned of real time block lists, SPF checking and we have attempted to turn off SpamAssassin. No matter what we do the SpamAssassin check box stays ticked in the GUI. Out of desperation we have done /etc/init.d/psa-spamassassin stop. For years we haven't been able to do SpamAssassin because it kills the server. We would like to use it but performance is more important for now. We cannot turn off Greylisting. The moment we turn off Greylisting our help desk is inandated with calls. Out of desperation we investigated truncating the Greylisting database which is now 2.5 GB big but we abandoned this after noticing turning of Greylisting doesn't improve the performance at all. We have no anti-virus. It's just more load and Dr. Web never really worked that well for us. But we'll try that if it will make a difference. We have implemented Postfix Anvil. This seems to have made the situation worse so we disabled it. We’re not sure if this is the case. Our current mail server is configured to forward all SMTP to a relay server. We did so to reduce the load. This helped a lot because outgoing queues are generally empty. We are running in an Expand configuration. The mail server has about 12 000 accounts of which maybe half are active. We have read through this document: http://www.postfix.org/STRESS_README.html but there are too many settings and we don’t know which ones to choose. Please assist urgently. We need advice on how to fix this problem before all our clients abandon is. The only clue we have is that there are 100s of these processes: 30 13205 1 0 13:18 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10027 before-queue 30 13207 1 0 11:38 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10027 before-queue 30 13208 1 0 13:18 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10026 before-remote 30 13209 1 0 11:38 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10026 before-remote 30 13213 1 0 13:18 ? 00:00:00 /usr/lib/plesk-9.0/postfix-queue 127.0.0.1 10027 before-queue

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Seeking past end of file causes Apache hang, and it never restarts.

- by talkingnews

I've actually solved my problem with a better script, but I'm still left wondering why Apache2 hung completely - this is an out-of-the-box ISPCONFIG 3.03 install, everything bang up to date, running perfectly. Until... The troublesome but innocent-looking script: $fp = fopen("/var/log/ispconfig/cron.log", "r"); fseek($fp, -5000, SEEK_END); $line_buffer = array(); while (!feof($fp)) { $line = fgets($fp, 1024); $line_buffer[] = $line; $line_buffer = array_slice($line_buffer, -10, 10); } foreach ($line_buffer as $line) { echo $line; } You get the idea, just a script I found on a forum somwehere. I did this for various logs, since it's a nice easy window on what's occurring (in a protect dir, of course!). One day, the logs having grown large an me having sorted all my cron, scripting and mail queue errors, I thought I was time to start afresh. updated, rebooted, archived and deleted the logs. When I ran my script a couple of hours later, it hung. And hung. 8 minutes I waited. Chrome timed the page out, of course, but the server never came back to life. htop showed /usr/sbin/apache2 -k restart using 100% CPU. Never came back until I did a service apache2 restart. Ran fine, as soon as I hit that logfile again...dead. So, I worked out it was the logfile script, and I worked out that seeking beyond the end of the file wasn't good, and I found a better script http://www.php.net/manual/en/function.fseek.php#90450 But what I'm left wondering is... why didn't something restart or kill the process? How was one hanging page able to bring down the whole server? It's running suphp. I say "out of the box", I've tweaked mysql and apache to fork and reserve sensible amounts of processes for the 512Mb RAM the VPS has, and it'll handle multiple refreshes of large pages, and hadn't hung before. Any ideas how I'd avoid this? Google isn't my friend in this instance beyond the reccs. above about number of processes vs RAM available.

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Vista stuck at "Shutting down..." screen. Any way to get verbose logging?

- by CapBBeard

Hi all, My home machine has been running fine for about 3 years, no problems at all. Within the last couple of weeks it's had real trouble trying to shut down. It'll get so far and then just sit there at the "Shutting down..." screen for hours. I've left it overnight, I've tried in safe mode, all to no avail. These days, I just wait for the disk activity to finish up and then hold the power button to turn it off. Feels dirty as, especially because there's a RAID involved! The hardware itself is in pretty good shape and of decent spec; Core 2 Quad, 4GB RAM, 1TB RAID 1+0, so it's not quite like a 7 year old PC coming to end of life! In the last month, hardware hasn't changed except for a new monitor. Admittedly I haven't tried unplugging the monitor but I've never heard of that preventing a shutdown. I might give it a whirl later I guess, as a last resort. I've uninstalled old apps, done updates, checked the event log, looked in device manager, uninstalled all non-present devices, disabled various non-critical devices (imaging, audio etc), unplugged peripherals, stopped non-essential services, unplugged the network, disabled the network adapter entirely, ran chkdsk, verified my RAID, the list goes on. But not a single lead. I'm pretty stumped. It could be hardware, but I have no other evidence to suggest so; when the PC is running, it runs fine. Temperatures are good, gaming is smooth as always, disk performance is fine. Event log even makes it look like the shutdown was completed (gets to the point where the event log service stops). In fact, the PC doesn't appear to realise that I cut the power to it. So my question is, does anyone know if there is a way I can get some verbose output (or a log) from shutdown to give me some idea of what is causing the issue? I'm guessing it's stuck unloading some app/driver but it would be good to get some specifics! Unless anyone has any other ideas? I suspect a reinstall would resolve the issue, however I'm looking to get a new PC built in the next month or so, and the reinstall is going to be quite a big job so I'd rather just wait until then if it comes to that. Would still be nice to get this sorted in the mean time though. Cheers!

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file doesn't open, running outside of debugger results in seg fault (c++)

- by misterich

Hello (and thanks in advance) I'm in a bit of a quandry, I cant seem to figure out why I'm seg faulting. A couple of notes: It's for a course -- and sadly I am required to use use C-strings instead of std::string. Please dont fix my code (I wont learn that way and I will keep bugging you). please just point out the flaws in my logic and suggest a different function/way. platform: gcc version 4.4.1 on Suse Linux 11.2 (2.6.31 kernel) Here's the code main.cpp: // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <cstdlib> /// EXIT_SUCCESS, EXIT_FAILURE #include <iostream> /// cin, cout, ifstream #include <cassert> /// assert // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header for the dictionary class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR CONSTANTS #define ENTER '\n' /// Used to accept new lines, quit program. #define SPACE ' ' /// One way to end the program // /////////////////////////////////////////////////////////////////////////////////// // CUSTOM DATA TYPES /// File Namespace -- keep it local namespace { /// Possible program prompts to display for the user. enum FNS_Prompts { fileName_, /// prints out the name of the file noFile_, /// no file was passed to the program tooMany_, /// more than one file was passed to the program noMemory_, /// Not enough memory to use the program usage_, /// how to use the program word_, /// ask the user to define a word. notFound_, /// the word is not in the dictionary done_, /// the program is closing normally }; } // /////////////////////////////////////////////////////////////////////////////////// // Namespace using namespace std; /// Nothing special in the way of namespaces // /////////////////////////////////////////////////////////////////////////////////// // FUNCTIONS /** prompt() prompts the user to do something, uses enum Prompts for parameter. */ void prompt(FNS_Prompts msg /** determines the prompt to use*/) { switch(msg) { case fileName_ : { cout << ENTER << ENTER << "The file name is: "; break; } case noFile_ : { cout << ENTER << ENTER << "...Sorry, a dictionary file is needed. Try again." << endl; break; } case tooMany_ : { cout << ENTER << ENTER << "...Sorry, you can only specify one dictionary file. Try again." << endl; break; } case noMemory_ : { cout << ENTER << ENTER << "...Sorry, there isn't enough memory available to run this program." << endl; break; } case usage_ : { cout << "USAGE:" << endl << " lookup.exe [dictionary file name]" << endl << endl; break; } case done_ : { cout << ENTER << ENTER << "like Master P says, \"Word.\"" << ENTER << endl; break; } case word_ : { cout << ENTER << ENTER << "Enter a word in the dictionary to get it's definition." << ENTER << "Enter \"?\" to get a sorted list of all words in the dictionary." << ENTER << "... Press the Enter key to quit the program: "; break; } case notFound_ : { cout << ENTER << ENTER << "...Sorry, that word is not in the dictionary." << endl; break; } default : { cout << ENTER << ENTER << "something passed an invalid enum to prompt(). " << endl; assert(false); /// something passed in an invalid enum } } } /** useDictionary() uses the dictionary created by createDictionary * - prompts user to lookup a word * - ends when the user enters an empty word */ void useDictionary(Dictionary &d) { char *userEntry = new char; /// user's input on the command line if( !userEntry ) // check the pointer to the heap { cout << ENTER << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } do { prompt(word_); // test code cout << endl << "----------------------------------------" << endl << "Enter something: "; cin.getline(userEntry, INPUT_LINE_MAX_LEN, ENTER); cout << ENTER << userEntry << endl; }while ( userEntry[0] != NIL && userEntry[0] != SPACE ); // GARBAGE COLLECTION delete[] userEntry; } /** Program Entry * Reads in the required, single file from the command prompt. * - If there is no file, state such and error out. * - If there is more than one file, state such and error out. * - If there is a single file: * - Create the database object * - Populate the database object * - Prompt the user for entry * main() will return EXIT_SUCCESS upon termination. */ int main(int argc, /// the number of files being passed into the program char *argv[] /// pointer to the filename being passed into tthe program ) { // EXECUTE /* Testing code * / char tempFile[INPUT_LINE_MAX_LEN] = {NIL}; cout << "enter filename: "; cin.getline(tempFile, INPUT_LINE_MAX_LEN, '\n'); */ // uncomment after successful debugging if(argc <= 1) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// no file was passed to the program } else if(argc > 2) { prompt(tooMany_); prompt(usage_); return EXIT_FAILURE; /// more than one file was passed to the program } else { prompt(fileName_); cout << argv[1]; // print out name of dictionary file if( !argv[1] ) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// file does not exist } /* file.open( argv[1] ); // open file numEntries >> in.getline(file); // determine number of dictionary objects to create file.close(); // close file Dictionary[ numEntries ](argv[1]); // create the dictionary object */ // TEMPORARY FILE FOR TESTING!!!! //Dictionary scrabble(tempFile); Dictionary scrabble(argv[1]); // creaate the dicitonary object //*/ useDictionary(scrabble); // prompt the user, use the dictionary } // exit return EXIT_SUCCESS; /// terminate program. } Dict.h/.cpp #ifndef DICT_H #define DICT_H // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (Custom header files) #include "entry.h" /// class for dictionary entries // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define INPUT_LINE_MAX_LEN 256 /// Maximum length of each line in the dictionary file class Dictionary { public : // // Do NOT modify the public section of this class // typedef void (*WordDefFunc)(const char *word, const char *definition); Dictionary( const char *filename ); ~Dictionary(); const char *lookupDefinition( const char *word ); void forEach( WordDefFunc func ); private : // // You get to provide the private members // // VARIABLES int m_numEntries; /// stores the number of entries in the dictionary Entry *m_DictEntry_ptr; /// points to an array of class Entry // Private Functions }; #endif ----------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <iostream> /// cout, getline #include <fstream> // ifstream #include <cstring> /// strchr // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header file required by assignment //#include "entry.h" /// Dicitonary Entry Class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define COMMA ',' /// Delimiter for file #define ENTER '\n' /// Carriage return character #define FILE_ERR_MSG "The data file could not be opened. Program will now terminate." #pragma warning(disable : 4996) /// turn off MS compiler warning about strcpy() // /////////////////////////////////////////////////////////////////////////////////// // Namespace reference using namespace std; // /////////////////////////////////////////////////////////////////////////////////// // PRIVATE MEMBER FUNCTIONS /** * Sorts the dictionary entries. */ /* static void sortDictionary(?) { // sort through the words using qsort } */ /** NO LONGER NEEDED?? * parses out the length of the first cell in a delimited cell * / int getWordLength(char *str /// string of data to parse ) { return strcspn(str, COMMA); } */ // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC MEMBER FUNCTIONS /** constructor for the class * - opens/reads in file * - creates initializes the array of member vars * - creates pointers to entry objects * - stores pointers to entry objects in member var * - ? sort now or later? */ Dictionary::Dictionary( const char *filename ) { // Create a filestream, open the file to be read in ifstream dataFile(filename, ios::in ); /* if( dataFile.fail() ) { cout << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } */ if( dataFile.is_open() ) { // read first line of data // TEST CODE in.getline(dataFile, INPUT_LINE_MAX_LEN) >> m_numEntries; // TEST CODE char temp[INPUT_LINE_MAX_LEN] = {NIL}; // TEST CODE dataFile.getline(temp,INPUT_LINE_MAX_LEN,'\n'); dataFile >> m_numEntries; /** Number of terms in the dictionary file * \todo find out how many lines in the file, subtract one, ingore first line */ //create the array of entries m_DictEntry_ptr = new Entry[m_numEntries]; // check for valid memory allocation if( !m_DictEntry_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // loop thru each line of the file, parsing words/def's and populating entry objects for(int EntryIdx = 0; EntryIdx < m_numEntries; ++EntryIdx) { // VARIABLES char *tempW_ptr; /// points to a temporary word char *tempD_ptr; /// points to a temporary def char *w_ptr; /// points to the word in the Entry object char *d_ptr; /// points to the definition in the Entry int tempWLen; /// length of the temp word string int tempDLen; /// length of the temp def string char tempLine[INPUT_LINE_MAX_LEN] = {NIL}; /// stores a single line from the file // EXECUTE // getline(dataFile, tempLine) // get a "word,def" line from the file dataFile.getline(tempLine, INPUT_LINE_MAX_LEN); // get a "word,def" line from the file // Parse the string tempW_ptr = tempLine; // point the temp word pointer at the first char in the line tempD_ptr = strchr(tempLine, COMMA); // point the def pointer at the comma *tempD_ptr = NIL; // replace the comma with a NIL ++tempD_ptr; // increment the temp def pointer // find the string lengths... +1 to account for terminator tempWLen = strlen(tempW_ptr) + 1; tempDLen = strlen(tempD_ptr) + 1; // Allocate heap memory for the term and defnition w_ptr = new char[ tempWLen ]; d_ptr = new char[ tempDLen ]; // check memory allocation if( !w_ptr && !d_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // copy the temp word, def into the newly allocated memory and terminate the strings strcpy(w_ptr,tempW_ptr); w_ptr[tempWLen] = NIL; strcpy(d_ptr,tempD_ptr); d_ptr[tempDLen] = NIL; // set the pointers for the entry objects m_DictEntry_ptr[ EntryIdx ].setWordPtr(w_ptr); m_DictEntry_ptr[ EntryIdx ].setDefPtr(d_ptr); } // close the file dataFile.close(); } else { cout << ENTER << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } } /** * cleans up dynamic memory */ Dictionary::~Dictionary() { delete[] m_DictEntry_ptr; /// thou shalt not have memory leaks. } /** * Looks up definition */ /* const char *lookupDefinition( const char *word ) { // print out the word ---- definition } */ /** * prints out the entire dictionary in sorted order */ /* void forEach( WordDefFunc func ) { // to sort before or now.... that is the question } */ Entry.h/cpp #ifndef ENTRY_H #define ENTRY_H // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C++ Std lib) #include <cstdlib> /// EXIT_SUCCESS, NULL // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define NIL '\0' /// C-String terminator #define MEM_ERR_MSG "Memory allocation has failed. Program will now terminate." // /////////////////////////////////////////////////////////////////////////////////// // CLASS DEFINITION class Entry { public: Entry(void) : m_word_ptr(NULL), m_def_ptr(NULL) { /* default constructor */ }; void setWordPtr(char *w_ptr); /// sets the pointer to the word - only if the pointer is empty void setDefPtr(char *d_ptr); /// sets the ponter to the definition - only if the pointer is empty /// returns what is pointed to by the word pointer char getWord(void) const { return *m_word_ptr; } /// returns what is pointed to by the definition pointer char getDef(void) const { return *m_def_ptr; } private: char *m_word_ptr; /** points to a dictionary word */ char *m_def_ptr; /** points to a dictionary definition */ }; #endif -------------------------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "entry.h" /// class header file // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC FUNCTIONS /* * only change the word member var if it is in its initial state */ void Entry::setWordPtr(char *w_ptr) { if(m_word_ptr == NULL) { m_word_ptr = w_ptr; } } /* * only change the def member var if it is in its initial state */ void Entry::setDefPtr(char *d_ptr) { if(m_def_ptr == NULL) { m_word_ptr = d_ptr; } }

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Sun Fire X4800 M2 Delivers World Record TPC-C for x86 Systems

- by Brian

Oracle's Sun Fire X4800 M2 server equipped with eight 2.4 GHz Intel Xeon Processor E7-8870 chips obtained a result of 5,055,888 tpmC on the TPC-C benchmark. This result is a world record for x86 servers. Oracle demonstrated this world record database performance running Oracle Database 11g Release 2 Enterprise Edition with Partitioning. The Sun Fire X4800 M2 server delivered a new x86 TPC-C world record of 5,055,888 tpmC with a price performance of $0.89/tpmC using Oracle Database 11g Release 2. This configuration is available 06/26/12. The Sun Fire X4800 M2 server delivers 3.0x times better performance than the next 8-processor result, an IBM System p 570 equipped with POWER6 processors. The Sun Fire X4800 M2 server has 3.1x times better price/performance than the 8-processor 4.7GHz POWER6 IBM System p 570. The Sun Fire X4800 M2 server has 1.6x times better performance than the 4-processor IBM x3850 X5 system equipped with Intel Xeon processors. This is the first TPC-C result on any system using eight Intel Xeon Processor E7-8800 Series chips. The Sun Fire X4800 M2 server is the first x86 system to get over 5 million tpmC. The Oracle solution utilized Oracle Linux operating system and Oracle Database 11g Enterprise Edition Release 2 with Partitioning to produce the x86 world record TPC-C benchmark performance. Performance Landscape Select TPC-C results (sorted by tpmC, bigger is better) System p/c/t tpmC Price/tpmC Avail Database MemorySize Sun Fire X4800 M2 8/80/160 5,055,888 0.89 USD 6/26/2012 Oracle 11g R2 4 TB IBM x3850 X5 4/40/80 3,014,684 0.59 USD 7/11/2011 DB2 ESE 9.7 3 TB IBM x3850 X5 4/32/64 2,308,099 0.60 USD 5/20/2011 DB2 ESE 9.7 1.5 TB IBM System p 570 8/16/32 1,616,162 3.54 USD 11/21/2007 DB2 9.0 2 TB p/c/t - processors, cores, threads Avail - availability date Oracle and IBM TPC-C Response times System tpmC Response Time (sec) New Order 90th% Response Time (sec) New Order Average Sun Fire X4800 M2 5,055,888 0.210 0.166 IBM x3850 X5 3,014,684 0.500 0.272 Ratios - Oracle Better 1.6x 1.4x 1.3x Oracle uses average new order response time for comparison between Oracle and IBM. Graphs of Oracle's and IBM's response times for New-Order can be found in the full disclosure reports on TPC's website TPC-C Official Result Page. Configuration Summary and Results Hardware Configuration: Server Sun Fire X4800 M2 server 8 x 2.4 GHz Intel Xeon Processor E7-8870 4 TB memory 8 x 300 GB 10K RPM SAS internal disks 8 x Dual port 8 Gbs FC HBA Data Storage 10 x Sun Fire X4270 M2 servers configured as COMSTAR heads, each with 1 x 3.06 GHz Intel Xeon X5675 processor 8 GB memory 10 x 2 TB 7.2K RPM 3.5" SAS disks 2 x Sun Storage F5100 Flash Array storage (1.92 TB each) 1 x Brocade 5300 switches Redo Storage 2 x Sun Fire X4270 M2 servers configured as COMSTAR heads, each with 1 x 3.06 GHz Intel Xeon X5675 processor 8 GB memory 11 x 2 TB 7.2K RPM 3.5" SAS disks Clients 8 x Sun Fire X4170 M2 servers, each with 2 x 3.06 GHz Intel Xeon X5675 processors 48 GB memory 2 x 300 GB 10K RPM SAS disks Software Configuration: Oracle Linux (Sun Fire 4800 M2) Oracle Solaris 11 Express (COMSTAR for Sun Fire X4270 M2) Oracle Solaris 10 9/10 (Sun Fire X4170 M2) Oracle Database 11g Release 2 Enterprise Edition with Partitioning Oracle iPlanet Web Server 7.0 U5 Tuxedo CFS-R Tier 1 Results: System: Sun Fire X4800 M2 tpmC: 5,055,888 Price/tpmC: 0.89 USD Available: 6/26/2012 Database: Oracle Database 11g Cluster: no New Order Average Response: 0.166 seconds Benchmark Description TPC-C is an OLTP system benchmark. It simulates a complete environment where a population of terminal operators executes transactions against a database. The benchmark is centered around the principal activities (transactions) of an order-entry environment. These transactions include entering and delivering orders, recording payments, checking the status of orders, and monitoring the level of stock at the warehouses. Key Points and Best Practices Oracle Database 11g Release 2 Enterprise Edition with Partitioning scales easily to this high level of performance. COMSTAR (Common Multiprotocol SCSI Target) is the software framework that enables an Oracle Solaris host to serve as a SCSI Target platform. COMSTAR uses a modular approach to break the huge task of handling all the different pieces in a SCSI target subsystem into independent functional modules which are glued together by the SCSI Target Mode Framework (STMF). The modules implementing functionality at SCSI level (disk, tape, medium changer etc.) are not required to know about the underlying transport. And the modules implementing the transport protocol (FC, iSCSI, etc.) are not aware of the SCSI-level functionality of the packets they are transporting. The framework hides the details of allocation providing execution context and cleanup of SCSI commands and associated resources and simplifies the task of writing the SCSI or transport modules. Oracle iPlanet Web Server middleware is used for the client tier of the benchmark. Each web server instance supports more than a quarter-million users while satisfying the response time requirement from the TPC-C benchmark. See Also Oracle Press Release -- Sun Fire X4800 M2 TPC-C Executive Summary tpc.org Complete Sun Fire X4800 M2 TPC-C Full Disclosure Report tpc.org Transaction Processing Performance Council (TPC) Home Page Ideas International Benchmark Page Sun Fire X4800 M2 Server oracle.com OTN Oracle Linux oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Sun Storage F5100 Flash Array oracle.com OTN Disclosure Statement TPC Benchmark C, tpmC, and TPC-C are trademarks of the Transaction Processing Performance Council (TPC). Sun Fire X4800 M2 (8/80/160) with Oracle Database 11g Release 2 Enterprise Edition with Partitioning, 5,055,888 tpmC, $0.89 USD/tpmC, available 6/26/2012. IBM x3850 X5 (4/40/80) with DB2 ESE 9.7, 3,014,684 tpmC, $0.59 USD/tpmC, available 7/11/2011. IBM x3850 X5 (4/32/64) with DB2 ESE 9.7, 2,308,099 tpmC, $0.60 USD/tpmC, available 5/20/2011. IBM System p 570 (8/16/32) with DB2 9.0, 1,616,162 tpmC, $3.54 USD/tpmC, available 11/21/2007. Source: http://www.tpc.org/tpcc, results as of 7/15/2011.

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ASP.NET Web API - Screencast series Part 4: Paging and Querying

- by Jon Galloway

We're continuing a six part series on ASP.NET Web API that accompanies the getting started screencast series. This is an introductory screencast series that walks through from File / New Project to some more advanced scenarios like Custom Validation and Authorization. The screencast videos are all short (3-5 minutes) and the sample code for the series is both available for download and browsable online. I did the screencasts, but the samples were written by the ASP.NET Web API team. In Part 1 we looked at what ASP.NET Web API is, why you'd care, did the File / New Project thing, and did some basic HTTP testing using browser F12 developer tools. In Part 2 we started to build up a sample that returns data from a repository in JSON format via GET methods. In Part 3, we modified data on the server using DELETE and POST methods. In Part 4, we'll extend on our simple querying methods form Part 2, adding in support for paging and querying. This part shows two approaches to querying data (paging really just being a specific querying case) - you can do it yourself using parameters passed in via querystring (as well as headers, other route parameters, cookies, etc.). You're welcome to do that if you'd like. What I think is more interesting here is that Web API actions that return IQueryable automatically support OData query syntax, making it really easy to support some common query use cases like paging and filtering. A few important things to note: This is just support for OData query syntax - you're not getting back data in OData format. The screencast demonstrates this by showing the GET methods are continuing to return the same JSON they did previously. So you don't have to "buy in" to the whole OData thing, you're just able to use the query syntax if you'd like. This isn't full OData query support - full OData query syntax includes a lot of operations and features - but it is a pretty good subset: filter, orderby, skip, and top. All you have to do to enable this OData query syntax is return an IQueryable rather than an IEnumerable. Often, that could be as simple as using the AsQueryable() extension method on your IEnumerable. Query composition support lets you layer queries intelligently. If, for instance, you had an action that showed products by category using a query in your repository, you could also support paging on top of that. The result is an expression tree that's evaluated on-demand and includes both the Web API query and the underlying query. So with all those bullet points and big words, you'd think this would be hard to hook up. Nope, all I did was change the return type from IEnumerable<Comment> to IQueryable<Comment> and convert the Get() method's IEnumerable result using the .AsQueryable() extension method. public IQueryable<Comment> GetComments() { return repository.Get().AsQueryable(); } You still need to build up the query to provide the $top and $skip on the client, but you'd need to do that regardless. Here's how that looks: $(function () { //--------------------------------------------------------- // Using Queryable to page //--------------------------------------------------------- $("#getCommentsQueryable").click(function () { viewModel.comments([]); var pageSize = $('#pageSize').val(); var pageIndex = $('#pageIndex').val(); var url = "/api/comments?$top=" + pageSize + '&$skip=' + (pageIndex * pageSize); $.getJSON(url, function (data) { // Update the Knockout model (and thus the UI) with the comments received back // from the Web API call. viewModel.comments(data); }); return false; }); }); And the neat thing is that - without any modification to our server-side code - we can modify the above jQuery call to request the comments be sorted by author: $(function () { //--------------------------------------------------------- // Using Queryable to page //--------------------------------------------------------- $("#getCommentsQueryable").click(function () { viewModel.comments([]); var pageSize = $('#pageSize').val(); var pageIndex = $('#pageIndex').val(); var url = "/api/comments?$top=" + pageSize + '&$skip=' + (pageIndex * pageSize) + '&$orderby=Author'; $.getJSON(url, function (data) { // Update the Knockout model (and thus the UI) with the comments received back // from the Web API call. viewModel.comments(data); }); return false; }); }); So if you want to make use of OData query syntax, you can. If you don't like it, you're free to hook up your filtering and paging however you think is best. Neat. In Part 5, we'll add on support for Data Annotation based validation using an Action Filter.

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Find only physical network adapters with WMI Win32_NetworkAdapter class

- by Mladen Prajdic

WMI is Windows Management Instrumentation infrastructure for managing data and machines. We can access it by using WQL (WMI querying language or SQL for WMI). One thing to remember from the WQL link is that it doesn't support ORDER BY. This means that when you do SELECT * FROM wmiObject, the returned order of the objects is not guaranteed. It can return adapters in different order based on logged-in user, permissions of that user, etc… This is not documented anywhere that I've looked and is derived just from my observations. To get network adapters we have to query the Win32_NetworkAdapter class. This returns us all network adapters that windows detect, real and virtual ones, however it only supplies IPv4 data. I've tried various methods of combining properties that are common on all systems since Windows XP. The first thing to do to remove all virtual adapters (like tunneling, WAN miniports, etc…) created by Microsoft. We do this by adding WHERE Manufacturer!='Microsoft' to our WMI query. This greatly narrows the number of adapters we have to work with. Just on my machine it went from 20 adapters to 5. What was left were one real physical Realtek LAN adapter, 2 virtual adapters installed by VMware and 2 virtual adapters installed by VirtualBox. If you read the Win32_NetworkAdapter help page you'd notice that there's an AdapterType that enumerates various adapter types like LAN or Wireless and AdapterTypeID that gives you the same information as AdapterType only in integer form. The dirty little secret is that these 2 properties don't work. They are both hardcoded, AdapterTypeID to "0" and AdapterType to "Ethernet 802.3". The only exceptions I've seen so far are adapters that have no values at all for the two properties, "RAS Async Adapter" that has values of AdapterType = "Wide Area Network" and AdapterTypeID = "3" and various tunneling adapters that have values of AdapterType = "Tunnel" and AdapterTypeID = "15". In the help docs there isn't even a value for 15. So this property was of no help. Next property to give hope is NetConnectionId. This is the name of the network connection as it appears in the Control Panel -> Network Connections. Problem is this value is also localized into various languages and can have different names for different connection. So both of these properties don't help and we haven't even started talking about eliminating virtual adapters. Same as the previous one this property was also of no help. Next two properties I checked were ConfigManagerErrorCode and NetConnectionStatus in hopes of finding disabled and disconnected adapters. If an adapter is enabled but disconnected the ConfigManagerErrorCode = 0 with different NetConnectionStatus. If the adapter is disabled it reports ConfigManagerErrorCode = 22. This looked like a win by using (ConfigManagerErrorCode=0 or ConfigManagerErrorCode=22) in our condition. This way we get enabled (connected and disconnected adapters). Problem with all of the above properties is that none of them filter out the virtual adapters installed by virtualization software like VMware and VirtualBox. The last property to give hope is PNPDeviceID. There's an interesting observation about physical and virtual adapters with this property. Every virtual adapter PNPDeviceID starts with "ROOT\". Even VMware and VirtualBox ones. There were some really, really old physical adapters that had PNPDeviceID starting with "ROOT\" but those were in pre win XP era AFAIK. Since my minimum system to check was Windows XP SP2 I didn't have to worry about those. The only virtual adapter I've seen to not have PNPDeviceID start with "ROOT\" is the RAS Async Adapter for Wide Area Network. But because it is made by Microsoft we've eliminated it with the first condition for the manufacturer. Using the PNPDeviceID has so far proven to be really effective and I've tested it on over 20 different computers of various configurations from Windows XP laptops with wireless and bluetooth cards to virtualized Windows 2008 R2 servers. So far it always worked as expected. I will appreciate you letting me know if you find a configuration where it doesn't work. Let's see some C# code how to do this: ManagementObjectSearcher mos = null;// WHERE Manufacturer!='Microsoft' removes all of the // Microsoft provided virtual adapters like tunneling, miniports, and Wide Area Network adapters.mos = new ManagementObjectSearcher(@"SELECT * FROM Win32_NetworkAdapter WHERE Manufacturer != 'Microsoft'");// Trying the ConfigManagerErrorCode and NetConnectionStatus variations // proved to still not be enough and it returns adapters installed by // the virtualization software like VMWare and VirtualBox// ConfigManagerErrorCode = 0 -> Device is working properly. This covers enabled and/or disconnected devices// ConfigManagerErrorCode = 22 AND NetConnectionStatus = 0 -> Device is disabled and Disconnected. // Some virtual devices report ConfigManagerErrorCode = 22 (disabled) and some other NetConnectionStatus than 0mos = new ManagementObjectSearcher(@"SELECT * FROM Win32_NetworkAdapter WHERE Manufacturer != 'Microsoft' AND (ConfigManagerErrorCode = 0 OR (ConfigManagerErrorCode = 22 AND NetConnectionStatus = 0))");// Final solution with filtering on the Manufacturer and PNPDeviceID not starting with "ROOT\"// Physical devices have PNPDeviceID starting with "PCI\" or something else besides "ROOT\"mos = new ManagementObjectSearcher(@"SELECT * FROM Win32_NetworkAdapter WHERE Manufacturer != 'Microsoft' AND NOT PNPDeviceID LIKE 'ROOT\\%'");// Get the physical adapters and sort them by their index. // This is needed because they're not sorted by defaultIList<ManagementObject> managementObjectList = mos.Get() .Cast<ManagementObject>() .OrderBy(p => Convert.ToUInt32(p.Properties["Index"].Value)) .ToList();// Let's just show all the properties for all physical adapters.foreach (ManagementObject mo in managementObjectList){ foreach (PropertyData pd in mo.Properties) Console.WriteLine(pd.Name + ": " + (pd.Value ?? "N/A"));} That's it. Hope this helps you in some way.

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JQuery and the multiple date selector

- by David Carter

Overview I recently needed to build a web page that would allow a user to capture some information and most importantly select multiple dates. This functionality was core to the application and hence had to be easy and quick to do. This is a public facing website so it had to be intuitive and very responsive. On the face of it it didn't seem too hard, I know enough juery to know what it is capable of and I was pretty sure that there would be some plugins that would help speed things along the way. I'm using ASP.Net MVC for this project as I really like the control that it gives you over the generated html and javascript. After years of Web Forms development it makes me feel like a web developer again and puts a smile on my face, that can only be a good thing! The Calendar The first item that I needed on this page was a calender and I wanted the ability to: have the calendar be always visible select/deselect multiple dates at the same time bind to the select/deselect event so that I could update a seperate listing of the selected dates allow the user to move to another month and still have the calender remember any dates in the previous month I was hoping that there was a jQuery plugin that would meet my requirements and luckily there was! The jQuery datepicker does everything I want and there is quite a bit of documentation on how to use it. It makes use of a javascript date library date.js which I had not come across before but has a number of very useful date utilities that I have used elsewhere in the project. As you can see from the image there still needs to be some styling done! But there will be plenty of time for that later. The calendar clearly shows which dates the user has selected in red and i also make use of an unordered list to show the the selected dates so the user can always clearly see what has been selected even if they move to another month on the calendar. The javascript code that is responsible for listening to events on the calendar and synchronising the list look as follows: <script type="text/javascript"> $(function () { $('.datepicker').datePicker({ inline: true, selectMultiple: true }) .bind( 'dateSelected', function (e, selectedDate, $td, state) { var dateInMillisecs = selectedDate.valueOf(); if (state) { //adding a date var newDate = new Date(selectedDate); //insert the new item into the correct place in the list var listitems = $('#dateList').children('li').get(); var liToAdd = "<li id='" + dateInMillisecs + "' >" + newDate.toString('ddd dd MMM yyyy') + "</li>"; var targetIndex = -1; for (var i = 0; i < listitems.length; i++) { if (dateInMillisecs <= listitems[i].id) { targetIndex = i; break; } } if (targetIndex < 0) { $('#dateList').append(liToAdd); } else { $($('#dateList').children("li")[targetIndex]).before(liToAdd); } } else {//removing a date $('ul #' + dateInMillisecs).remove(); } } ) }); When a date is selected on the calendar a function is called with a number of parameters passed to it. The ones I am particularly interested in are selectedDate and state. State tells me whether the user has selected or deselected the date passed in the selectedDate parameter. The <ul> that I am using to show the date has an id of dateList and this is what I will be adding and removing <li> items from. To make things a little more logical for the user I decided that the date should be sorted in chronological order, this means that each time a new date is selected it need to be placed in the correct position in the list. One way to do this would be just to append a new <li> to the list and then sort the whole list. However the approach I took was to get an array of all the items in the list var listitems = ('#dateList').children('li').get(); and then check the value of each item in the array against my new date and as soon as I found the case where the new date was less than the current item remember that position in the list as this is where I would insert it later. To make this work easily I decided to store a numeric representation of each date in the list in the id attribute of each <li> element. Fortunately javascript natively stores dates as the number of milliseconds since 1 Jan 1970. var dateInMillisecs = selectedDate.valueOf(); Please note that this is the value of the date in UTC! I always like to store dates in UTC as I learnt a long time ago that it saves a lot of refactoring at a later date... When I convert the dates back to their original back on the server I will need the UTC offset that was used when calculating the dates, this and how to actually serialise the dates and get them posted back will be the subject of another post.

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SQL SERVER – Weekly Series – Memory Lane – #053 – Final Post in Series

- by Pinal Dave

It has been a fantastic journey to write memory lane series for an entire year. This series gave me the opportunity to go back and see what I have contributed to this blog throughout the last 7 years. This was indeed fantastic series as this provided me the opportunity to witness how technology has grown throughout the year and how I have progressed in my career while writing this blog post. This series was indeed fantastic experience readers as many joined during the last few years and were not sure what they have missed in recent years. Let us continue with the final episode of the Memory Lane Series. Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Get Current User – Get Logged In User Here is the straight script which list logged in SQL Server users. Disable All Triggers on a Database – Disable All Triggers on All Servers Question : How to disable all the triggers for a database? Additionally, how to disable all the triggers for all servers? For answer execute the script in the blog post. Importance of Master Database for SQL Server Startup I have received following questions many times. I will list all the questions here and answer them together. What is the purpose of Master database? Should our backup Master database? Which database is must have database for SQL Server for startup? Which are the default system database created when SQL Server 2005 is installed for the first time? What happens if Master database is corrupted? Answers to all of the questions are very much related. 2008 DECLARE Multiple Variables in One Statement SQL Server is a great product and it has many features which are very unique to SQL Server. Regarding feature of SQL Server where multiple variable can be declared in one statement, it is absolutely possible to do. 2009 How to Enable Index – How to Disable Index – Incorrect syntax near ‘ENABLE’ Many times I have seen that the index is disabled when there is a large update operation on the table. Bulk insert of very large file updates in any table using SSIS is usually preceded by disabling the index and followed by enabling the index. I have seen many developers running the following query to disable the index. 2010 List of all the Views from Database Many emails I received suggesting that they have hundreds of the view and now have no clue what is going on and how many of them have indexes and how many does not have an index. Some even asked me if there is any way they can get a list of the views with the property of Index along with it. Here is the quick script which does exactly the same. You can also include many other columns from the same view. Minimum Maximum Memory – Server Memory Options I was recently reading about SQL Server Memory Options over here. While reading this one line really caught my attention is minimum value allowed for maximum memory options. The default setting for min server memory is 0, and the default setting for max server memory is 2147483647. The minimum amount of memory you can specify for max server memory is 16 megabytes (MB). 2011 Fundamentals of Columnstore Index There are two kinds of storage in a database. Row Store and Column Store. Row store does exactly as the name suggests – stores rows of data on a page – and column store stores all the data in a column on the same page. These columns are much easier to search – instead of a query searching all the data in an entire row whether the data are relevant or not, column store queries need only to search a much lesser number of the columns. How to Ignore Columnstore Index Usage in Query In summary the question in simple words “How can we ignore using the column store index in selective queries?” Very interesting question – you can use I can understand there may be the cases when the column store index is not ideal and needs to be ignored the same. You can use the query hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX to ignore the column store index. The SQL Server Engine will use any other index which is best after ignoring the column store index. 2012 Storing Variable Values in Temporary Array or Temporary List SQL Server does not support arrays or a dynamic length storage mechanism like list. Absolutely there are some clever workarounds and few extra-ordinary solutions but everybody can;t come up with such solution. Additionally, sometime the requirements are very simple that doing extraordinary coding is not required. Here is the simple case. Move Database Files MDF and LDF to Another Location It is not common to keep the Database on the same location where OS is installed. Usually Database files are in SAN, Separate Disk Array or on SSDs. This is done usually for performance reason and manageability perspective. Now the challenges comes up when database which was installed at not preferred default location and needs to move to a different location. Here is the quick tutorial how you can do it. UNION ALL and ORDER BY – How to Order Table Separately While Using UNION ALL If your requirement is such that you want your top and bottom query of the UNION resultset independently sorted but in the same result set you can add an additional static column and order by that column. Let us re-create the same scenario. Copy Data from One Table to Another Table – SQL in Sixty Seconds #031 – Video http://www.youtube.com/watch?v=FVWIA-ACMNo Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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Sort Data in Windows Phone using Collection View Source

- by psheriff

When you write a Windows Phone application you will most likely consume data from a web service somewhere. If that service returns data to you in a sort order that you do not want, you have an easy alternative to sort the data without writing any C# or VB code. You use the built-in CollectionViewSource object in XAML to perform the sorting for you. This assumes that you can get the data into a collection that implements the IEnumerable or IList interfaces.For this example, I will be using a simple Product class with two properties, and a list of Product objects using the Generic List class. Try this out by creating a Product class as shown in the following code:public class Product { public Product(int id, string name) { ProductId = id; ProductName = name; } public int ProductId { get; set; } public string ProductName { get; set; }}Create a collection class that initializes a property called DataCollection with some sample data as shown in the code below:public class Products : List<Product>{ public Products() { InitCollection(); } public List<Product> DataCollection { get; set; } List<Product> InitCollection() { DataCollection = new List<Product>(); DataCollection.Add(new Product(3, "PDSA .NET Productivity Framework")); DataCollection.Add(new Product(1, "Haystack Code Generator for .NET")); DataCollection.Add(new Product(2, "Fundamentals of .NET eBook")); return DataCollection; }}Notice that the data added to the collection is not in any particular order. Create a Windows Phone page and add two XML namespaces to the Page.xmlns:scm="clr-namespace:System.ComponentModel;assembly=System.Windows"xmlns:local="clr-namespace:WPSortData"The 'local' namespace is an alias to the name of the project that you created (in this case WPSortData). The 'scm' namespace references the System.Windows.dll and is needed for the SortDescription class that you will use for sorting the data. Create a phone:PhoneApplicationPage.Resources section in your Windows Phone page that looks like the following:<phone:PhoneApplicationPage.Resources> <local:Products x:Key="products" /> <CollectionViewSource x:Key="prodCollection" Source="{Binding Source={StaticResource products}, Path=DataCollection}"> <CollectionViewSource.SortDescriptions> <scm:SortDescription PropertyName="ProductName" Direction="Ascending" /> </CollectionViewSource.SortDescriptions> </CollectionViewSource></phone:PhoneApplicationPage.Resources>The first line of code in the resources section creates an instance of your Products class. The constructor of the Products class calls the InitCollection method which creates three Product objects and adds them to the DataCollection property of the Products class. Once the Products object is instantiated you now add a CollectionViewSource object in XAML using the Products object as the source of the data to this collection. A CollectionViewSource has a SortDescriptions collection that allows you to specify a set of SortDescription objects. Each object can set a PropertyName and a Direction property. As you see in the above code you set the PropertyName equal to the ProductName property of the Product object and tell it to sort in an Ascending direction.All you have to do now is to create a ListBox control and set its ItemsSource property to the CollectionViewSource object. The ListBox displays the data in sorted order by ProductName and you did not have to write any LINQ queries or write other code to sort the data!<ListBox ItemsSource="{Binding Source={StaticResource prodCollection}}" DisplayMemberPath="ProductName" />SummaryIn this blog post you learned that you can sort any data without having to change the source code of where the data comes from. Simply feed the data into a CollectionViewSource in XAML and set some sort descriptions in XAML and the rest is done for you! This comes in very handy when you are consuming data from a source where the data is given to you and you do not have control over the sorting.NOTE: You can download this article and many samples like the one shown in this blog entry at my website. http://www.pdsa.com/downloads. Select “Tips and Tricks”, then “Sort Data in Windows Phone using Collection View Source” from the drop down list.Good Luck with your Coding,Paul Sheriff** SPECIAL OFFER FOR MY BLOG READERS **We frequently offer a FREE gift for readers of my blog. Visit http://www.pdsa.com/Event/Blog for your FREE gift!

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Using Windows Previous Versions to access ZFS Snapshots (July 14, 2009)

- by user12612012

The Previous Versions tab on the Windows desktop provides a straightforward, intuitive way for users to view or recover files from ZFS snapshots. ZFS snapshots are read-only, point-in-time instances of a ZFS dataset, based on the same copy-on-write transactional model used throughout ZFS. ZFS snapshots can be used to recover deleted files or previous versions of files and they are space efficient because unchanged data is shared between the file system and its snapshots. Snapshots are available locally via the .zfs/snapshot directory and remotely via Previous Versions on the Windows desktop. Shadow Copies for Shared Folders was introduced with Windows Server 2003 but subsequently renamed to Previous Versions with the release of Windows Vista and Windows Server 2008. Windows shadow copies, or snapshots, are based on the Volume Snapshot Service (VSS) and, as the [Shared Folders part of the] name implies, are accessible to clients via SMB shares, which is good news when using the Solaris CIFS Service. And the nice thing is that no additional configuration is required - it "just works". On Windows clients, snapshots are accessible via the Previous Versions tab in Windows Explorer using the Shadow Copy client, which is available by default on Windows XP SP2 and later. For Windows 2000 and pre-SP2 Windows XP, the client software is available for download from Microsoft: Shadow Copies for Shared Folders Client. Assuming that we already have a shared ZFS dataset, we can create ZFS snapshots and view them from a Windows client. zfs snapshot tank/home/administrator@snap101zfs snapshot tank/home/administrator@snap102 To view the snapshots on Windows, map the dataset on the client then right click on a folder or file and select Previous Versions. Note that Windows will only display previous versions of objects that differ from the originals. So you may have to modify files after creating a snapshot in order to see previous versions of those files. The screenshot above shows various snapshots in the Previous Versions window, created at different times. On the left panel, the .zfs folder is visible, illustrating that this is a ZFS share. The .zfs setting can be toggled as desired, it makes no difference when using previous versions. To make the .zfs folder visible: zfs set snapdir=visible tank/home/administrator To hide the .zfs folder: zfs set snapdir=hidden tank/home/administrator The following screenshot shows the Previous Versions panel when a file has been selected. In this case the user is prompted to view, copy or restore the file from one of the available snapshots. As can be seen from the screenshots above, the Previous Versions window doesn't display snapshot names: snapshots are listed by snapshot creation time, sorted in time order from most recent to oldest. There's nothing we can do about this, it's the way that the interface works. Perhaps one point of note, to avoid confusion, is that the ZFS snapshot creation time isnot the same as the root directory creation timestamp. In ZFS, all object attributes in the original dataset are preserved when a snapshot is taken, including the creation time of the root directory. Thus the root directory creation timestamp is the time that the directory was created in the original dataset. # ls -d% all /home/administrator timestamp: atime Mar 19 15:40:23 2009 timestamp: ctime Mar 19 15:40:58 2009 timestamp: mtime Mar 19 15:40:58 2009 timestamp: crtime Mar 19 15:18:34 2009 # ls -d% all /home/administrator/.zfs/snapshot/snap101 timestamp: atime Mar 19 15:40:23 2009 timestamp: ctime Mar 19 15:40:58 2009 timestamp: mtime Mar 19 15:40:58 2009 timestamp: crtime Mar 19 15:18:34 2009 The snapshot creation time can be obtained using the zfs command as shown below. # zfs get all tank/home/administrator@snap101NAME PROPERTY VALUEtank/home/administrator@snap101 type snapshottank/home/administrator@snap101 creation Mon Mar 23 18:21 2009 In this example, the dataset was created on March 19th and the snapshot was created on March 23rd. In conclusion, Shadow Copies for Shared Folders provides a straightforward way for users to view or recover files from ZFS snapshots. The Windows desktop provides an easy to use, intuitive GUI and no configuration is required to use or access previous versions of files or folders. REFERENCES FOR MORE INFORMATION ZFS ZFS Learning Center Introduction to Shadow Copies of Shared Folders Shadow Copies for Shared Folders Client

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SQL SERVER – ?Finding Out What Changed in a Deleted Database – Notes from the Field #041

- by Pinal Dave

[Note from Pinal]: This is a 41th episode of Notes from the Field series. The real world is full of challenges. When we are reading theory or book, we sometimes do not realize how real world reacts works and that is why we have the series notes from the field, which is extremely popular with developers and DBA. Let us talk about interesting problem of how to figure out what has changed in the DELETED database. Well, you think I am just throwing the words but in reality this kind of problems are making our DBA’s life interesting and in this blog post we have amazing story from Brian Kelley about the same subject. In this episode of the Notes from the Field series database expert Brian Kelley explains a how to find out what has changed in deleted database. Read the experience of Brian in his own words. Sometimes, one of the hardest questions to answer is, “What changed?” A similar question is, “Did anything change other than what we expected to change?” The First Place to Check – Schema Changes History Report: Pinal has recently written on the Schema Changes History report and its requirement for the Default Trace to be enabled. This is always the first place I look when I am trying to answer these questions. There are a couple of obvious limitations with the Schema Changes History report. First, while it reports what changed, when it changed, and who changed it, other than the base DDL operation (CREATE, ALTER, DELETE), it does not present what the changes actually were. This is not something covered by the default trace. Second, the default trace has a fixed size. When it hits that size, the changes begin to overwrite. As a result, if you wait too long, especially on a busy database server, you may find your changes rolled off. But the Database Has Been Deleted! Pinal cited another issue, and that’s the inability to run the Schema Changes History report if the database has been dropped. Thankfully, all is not lost. One thing to remember is that the Schema Changes History report is ultimately driven by the Default Trace. As you may have guess, it’s a trace, like any other database trace. And the Default Trace does write to disk. The trace files are written to the defined LOG directory for that SQL Server instance and have a prefix of log_: Therefore, you can read the trace files like any other. Tip: Copy the files to a working directory. Otherwise, you may occasionally receive a file in use error. With the Default Trace files, if you ask the question early enough, you can see the information for a deleted database just the same as any other database. Testing with a Deleted Database: Here’s a short script that will create a database, create a schema, create an object, and then drop the database. Without the database, you can’t do a standard Schema Changes History report. CREATE DATABASE DeleteMe; GO USE DeleteMe; GO CREATE SCHEMA Test AUTHORIZATION dbo; GO CREATE TABLE Test.Foo (FooID INT); GO USE MASTER; GO DROP DATABASE DeleteMe; GO This sets up the perfect situation where we can’t retrieve the information using the Schema Changes History report but where it’s still available. Finding the Information: I’ve sorted the columns so I can see the Event Subclass, the Start Time, the Database Name, the Object Name, and the Object Type at the front, but otherwise, I’m just looking at the trace files using SQL Profiler. As you can see, the information is definitely there: Therefore, even in the case of a dropped/deleted database, you can still determine who did what and when. You can even determine who dropped the database (loginame is captured). The key is to get the default trace files in a timely manner in order to extract the information. If you want to get started with performance tuning and database security with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, T SQL

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spliiting code in java-don't know what's wrong [closed]

- by ???? ?????

I'm writing a code to split a file into many files with a size specified in the code, and then it will join these parts later. The problem is with the joining code, it doesn't work and I can't figure what is wrong! This is my code: import java.io.*; import java.util.*; public class StupidSplit { static final int Chunk_Size = 10; static int size =0; public static void main(String[] args) throws IOException { String file = "b.txt"; int chunks = DivideFile(file); System.out.print((new File(file)).delete()); System.out.print(JoinFile(file, chunks)); } static boolean JoinFile(String fname, int nChunks) { /* * Joins the chunks together. Chunks have been divided using DivideFile * function so the last part of filename will ".partxxxx" Checks if all * parts are together by matching number of chunks found against * "nChunks", then joins the file otherwise throws an error. */ boolean successful = false; File currentDirectory = new File(System.getProperty("user.dir")); // File[] fileList = currentDirectory.listFiles(); /* populate only the files having extension like "partxxxx" */ List<File> lst = new ArrayList<File>(); // Arrays.sort(fileList); for (File file : fileList) { if (file.isFile()) { String fnm = file.getName(); int lastDot = fnm.lastIndexOf('.'); // add to list which match the name given by "fname" and have //"partxxxx" as extension" if (fnm.substring(0, lastDot).equalsIgnoreCase(fname) && (fnm.substring(lastDot + 1)).substring(0, 4).equals("part")) { lst.add(file); } } } /* * sort the list - it will be sorted by extension only because we have * ensured that list only contains those files that have "fname" and * "part" */ File[] files = (File[]) lst.toArray(new File[0]); Arrays.sort(files); System.out.println("size ="+files.length); System.out.println("hello"); /* Ensure that number of chunks match the length of array */ if (files.length == nChunks-1) { File ofile = new File(fname); FileOutputStream fos; FileInputStream fis; byte[] fileBytes; int bytesRead = 0; try { fos = new FileOutputStream(ofile,true); for (File file : files) { fis = new FileInputStream(file); fileBytes = new byte[(int) file.length()]; bytesRead = fis.read(fileBytes, 0, (int) file.length()); assert(bytesRead == fileBytes.length); assert(bytesRead == (int) file.length()); fos.write(fileBytes); fos.flush(); fileBytes = null; fis.close(); fis = null; } fos.close(); fos = null; } catch (FileNotFoundException fnfe) { System.out.println("Could not find file"); successful = false; return successful; } catch (IOException ioe) { System.out.println("Cannot write to disk"); successful = false; return successful; } /* ensure size of file matches the size given by server */ successful = (ofile.length() == StupidSplit.size) ? true : false; } else { successful = false; } return successful; } static int DivideFile(String fname) { File ifile = new File(fname); FileInputStream fis; String newName; FileOutputStream chunk; //int fileSize = (int) ifile.length(); double fileSize = (double) ifile.length(); //int nChunks = 0, read = 0, readLength = Chunk_Size; int nChunks = 0, read = 0, readLength = Chunk_Size; byte[] byteChunk; try { fis = new FileInputStream(ifile); StupidSplit.size = (int)ifile.length(); while (fileSize > 0) { if (fileSize <= Chunk_Size) { readLength = (int) fileSize; } byteChunk = new byte[readLength]; read = fis.read(byteChunk, 0, readLength); fileSize -= read; assert(read==byteChunk.length); nChunks++; //newName = fname + ".part" + Integer.toString(nChunks - 1); newName = String.format("%s.part%09d", fname, nChunks - 1); chunk = new FileOutputStream(new File(newName)); chunk.write(byteChunk); chunk.flush(); chunk.close(); byteChunk = null; chunk = null; } fis.close(); System.out.println(nChunks); // fis = null; } catch (FileNotFoundException fnfe) { System.out.println("Could not find the given file"); System.exit(-1); } catch (IOException ioe) { System.out .println("Error while creating file chunks. Exiting program"); System.exit(-1); }System.out.println(nChunks); return nChunks; } } }

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Sorting Android ListView

- by aeoth

I'm only starting with Android dev, and while the Milestone is a nice device Java is not my natural language and I'm struggling with both the Google docs on Android SDK, Eclipse and Java itself. Anyway... I'm writing a microblog client for Android to go along with my Windows client (MahTweets). At the moment I've got Tweets coming and going without fail, the problem is with the UI. The initial call will order items correctly (as in highest to lowest) 3 2 1 When a refresh is made 3 2 1 6 5 4 After the tweets are processed, I'm calling adapter.notifyDataSetChanged(); Initially I thought that getItem() on the Adapter needed to be sorted (and the code below is what I ended up with), but I'm still not having any luck. public class TweetAdapter extends BaseAdapter { private List<IStatusUpdate> elements; private Context c; public TweetAdapter(Context c, List<IStatusUpdate> Tweets) { this.elements = Tweets; this.c = c; } public int getCount() { return elements.size(); } public Object getItem(int position) { Collections.sort(elements, new IStatusUpdateComparator()); return elements.get(position); } public long getItemId(int id) { return id; } public void Remove(int id) { notifyDataSetChanged(); } public View getView(int position, View convertView, ViewGroup parent) { RelativeLayout rowLayout; IStatusUpdate t = elements.get(position); rowLayout = t.GetParent().GetUI(t, parent, c); return rowLayout; } class IStatusUpdateComparator implements Comparator { public int compare(Object obj1, Object obj2) { IStatusUpdate update1 = (IStatusUpdate)obj1; IStatusUpdate update2 = (IStatusUpdate)obj2; int result = update1.getID().compareTo(update2.getID()); if (result == -1) return 1; else if (result == 1) return 0; return result; } } } Is there a better way to go about sorting ListViews in Android, while still being able to use the LayoutInflater? (rowLayout = t.GetParent().GetUI(t, parent, c) expands the UI to the specific view which the microblog implementation can provide)

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Sort latitude and longitude coordinates into clockwise ordered quadrilateral

- by Dave Jarvis

Problem Users can provide up to four latitude and longitude coordinates, in any order. They do so with Google Maps. Using Google's Polygon API (v3), the coordinates they select should highlight the selected area between the four coordinates. Solutions and Searches http://www.geocodezip.com/map-markers_ConvexHull_Polygon.asp http://softsurfer.com/Archive/algorithm_0103/algorithm_0103.htm http://stackoverflow.com/questions/2374708/how-to-sort-points-in-a-google-maps-polygon-so-that-lines-do-not-cross http://stackoverflow.com/questions/242404/sort-four-points-in-clockwise-order http://en.literateprograms.org/Quickhull_%28Javascript%29 Graham's scan seems too complicated for four coordinates Sort the coordinates into two arrays (one by latitude, the other longitude) ... then? Jarvis March algorithm? Question How do you sort the coordinates in (counter-)clockwise order, using JavaScript? Code Here is what I have so far: // Ensures the markers are sorted: NW, NE, SE, SW function sortMarkers() { var ns = markers.slice( 0 ); var ew = markers.slice( 0 ); ew.sort( function( a, b ) { if( a.position.lat() < b.position.lat() ) { return -1; } else if( a.position.lat() > b.position.lat() ) { return 1; } return 0; }); ns.sort( function( a, b ) { if( a.position.lng() < b.position.lng() ) { return -1; } else if( a.position.lng() > b.position.lng() ) { return 1; } return 0; }); var nw; var ne; var se; var sw; if( ew.indexOf( ns[0] ) > 1 ) { nw = ns[0]; } else { ne = ns[0]; } if( ew.indexOf( ns[1] ) > 1 ) { nw = ns[1]; } else { ne = ns[1]; } if( ew.indexOf( ns[2] ) > 1 ) { sw = ns[2]; } else { se = ns[2]; } if( ew.indexOf( ns[3] ) > 1 ) { sw = ns[3]; } else { se = ns[3]; } markers[0] = nw; markers[1] = ne; markers[2] = se; markers[3] = sw; } What is a better approach? The recursive Convex Hull algorithm is overkill for four points in the data set. Thank you.

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Finding edge and corner values of an image in matlab

- by James

Hi, this problem links to two other questions i've asked on here. I am tracing the outline of an image and plotting this to a dxf file. I would like to use the bwboundaries function to find the coordinates of the edges of the image, find the corner coordinates using the cornermetric function and then remove any edge coordinates that are not a corner. The important thing I need to be able to do is keep the order of the corner elements obtained from bwboundaries, so that the section traces properly. The dxf function I have that draws from the coordinates draws lines between coordinates that are next to each other, so the line has to be drawn "around" the section rather than straight between the corner points. The reason I am doing this is because there are less coordinates obtained this way, so it is easier to amend the dxf file (as there are less points to manipulate). The code I have so far is: %# Shape to be traced bw = zeros(200); bw(20:40,20:180) = 1; bw(20:180,90:110) = 1; bw(140:180,20:185) = 1; %# Boundary Finding Section [Boundary] = bwboundaries(bw); %Traces the boundary of each section figure, imshow(bw); hold on; colors=['b' 'g' 'r' 'c' 'm' 'y']; for k=1:length(Boundary) perim = Boundary{k}; %Obtains perimeter coordinates (as a 2D matrix) from the cell array cidx = mod(k,length(colors))+1;% Obtains colours for the plot plot(perim(:,2), perim(:,1),... colors(cidx),'LineWidth',2); end Coordmat = cell2mat(Boundary) %Converts the traced regions to a matrix X = Coordmat(:,1) Y = Coordmat(:,2) % This gives the edge coordinates in matrix form %% Corner Finding Section (from Jonas' answer to a previous question %# get corners cornerProbability = cornermetric(bw); cornerIdx = find(cornerProbability==max(cornerProbability(:))); %# Label the image. bwlabel puts 1 for the first feature, 2 for the second, etc. %# Since concave corners are placed just outside the feature, grow the features %# a little before labeling bw2 = imdilate(bw,ones(3)); labeledImage = bwlabel(bw2); %# read the feature number associated with the corner cornerLabels = labeledImage(cornerIdx); %# find all corners that are associated with feature 1 corners_1 = cornerIdx(cornerLabels==1) [Xcorners, Ycorners] = ind2sub(200,corners_1) % Convert subscripts The code I have is, to give a matrix Xfin for the final x coordinates (which are on the edge AND at a corner. Xfin = zeros(length(X),1) for i = Xcorners XFin(i) = Xcorners if i~= Xcorners XFin(i) = [] end end However, this does not work correctly, because the values in the solution are sorted into order, and only one of each value remains. As I said, I would like the corner elements to be in the same order as obtained from bwboundaries, to allow the image to trace properly. Thanks

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Asynchronous callback for network in Objective-C Iphone

- by vodkhang

I am working with network request - response in Objective-C. There is something with asynchronous model that I don't understand. In summary, I have a view that will show my statuses from 2 social networks: Twitter and Facebook. When I clicked refresh, it will call a model manager. That model manager will call 2 service helpers to request for latest items. When 2 service helpers receive data, it will pass back to model manager and this model will add all data into a sorted array. What I don't understand here is that : when response from social networks come back, how many threads will handle the response. From my understanding about multithreading and networking (in Java), there must have 2 threads handle 2 responses and those 2 threads will execute the code to add the responses to the array. So, it can have race condition and the program can go wrong right? Is it the correct working model of iphone objective-C? Or they do it in a different way that it will never have race condition and we don't have to care about locking, synchronize? Here is my example code: ModelManager.m - (void)updateMyItems:(NSArray *)items { self.helpers = [self authenticatedHelpersForAction:NCHelperActionGetMyItems]; for (id<NCHelper> helper in self.helpers) { [helper updateMyItems:items]; // NETWORK request here } } - (void)helper:(id <NCHelper>)helper didReturnItems:(NSArray *)items { [self helperDidFinishGettingMyItems:items callback:@selector(model:didGetMyItems:)]; break; } } // some private attributes int *_currentSocialNetworkItemsCount = 0; // to count the number of items of a social network - (void)helperDidFinishGettingMyItems:(NSArray *)items { for (Item *item in items) { _currentSocialNetworkItemsCount ++; } NSLog(@"count: %d", _currentSocialNetworkItemsCount); _currentSocialNetworkItemsCount = 0; } I want to ask if there is a case that the method helperDidFinishGettingMyItems is called concurrently. That means, for example, faceboook returns 10 items, twitter returns 10 items, will the output of count will ever be larger than 10? And if there is only one single thread, how can the thread finishes parsing 1 response and jump to the other response because, IMO, thread is only executed sequently, block of code by block of code

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