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  • process csv in scala

    - by portoalet
    I am using scala 2.7.7, and wanted to parse CSV file and store the data in SQLite database. I ended up using OpenCSV java library to parse the CSV file, and using sqlitejdbc library. Using these java libraries makes my scala code looks almost identical to that of Java code (sans semicolon and with val/var) As I am dealing with java objects, I can't use scala list, map, etc, unless I do scala2java conversion or upgrade to scala 2.8 Is there a way I can simplify my code further using scala bits that I don't know? val filename = "file.csv"; val reader = new CSVReader(new FileReader(filename)) var aLine = new Array[String](10) var lastSymbol = "" while( (aLine = reader.readNext()) != null ) { if( aLine != null ) { val symbol = aLine(0) if( !symbol.equals(lastSymbol)) { try { val rs = stat.executeQuery("select name from sqlite_master where name='" + symbol + "';" ) if( !rs.next() ) { stat.executeUpdate("drop table if exists '" + symbol + "';") stat.executeUpdate("create table '" + symbol + "' (symbol,data,open,high,low,close,vol);") } } catch { case sqle : java.sql.SQLException => println(sqle) } lastSymbol = symbol } val prep = conn.prepareStatement("insert into '" + symbol + "' values (?,?,?,?,?,?,?);") prep.setString(1, aLine(0)) //symbol prep.setString(2, aLine(1)) //date prep.setString(3, aLine(2)) //open prep.setString(4, aLine(3)) //high prep.setString(5, aLine(4)) //low prep.setString(6, aLine(5)) //close prep.setString(7, aLine(6)) //vol prep.addBatch() prep.executeBatch() } } conn.close()

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  • g++ symbol versioning. Set it to GCC_3.0 using version 4 of g++

    - by Ismael
    Hi all I need to implemente a Java class which uses JNI to control a fiscal printer in XUbuntu 8.10 with sun-java6-jdk installed. The structure is the following: EpsonDriver.java loads libEpson.so libEpson is linked dynamically with EpsonFiscalProtocol.so ( provided by Epson, no source available ) and pthread I use javah to generate the header file, and the code compiles. Then I put the libEpson.so in $JAVA_HOME/jre/lib/i386, and EpsonDriver.java uses an static initializar System.loadLibrary("libEpson") That part works, however, when I try to use any of the methods I get an unsatisfiedLinkError exception. Some time ago, a coworker did a version that works, and using objdump -Dslx I got the following: Program Header: LOAD off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12 filesz 0x0000ccc4 memsz 0x0000ccc4 flags r-x LOAD off 0x0000d000 vaddr 0x0000d000 paddr 0x0000d000 align 2**12 filesz 0x00000250 memsz 0x00044a5c flags rw- DYNAMIC off 0x0000d014 vaddr 0x0000d014 paddr 0x0000d014 align 2**2 filesz 0x000000f0 memsz 0x000000f0 flags rw- NOTE off 0x000000d4 vaddr 0x000000d4 paddr 0x000000d4 align 2**2 filesz 0x00000024 memsz 0x00000024 flags r-- STACK off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2 filesz 0x00000000 memsz 0x00000000 flags rw- Dynamic Section: NEEDED EpsonFiscalProtocol.so NEEDED libpthread.so.0 NEEDED libstdc++.so.6 NEEDED libm.so.6 NEEDED libc.so.6 SONAME libcom_tichile_jpos_EpsonSerialDriver.so INIT 0x00007254 FINI 0x0000ba08 GNU_HASH 0x000000f8 STRTAB 0x00001f50 SYMTAB 0x00000ae0 STRSZ 0x00002384 SYMENT 0x00000010 PLTGOT 0x0000d108 PLTRELSZ 0x00000008 PLTREL 0x00000011 JMPREL 0x0000724c REL 0x000045c4 RELSZ 0x00002c88 RELENT 0x00000008 TEXTREL 0x00000000 VERNEED 0x00004564 VERNEEDNUM 0x00000002 VERSYM 0x000042d4 RELCOUNT 0x000000ac Version References: required from libstdc++.so.6: 0x056bafd3 0x00 05 CXXABI_1.3 0x08922974 0x00 04 GLIBCXX_3.4 required from libc.so.6: 0x0b792650 0x00 03 GCC_3.0 0x0d696910 0x00 02 GLIBC_2.0 In the recently compiled file I get: Program Header: LOAD off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12 filesz 0x00005300 memsz 0x00005300 flags r-x LOAD off 0x00005300 vaddr 0x00006300 paddr 0x00006300 align 2**12 filesz 0x00000274 memsz 0x00010314 flags rw- DYNAMIC off 0x00005314 vaddr 0x00006314 paddr 0x00006314 align 2**2 filesz 0x000000e0 memsz 0x000000e0 flags rw- EH_FRAME off 0x00004a00 vaddr 0x00004a00 paddr 0x00004a00 align 2**2 filesz 0x00000154 memsz 0x00000154 flags r-- Dynamic Section: NEEDED libstdc++.so.5 NEEDED libm.so.6 NEEDED libgcc_s.so.1 NEEDED libc.so.6 SONAME EpsonFiscalProtocol.so INIT 0x00001cb4 FINI 0x00004994 HASH 0x000000b4 STRTAB 0x00000da4 SYMTAB 0x000004f4 STRSZ 0x00000acf SYMENT 0x00000010 PLTGOT 0x0000640c PLTRELSZ 0x00000270 PLTREL 0x00000011 JMPREL 0x00001a44 REL 0x000019dc RELSZ 0x00000068 RELENT 0x00000008 VERNEED 0x0000198c VERNEEDNUM 0x00000002 VERSYM 0x00001874 RELCOUNT 0x00000004 Version References: required from libstdc++.so.5: 0x056bafd2 0x00 04 CXXABI_1.2 required from libc.so.6: 0x09691f73 0x00 03 GLIBC_2.1.3 0x0d696910 0x00 02 GLIBC_2.0 So I suspect the main diference is the GCC_3.0 symbol I compile libcom_tichile_EpsonSerialDriver.so with the following command ( from memory as I not at work right now ) g++ -Wl,-soname=.... -shared -I/*jni libraries*/ -o libcom_tichile_jpos_EpsonSerialDriver -lEpsonFiscalProtocol -lpthread Is there any way to tell g++ to use that symbol version? Or any idea in how to make it work? EDIT: I have another non-working version with the followin dump: Program Header: LOAD off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12 filesz 0x0000bf68 memsz 0x0000bf68 flags r-x LOAD off 0x0000cc0c vaddr 0x0000cc0c paddr 0x0000cc0c align 2**12 filesz 0x000005e8 memsz 0x00044df0 flags rw- DYNAMIC off 0x0000cc20 vaddr 0x0000cc20 paddr 0x0000cc20 align 2**2 filesz 0x000000f8 memsz 0x000000f8 flags rw- EH_FRAME off 0x0000b310 vaddr 0x0000b310 paddr 0x0000b310 align 2**2 filesz 0x000002bc memsz 0x000002bc flags r-- STACK off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2 filesz 0x00000000 memsz 0x00000000 flags rw- RELRO off 0x0000cc0c vaddr 0x0000cc0c paddr 0x0000cc0c align 2**0 filesz 0x000003f4 memsz 0x000003f4 flags r-- Dynamic Section: NEEDED EpsonFiscalProtocol.so NEEDED libpthread.so.0 NEEDED libstdc++.so.6 NEEDED libm.so.6 NEEDED libgcc_s.so.1 NEEDED libc.so.6 SONAME libcom_tichile_jpos_EpsonSerialDriver.so INIT 0x000055d8 FINI 0x0000a968 HASH 0x000000f4 GNU_HASH 0x00000a30 STRTAB 0x00002870 SYMTAB 0x00001410 STRSZ 0x00002339 SYMENT 0x00000010 PLTGOT 0x0000cff4 PLTRELSZ 0x00000168 PLTREL 0x00000011 JMPREL 0x00005470 REL 0x00004ea8 RELSZ 0x000005c8 RELENT 0x00000008 VERNEED 0x00004e38 VERNEEDNUM 0x00000002 VERSYM 0x00004baa RELCOUNT 0x00000001 Version References: required from libstdc++.so.6: 0x056bafd3 0x00 05 CXXABI_1.3 0x08922974 0x00 03 GLIBCXX_3.4 required from libc.so.6: 0x09691f73 0x00 06 GLIBC_2.1.3 0x0d696914 0x00 04 GLIBC_2.4 0x0d696910 0x00 02 GLIBC_2.0 Now I think the main difference is in the GCC_3.0 symbol/ABI EDIT: Luckily, a coworker found a way to talk to the printer using Java

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  • string maniupulations, oops, how do I replace parts of a string

    - by Joe Gibson
    I am very new to python. Could someone explain how I can manipulate a string like this? This function receives three inputs: complete_fmla: has a string with digits and symbols but has no hyphens ('-') nor spaces. partial_fmla: has a combination of hyphens and possibly some digits or symbols, where the digits and symbols that are in it (other than hyphens) are in the same position as in the complete_formula. symbol: one character The output that should be returned is: If the symbol is not in the complete formula, or if the symbol is already in the partial formula, the function should return the same formula as the input partial_formula. If the symbol is in the complete_formula and not in the partial formula, the function should return the partial_formula with the symbol substituting the hyphens in the positions where the symbol is, in all the occurrences of symbol in the complete_formula. For example: generate_next_fmla (‘abcdeeaa’, ‘- - - - - - - - ’, ‘d’) should return ‘- - - d - - - -’ generate_next_fmla (‘abcdeeaa’, ‘- - - d - - - - ’, ‘e’) should return ‘- - - d e e - -’ generate_next_fmla (‘abcdeeaa’, ‘- - - d e e - - ’, ‘a’) should return ‘a - - d e e a a’ Basically, I'm working with the definition: def generate_next_fmla (complete_fmla, partial_fmla, symbol): Do I turn them into lists? and then append? Also, should I find out the index number for the symbol in the complete_fmla so that I know where to append it in the string with hyphens??

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  • Ruby hpricot does not like dash in symbol, is there a workaround?

    - by eakkas
    I am trying to parse an xml file with hpricot. The xml element that I am trying to get has a dash though and hence the issue that I am facing xml <xliff xmlns="urn:oasis:names:tc:xliff:document:1.1" version="1.1"> <trans-unit> <source>"%0" can not be found. Please try again.</source> <target>"%0" can not be found. Please try again.</target> </trans-unit> </xliff> rb def read_in_xliff(xlf_file_name) stream = open(xlf_file_name) {|f| Hpricot(f)} (stream/:xliff/:'trans-unit').each do |transunit| .......... This does not work because of the dash. If I rename the tag to transunit and edit the symbol reference accordingly everything seems to be fine. I thought using the symbol between quotes should work but hpricot does not seem to like this. Can anyone think of a workaround? Thanks in advance

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  • C++ Deck and Card Class Error with bad alloc

    - by user3702164
    Just started learn to code in school. Our assignment requires us to create a card game with card,deck and hand class. I am having troubles with it now and i keep getting exception: std::bad_alloc at memory location. Here are my codes right now CardType h: #ifndef cardType_h #define cardType_h #include <string> using namespace std; class cardType{ public: void print(); int getValue() const; string getSymbol() const; string getSpecial() const; string getSuit() const; int checkSpecial(int gscore) const; cardType(); cardType(string suit,int value); private: int value; string special; string symbol; string suit; }; #endif CardType cpp: #include "cardType.h" #include <iostream> #include <string> using namespace std; void cardType::print() { cout << getSymbol() << " of " << getSuit() << ", having the value of " << getValue() << "."<< endl <<"This card's special is " << getSpecial() << endl; } int cardType::getValue() const { return value; } string cardType::getSymbol() const { return symbol; } string cardType::getSpecial() const { return special; } string cardType::getSuit() const { return suit; } cardType::cardType(){ value=0; symbol="?"; special='?'; suit='?'; } cardType::cardType(string s, int v){ suit = s; value = v; switch(v){ case 1: // Ace cards have a value of 1 and have no special type symbol="Ace"; special="None"; break; case 2: // 2 cards have a value of 2 and have no special type symbol="2"; special="None"; break; case 3: symbol="3"; // 3 cards have a value of 3 and have no special type special="None"; break; case 4: symbol="4"; // 4 cards have a value of 0 and have a special type "Reverse" which reverses the flow of the game special="Reverse"; value=0; break; case 5: symbol="5"; // 5 cards have a value of 5 and have no special type special="None"; break; case 6: symbol="6"; // 6 cards have a value of 6 and have no special type special="None"; break; case 7: symbol="7"; // 7 cards have a value of 7 and have no special type special="None"; break; case 8: symbol="8"; // 8 cards have a value of 8 and have no special type special="None"; break; case 9: symbol="9"; // 9 cards have a value of 0 and have a special type "Pass" which does not add any value to the game and lets the player skip his turn. special="Pass"; value=0; break; case 10: symbol="10"; // 10 cards have a value of 10 and have a special type "subtract" which instead of adding the 10 value to the total game it is subtracted instead. special="Subtract"; value=10; break; case 11: // Jack cards have a value of 10 and have no special type symbol="Jack"; special="None"; value=10; break; case 12: // Queens cards have a value of 10 and have no special type symbol="Queen"; special="None"; value=10; break; case 13: symbol="King"; // King cards have a value of 0 and have a special type "NinetyNine" which changes the total game score to 99 reguardless what number it was previously special="NinetyNine"; value=0; break; } } int cardType::checkSpecial(int gscore) const{ if(special=="Pass"){ return gscore; } if(special=="Reverse"){ return gscore; } if(special=="Subtract"){ return gscore - value; } if(special=="NinetyNine"){ return 99; } else{ return gscore + value; } } DeckType h: #ifndef deckType_h #define deckType_h #include "cardType.h" #include <string> using namespace std; class deckType { public: void shuffle(); cardType dealCard(); deckType(); private: cardType *deck; int current; }; #endif DeckType cpp: #include <iostream> #include "deckType.h" using namespace std; deckType::deckType() { int index = 0; int current=0; deck = new cardType[52]; string suit[] = {"Hearts","Diamonds","Clubs","Spades"}; int value[] = {1,2,3,4,5,6,7,8,9,10,11,12,13}; for ( int i = 0; i <= 3; i++ ) { for ( int j = 1; j <= 13; j++ ) { deck[index] = cardType(suit[i],value[j]); index++; } } } cardType deckType::dealCard() { return deck[current]; current++; } Main cpp : #include "deckType.h" #include <iostream> using namespace std; int main() { deckType gamedeck; cout << "1" <<endl; cardType currentCard; cout << "2" <<endl; currentCard = gamedeck.dealCard(); cout << "3" <<endl; return 0; } I keep getting bad_alloc at the currentCard = gamedeck.dealCard(); I really do not know what i have done wrong.

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  • C++ linker unresolved external symbol (again;) from other source file *.obj file. (VC++ express)

    - by bua
    Hi there, I'm back to C/C++ after some break. I've a following problem: I've a solution where I've several projects (compilable and linkable). Now I need to add another project to this solution which depends on some sources from other projects. My new project compiles without any problems (I've added "existing sources" to my project). the error: 1>Linking... 1>LicenceManager.obj : error LNK2019: unresolved external symbol "int __cdecl saveLic(char *,struct Auth *)" (?saveLic@@YAHPADPAUAuth@@@Z) referenced in function "public: void __thiscall LicenceManager::generateLicence(int,char *)" (?generateLicence@LicenceManager@@QAEXHPAD@Z) 1>LicenceManager.obj : error LNK2019: unresolved external symbol "void __cdecl getSysInfo(struct Auth *)" (?getSysInfo@@YAXPAUAuth@@@Z) referenced in function "public: void __thiscall LicenceManager::generateLicence(int,char *)" (?generateLicence@LicenceManager@@QAEXHPAD@Z) Functions saveLic, and getSysInfo are defined in files which I've added to my new project from existing ones. There is object file created during compilation with those functions in target dir, but my LicenceManager class doesn't want to link. I use some extern "C" , and #pragma pack somewhere, but no more fancy stuff. I think every directory, lib and other necessary dependencies are visible in settings for this project. Thanks for any advice.

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  • Retrieving database column using JSON [migrated]

    - by arokia
    I have a database consist of 4 columns (id-symbol-name-contractnumber). All 4 columns with their data are being displayed on the user interface using JSON. There is a function which is responisble to add new column to the database e.g (countrycode). The coulmn is added successfully to the database BUT not able to show the new added coulmn in the user interface. Below is my code that is displaying the columns. Can you help me? table.php $(document).ready(function () { // prepare the data var theme = getDemoTheme(); var source = { datatype: "json", datafields: [ { name: 'id' }, { name: 'symbol' }, { name: 'name' }, { name: 'contractnumber' } ], url: 'data.php', filter: function() { // update the grid and send a request to the server. $("#jqxgrid").jqxGrid('updatebounddata', 'filter'); }, cache: false }; var dataAdapter = new $.jqx.dataAdapter(source); // initialize jqxGrid $("#jqxgrid").jqxGrid( { source: dataAdapter, width: 670, theme: theme, showfilterrow: true, filterable: true, columns: [ { text: 'id', datafield: 'id', width: 200 }, { text: 'symbol', datafield: 'symbol', width: 200 }, { text: 'name', datafield: 'name', width: 100 }, { text: 'contractnumber', filtertype: 'list', datafield: 'contractnumber' } ] }); }); data.php <?php #Include the db.php file include('db.php'); $query = "SELECT * FROM pricelist"; $result = mysql_query($query) or die("SQL Error 1: " . mysql_error()); $orders = array(); // get data and store in a json array while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) { $pricelist[] = array( 'id' => $row['id'], 'symbol' => $row['symbol'], 'name' => $row['name'], 'contractnumber' => $row['contractnumber'] ); } echo json_encode($pricelist); ?>

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  • flash cs4: how to convert symbol to flex component?

    - by ufk
    Hiya I've read on the net that there is the flex component kit for flash that allows me to convert flash symbol to flex component or container. I tried installing Flex_Skins_12_05.mxp that suppose to enable these features in flash cs4 but under the commands tab i can't see any commands related to flex conversion. can someone please forward me to the appropriate plugin to install in flash cs4 in order to convert it's symbols to be usable with flex ? thanks

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  • How to fix unresolved external symbol due to MySql Connector C++?

    - by Chan
    Hi everyone, I followed this tutorial http://blog.ulf-wendel.de/?p=215#hello. I tried both on Visual C++ 2008 and Visual C++ 2010. Either static or dynamic, the compiler gave me the same exact error messages: error LNK2001: unresolved external symbol _get_driver_instance Has anyone experience this issue before? Update: + Additional Dependencies: mysqlcppconn.lib + Additional Include Directories: C:\Program Files\MySQL\MySQL Connector C++ 1.0.5\include + Additional Libraries Directories: C:\Program Files\MySQL\MySQL Connector C++ 1.0.5\lib\opt Thanks, Chan Nguyen

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  • How to handle duplicate symbol error from 3rd party libraries?

    - by brettr
    I have two 3rd party libraries that seem to use the same class. That should be fine but I'm getting this type of error when building: ld: duplicate symbol .objc_class_name_CJSONScanner in /Users/myappOne/TapjoyConnect/Frameworks/libTapjoyConnectSimulatorRewardInstall_Ads_Pinch.a(CJSONScanner.o) and /Developer/Projects/BuildOutput/Debug-iphonesimulator/OtherLibrary_d.a(CJSONScanner.o) How can I handle this issue?

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  • Under what conditions will you get unresolved external symbol for __declspec(dllimport)?

    - by Mark
    I am converting an application to use .dlls and I'm riddled with linker errors stating unersolved external symbol"__declspec(dllimport) public: void __thiscall Rail::SetNextrail(class Rail *)" There is more gibberish at the end of this error message. Why should this happen and how do you fix it? __declspec(dllimport) is being placed with a macro defined as: #ifdef LUDOAI_EXPORT #define DECLSPECAI __declspec(dllexport) #else #define DECLSPECAI __declspec(dllimport) #endif

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  • C#/.NET Little Wonders: The Useful But Overlooked Sets

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  Today we will be looking at two set implementations in the System.Collections.Generic namespace: HashSet<T> and SortedSet<T>.  Even though most people think of sets as mathematical constructs, they are actually very useful classes that can be used to help make your application more performant if used appropriately. A Background From Math In mathematical terms, a set is an unordered collection of unique items.  In other words, the set {2,3,5} is identical to the set {3,5,2}.  In addition, the set {2, 2, 4, 1} would be invalid because it would have a duplicate item (2).  In addition, you can perform set arithmetic on sets such as: Intersections: The intersection of two sets is the collection of elements common to both.  Example: The intersection of {1,2,5} and {2,4,9} is the set {2}. Unions: The union of two sets is the collection of unique items present in either or both set.  Example: The union of {1,2,5} and {2,4,9} is {1,2,4,5,9}. Differences: The difference of two sets is the removal of all items from the first set that are common between the sets.  Example: The difference of {1,2,5} and {2,4,9} is {1,5}. Supersets: One set is a superset of a second set if it contains all elements that are in the second set. Example: The set {1,2,5} is a superset of {1,5}. Subsets: One set is a subset of a second set if all the elements of that set are contained in the first set. Example: The set {1,5} is a subset of {1,2,5}. If We’re Not Doing Math, Why Do We Care? Now, you may be thinking: why bother with the set classes in C# if you have no need for mathematical set manipulation?  The answer is simple: they are extremely efficient ways to determine ownership in a collection. For example, let’s say you are designing an order system that tracks the price of a particular equity, and once it reaches a certain point will trigger an order.  Now, since there’s tens of thousands of equities on the markets, you don’t want to track market data for every ticker as that would be a waste of time and processing power for symbols you don’t have orders for.  Thus, we just want to subscribe to the stock symbol for an equity order only if it is a symbol we are not already subscribed to. Every time a new order comes in, we will check the list of subscriptions to see if the new order’s stock symbol is in that list.  If it is, great, we already have that market data feed!  If not, then and only then should we subscribe to the feed for that symbol. So far so good, we have a collection of symbols and we want to see if a symbol is present in that collection and if not, add it.  This really is the essence of set processing, but for the sake of comparison, let’s say you do a list instead: 1: // class that handles are order processing service 2: public sealed class OrderProcessor 3: { 4: // contains list of all symbols we are currently subscribed to 5: private readonly List<string> _subscriptions = new List<string>(); 6:  7: ... 8: } Now whenever you are adding a new order, it would look something like: 1: public PlaceOrderResponse PlaceOrder(Order newOrder) 2: { 3: // do some validation, of course... 4:  5: // check to see if already subscribed, if not add a subscription 6: if (!_subscriptions.Contains(newOrder.Symbol)) 7: { 8: // add the symbol to the list 9: _subscriptions.Add(newOrder.Symbol); 10: 11: // do whatever magic is needed to start a subscription for the symbol 12: } 13:  14: // place the order logic! 15: } What’s wrong with this?  In short: performance!  Finding an item inside a List<T> is a linear - O(n) – operation, which is not a very performant way to find if an item exists in a collection. (I used to teach algorithms and data structures in my spare time at a local university, and when you began talking about big-O notation you could immediately begin to see eyes glossing over as if it was pure, useless theory that would not apply in the real world, but I did and still do believe it is something worth understanding well to make the best choices in computer science). Let’s think about this: a linear operation means that as the number of items increases, the time that it takes to perform the operation tends to increase in a linear fashion.  Put crudely, this means if you double the collection size, you might expect the operation to take something like the order of twice as long.  Linear operations tend to be bad for performance because they mean that to perform some operation on a collection, you must potentially “visit” every item in the collection.  Consider finding an item in a List<T>: if you want to see if the list has an item, you must potentially check every item in the list before you find it or determine it’s not found. Now, we could of course sort our list and then perform a binary search on it, but sorting is typically a linear-logarithmic complexity – O(n * log n) - and could involve temporary storage.  So performing a sort after each add would probably add more time.  As an alternative, we could use a SortedList<TKey, TValue> which sorts the list on every Add(), but this has a similar level of complexity to move the items and also requires a key and value, and in our case the key is the value. This is why sets tend to be the best choice for this type of processing: they don’t rely on separate keys and values for ordering – so they save space – and they typically don’t care about ordering – so they tend to be extremely performant.  The .NET BCL (Base Class Library) has had the HashSet<T> since .NET 3.5, but at that time it did not implement the ISet<T> interface.  As of .NET 4.0, HashSet<T> implements ISet<T> and a new set, the SortedSet<T> was added that gives you a set with ordering. HashSet<T> – For Unordered Storage of Sets When used right, HashSet<T> is a beautiful collection, you can think of it as a simplified Dictionary<T,T>.  That is, a Dictionary where the TKey and TValue refer to the same object.  This is really an oversimplification, but logically it makes sense.  I’ve actually seen people code a Dictionary<T,T> where they store the same thing in the key and the value, and that’s just inefficient because of the extra storage to hold both the key and the value. As it’s name implies, the HashSet<T> uses a hashing algorithm to find the items in the set, which means it does take up some additional space, but it has lightning fast lookups!  Compare the times below between HashSet<T> and List<T>: Operation HashSet<T> List<T> Add() O(1) O(1) at end O(n) in middle Remove() O(1) O(n) Contains() O(1) O(n)   Now, these times are amortized and represent the typical case.  In the very worst case, the operations could be linear if they involve a resizing of the collection – but this is true for both the List and HashSet so that’s a less of an issue when comparing the two. The key thing to note is that in the general case, HashSet is constant time for adds, removes, and contains!  This means that no matter how large the collection is, it takes roughly the exact same amount of time to find an item or determine if it’s not in the collection.  Compare this to the List where almost any add or remove must rearrange potentially all the elements!  And to find an item in the list (if unsorted) you must search every item in the List. So as you can see, if you want to create an unordered collection and have very fast lookup and manipulation, the HashSet is a great collection. And since HashSet<T> implements ICollection<T> and IEnumerable<T>, it supports nearly all the same basic operations as the List<T> and can use the System.Linq extension methods as well. All we have to do to switch from a List<T> to a HashSet<T>  is change our declaration.  Since List and HashSet support many of the same members, chances are we won’t need to change much else. 1: public sealed class OrderProcessor 2: { 3: private readonly HashSet<string> _subscriptions = new HashSet<string>(); 4:  5: // ... 6:  7: public PlaceOrderResponse PlaceOrder(Order newOrder) 8: { 9: // do some validation, of course... 10: 11: // check to see if already subscribed, if not add a subscription 12: if (!_subscriptions.Contains(newOrder.Symbol)) 13: { 14: // add the symbol to the list 15: _subscriptions.Add(newOrder.Symbol); 16: 17: // do whatever magic is needed to start a subscription for the symbol 18: } 19: 20: // place the order logic! 21: } 22:  23: // ... 24: } 25: Notice, we didn’t change any code other than the declaration for _subscriptions to be a HashSet<T>.  Thus, we can pick up the performance improvements in this case with minimal code changes. SortedSet<T> – Ordered Storage of Sets Just like HashSet<T> is logically similar to Dictionary<T,T>, the SortedSet<T> is logically similar to the SortedDictionary<T,T>. The SortedSet can be used when you want to do set operations on a collection, but you want to maintain that collection in sorted order.  Now, this is not necessarily mathematically relevant, but if your collection needs do include order, this is the set to use. So the SortedSet seems to be implemented as a binary tree (possibly a red-black tree) internally.  Since binary trees are dynamic structures and non-contiguous (unlike List and SortedList) this means that inserts and deletes do not involve rearranging elements, or changing the linking of the nodes.  There is some overhead in keeping the nodes in order, but it is much smaller than a contiguous storage collection like a List<T>.  Let’s compare the three: Operation HashSet<T> SortedSet<T> List<T> Add() O(1) O(log n) O(1) at end O(n) in middle Remove() O(1) O(log n) O(n) Contains() O(1) O(log n) O(n)   The MSDN documentation seems to indicate that operations on SortedSet are O(1), but this seems to be inconsistent with its implementation and seems to be a documentation error.  There’s actually a separate MSDN document (here) on SortedSet that indicates that it is, in fact, logarithmic in complexity.  Let’s put it in layman’s terms: logarithmic means you can double the collection size and typically you only add a single extra “visit” to an item in the collection.  Take that in contrast to List<T>’s linear operation where if you double the size of the collection you double the “visits” to items in the collection.  This is very good performance!  It’s still not as performant as HashSet<T> where it always just visits one item (amortized), but for the addition of sorting this is a good thing. Consider the following table, now this is just illustrative data of the relative complexities, but it’s enough to get the point: Collection Size O(1) Visits O(log n) Visits O(n) Visits 1 1 1 1 10 1 4 10 100 1 7 100 1000 1 10 1000   Notice that the logarithmic – O(log n) – visit count goes up very slowly compare to the linear – O(n) – visit count.  This is because since the list is sorted, it can do one check in the middle of the list, determine which half of the collection the data is in, and discard the other half (binary search).  So, if you need your set to be sorted, you can use the SortedSet<T> just like the HashSet<T> and gain sorting for a small performance hit, but it’s still faster than a List<T>. Unique Set Operations Now, if you do want to perform more set-like operations, both implementations of ISet<T> support the following, which play back towards the mathematical set operations described before: IntersectWith() – Performs the set intersection of two sets.  Modifies the current set so that it only contains elements also in the second set. UnionWith() – Performs a set union of two sets.  Modifies the current set so it contains all elements present both in the current set and the second set. ExceptWith() – Performs a set difference of two sets.  Modifies the current set so that it removes all elements present in the second set. IsSupersetOf() – Checks if the current set is a superset of the second set. IsSubsetOf() – Checks if the current set is a subset of the second set. For more information on the set operations themselves, see the MSDN description of ISet<T> (here). What Sets Don’t Do Don’t get me wrong, sets are not silver bullets.  You don’t really want to use a set when you want separate key to value lookups, that’s what the IDictionary implementations are best for. Also sets don’t store temporal add-order.  That is, if you are adding items to the end of a list all the time, your list is ordered in terms of when items were added to it.  This is something the sets don’t do naturally (though you could use a SortedSet with an IComparer with a DateTime but that’s overkill) but List<T> can. Also, List<T> allows indexing which is a blazingly fast way to iterate through items in the collection.  Iterating over all the items in a List<T> is generally much, much faster than iterating over a set. Summary Sets are an excellent tool for maintaining a lookup table where the item is both the key and the value.  In addition, if you have need for the mathematical set operations, the C# sets support those as well.  The HashSet<T> is the set of choice if you want the fastest possible lookups but don’t care about order.  In contrast the SortedSet<T> will give you a sorted collection at a slight reduction in performance.   Technorati Tags: C#,.Net,Little Wonders,BlackRabbitCoder,ISet,HashSet,SortedSet

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  • Setting up Visual Studio 2010 to step into Microsoft .NET Source Code

    - by rajbk
    Using the Microsoft Symbol Server to obtain symbol debugging information is now much easier in VS 2010. Microsoft gives you access to their internet symbol server that contains symbol files for most of the .NET framework including the recently announced availability of MVC 2 Symbols.  SETUP In VS 2010 RTM, go to Tools –> Options –> Debugging –> General. Check “Enable .NET Framework source stepping” We get the following dialog box   This automatically disables “Enable My Code”   Go to Debugging –> Symbols and Check “Microsoft Symbol Servers”. You can selectively exclude modules if you want to.   You will get a warning dialog like so: Hitting OK will start the download process   The setup is complete. You are now ready to start debugging! DEBUGGING Add a break point to your application and run the application in debug mode (F5 shortcut for me). Go to your call stack when you hit the break point. Right click on a frame that is grayed out. Select “Load Symbols from” “Microsoft Symbol Servers”. VS will begin a one time download of that assembly. This assembly will be cached locally so you don’t have to wait for the download the next time you debug the app.   We get a one time license agreement dialog box You might see an error like the one below regarding different encoding (hopefully will be fixed).    Assemblies for which the symbols have been loaded are no longer grayed out. Double clicking on any entry in the call stack should now directly take you to the source code for that assembly. AFAIK, not all symbols are available on the MS symbol server. In cases like that you will see a tab like the one below and be given the option to “Show Disassembly”. Enjoy! Newsreel Announcer: Humiliated, Muntz vows a return to Paradise Falls and promises to capture the beast alive! Charles Muntz: [speaking to a large audience outside in the newsreel] I promise to capture the beast alive, and I will not come back until I do!

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  • Server 2003 SP2 BSOD caused by fltmgr.sys

    - by MasterMax1313
    I'm running into a problem where a Server 2003 SP2 box has started crashing roughly once an hour, BSODing out with the message that fltmgr.sys is probably the cause. I ran dumpchk.exe on the memory.dmp file, indicating the same thing. Any thoughts on typical root causes? The following is the error code I'm seeing: Error code 0000007e, parameter1 c0000005, parameter2 f723e087, parameter3 f78cea8c, parameter4 f78ce788. After running dumpchk on the memory.dmp file, I get the following note: Probably caused by : fltmgr.sys ( fltmgr!FltGetIrpName+63f ) The full log is here: Microsoft (R) Windows Debugger Version 6.12.0002.633 X86 Copyright (c) Microsoft Corporation. All rights reserved. Loading Dump File [c:\windows\memory.dmp] Kernel Complete Dump File: Full address space is available Symbol search path is: *** Invalid *** **************************************************************************** * Symbol loading may be unreliable without a symbol search path. * * Use .symfix to have the debugger choose a symbol path. * * After setting your symbol path, use .reload to refresh symbol locations. * **************************************************************************** Executable search path is: ********************************************************************* * Symbols can not be loaded because symbol path is not initialized. * * * * The Symbol Path can be set by: * * using the _NT_SYMBOL_PATH environment variable. * * using the -y <symbol_path> argument when starting the debugger. * * using .sympath and .sympath+ * ********************************************************************* *** ERROR: Symbol file could not be found. Defaulted to export symbols for ntkrnlpa.exe - Windows Server 2003 Kernel Version 3790 (Service Pack 2) UP Free x86 compatible Product: Server, suite: TerminalServer SingleUserTS Built by: 3790.srv03_sp2_gdr.101019-0340 Machine Name: Kernel base = 0x80800000 PsLoadedModuleList = 0x8089ffa8 Debug session time: Wed Oct 5 08:48:04.803 2011 (UTC - 4:00) System Uptime: 0 days 14:25:12.085 ********************************************************************* * Symbols can not be loaded because symbol path is not initialized. * * * * The Symbol Path can be set by: * * using the _NT_SYMBOL_PATH environment variable. * * using the -y <symbol_path> argument when starting the debugger. * * using .sympath and .sympath+ * ********************************************************************* *** ERROR: Symbol file could not be found. Defaulted to export symbols for ntkrnlpa.exe - Loading Kernel Symbols ............................................................... ................................................. Loading User Symbols Loading unloaded module list ... ******************************************************************************* * * * Bugcheck Analysis * * * ******************************************************************************* Use !analyze -v to get detailed debugging information. BugCheck 7E, {c0000005, f723e087, f78dea8c, f78de788} ***** Kernel symbols are WRONG. Please fix symbols to do analysis. *** ERROR: Symbol file could not be found. Defaulted to export symbols for fltmgr.sys - --omitted-- Probably caused by : fltmgr.sys ( fltmgr!FltGetIrpName+63f ) Followup: MachineOwner --------- ----- 32 bit Kernel Full Dump Analysis DUMP_HEADER32: MajorVersion 0000000f MinorVersion 00000ece KdSecondaryVersion 00000000 DirectoryTableBase 004e7000 PfnDataBase 81600000 PsLoadedModuleList 8089ffa8 PsActiveProcessHead 808a61c8 MachineImageType 0000014c NumberProcessors 00000001 BugCheckCode 0000007e BugCheckParameter1 c0000005 BugCheckParameter2 f723e087 BugCheckParameter3 f78dea8c BugCheckParameter4 f78de788 PaeEnabled 00000001 KdDebuggerDataBlock 8088e3e0 SecondaryDataState 00000000 ProductType 00000003 SuiteMask 00000110 Physical Memory Description: Number of runs: 3 (limited to 3) FileOffset Start Address Length 00001000 0000000000001000 0009e000 0009f000 0000000000100000 bfdf0000 bfe8f000 00000000bff00000 00100000 Last Page: 00000000bff8e000 00000000bffff000 KiProcessorBlock at 8089f300 1 KiProcessorBlock entries: ffdff120 Windows Server 2003 Kernel Version 3790 (Service Pack 2) UP Free x86 compatible Product: Server, suite: TerminalServer SingleUserTS Built by: 3790.srv03_sp2_gdr.101019-0340 Machine Name:*** ERROR: Module load completed but symbols could not be loaded for srv.sys Kernel base = 0x80800000 PsLoadedModuleList = 0x8089ffa8 Debug session time: Wed Oct 5 08:48:04.803 2011 (UTC - 4:00) System Uptime: 0 days 14:25:12.085 start end module name 80800000 80a50000 nt Tue Oct 19 10:00:49 2010 (4CBDA491) 80a50000 80a6f000 hal Sat Feb 17 00:48:25 2007 (45D69729) b83d4000 b83fe000 Fastfat Sat Feb 17 01:27:55 2007 (45D6A06B) b8476000 b84a1000 RDPWD Sat Feb 17 00:44:38 2007 (45D69646) b8549000 b8554000 TDTCP Sat Feb 17 00:44:32 2007 (45D69640) b8fe1000 b9045000 srv Thu Feb 17 11:58:17 2011 (4D5D53A9) b956d000 b95be000 HTTP Fri Nov 06 07:51:22 2009 (4AF41BCA) b9816000 b982d780 hgfs Tue Aug 12 20:36:54 2008 (48A22CA6) b9b16000 b9b20000 ndisuio Sat Feb 17 00:58:25 2007 (45D69981) b9cf6000 b9d1ac60 iwfsd Wed Sep 29 01:43:59 2004 (415A4B9F) b9e5b000 b9e62000 parvdm Tue Mar 25 03:03:49 2003 (3E7FFF55) b9e63000 b9e67860 lgtosync Fri Sep 12 04:38:13 2003 (3F6185F5) b9ed3000 b9ee8000 Cdfs Sat Feb 17 01:27:08 2007 (45D6A03C) b9f10000 b9f2e000 EraserUtilRebootDrv Thu Jul 07 21:45:11 2011 (4E166127) b9f2e000 b9f8c000 eeCtrl Thu Jul 07 21:45:11 2011 (4E166127) b9f8c000 b9f9d000 Fips Sat Feb 17 01:26:33 2007 (45D6A019) b9f9d000 ba013000 mrxsmb Fri Feb 18 10:22:23 2011 (4D5E8EAF) ba013000 ba043000 rdbss Wed Feb 24 10:54:03 2010 (4B854B9B) ba043000 ba0ad000 SPBBCDrv Mon Dec 14 23:39:00 2009 (4B2712E4) ba0ad000 ba0d7000 afd Thu Feb 10 08:42:18 2011 (4D53EB3A) ba0d7000 ba108000 netbt Sat Feb 17 01:28:57 2007 (45D6A0A9) ba108000 ba19c000 tcpip Sat Aug 15 05:53:38 2009 (4A8685A2) ba19c000 ba1b5000 ipsec Sat Feb 17 01:29:28 2007 (45D6A0C8) ba275000 ba288600 NAVENG Fri Jul 29 08:10:02 2011 (4E32A31A) ba289000 ba2ae000 SYMEVENT Thu Apr 15 21:31:23 2010 (4BC7BDEB) ba2ae000 ba42d300 NAVEX15 Fri Jul 29 08:07:28 2011 (4E32A280) ba42e000 ba479000 SRTSP Fri Mar 04 15:31:08 2011 (4D714C0C) ba485000 ba487b00 dump_vmscsi Wed Apr 11 13:55:32 2007 (461D2114) ba4e1000 ba540000 update Mon May 28 08:15:16 2007 (465AC7D4) ba568000 ba59f000 rdpdr Sat Feb 17 00:51:00 2007 (45D697C4) ba59f000 ba5b1000 raspptp Sat Feb 17 01:29:20 2007 (45D6A0C0) ba5b1000 ba5ca000 ndiswan Sat Feb 17 01:29:22 2007 (45D6A0C2) ba5da000 ba5e4000 dump_diskdump Sat Feb 17 01:07:44 2007 (45D69BB0) ba66a000 ba67e000 rasl2tp Sat Feb 17 01:29:02 2007 (45D6A0AE) ba67e000 ba69a000 VIDEOPRT Sat Feb 17 01:10:30 2007 (45D69C56) ba69a000 ba6c1000 ks Sat Feb 17 01:30:40 2007 (45D6A110) ba6c1000 ba6d5000 redbook Sat Feb 17 01:07:26 2007 (45D69B9E) ba6d5000 ba6ea000 cdrom Sat Feb 17 01:07:48 2007 (45D69BB4) ba6ea000 ba6ff000 serial Sat Feb 17 01:06:46 2007 (45D69B76) ba6ff000 ba717000 parport Sat Feb 17 01:06:42 2007 (45D69B72) ba717000 ba72a000 i8042prt Sat Feb 17 01:30:40 2007 (45D6A110) baff0000 baff3700 CmBatt Sat Feb 17 00:58:51 2007 (45D6999B) bf800000 bf9d3000 win32k Thu Mar 03 08:55:02 2011 (4D6F9DB6) bf9d3000 bf9ea000 dxg Sat Feb 17 01:14:39 2007 (45D69D4F) bf9ea000 bf9fec80 vmx_fb Sat Aug 16 07:23:10 2008 (48A6B89E) bf9ff000 bfa4a000 ATMFD Tue Feb 15 08:19:22 2011 (4D5A7D5A) bff60000 bff7e000 RDPDD Sat Feb 17 09:01:19 2007 (45D70AAF) f7214000 f723a000 KSecDD Mon Jun 15 13:45:11 2009 (4A3688A7) f723a000 f725f000 fltmgr Sat Feb 17 00:51:08 2007 (45D697CC) f725f000 f7272000 CLASSPNP Sat Feb 17 01:28:16 2007 (45D6A080) f7272000 f7283000 symmpi Mon Dec 13 16:03:14 2004 (41BE0392) f7283000 f72a2000 SCSIPORT Sat Feb 17 01:28:41 2007 (45D6A099) f72a2000 f72bf000 atapi Sat Feb 17 01:07:34 2007 (45D69BA6) f72bf000 f72e9000 volsnap Sat Feb 17 01:08:23 2007 (45D69BD7) f72e9000 f7315000 dmio Sat Feb 17 01:10:44 2007 (45D69C64) f7315000 f733c000 ftdisk Sat Feb 17 01:08:05 2007 (45D69BC5) f733c000 f7352000 pci Sat Feb 17 00:59:03 2007 (45D699A7) f7352000 f7386000 ACPI Sat Feb 17 00:58:47 2007 (45D69997) f7487000 f7490000 WMILIB Tue Mar 25 03:13:00 2003 (3E80017C) f7497000 f74a6000 isapnp Sat Feb 17 00:58:57 2007 (45D699A1) f74a7000 f74b4000 PCIIDEX Sat Feb 17 01:07:32 2007 (45D69BA4) f74b7000 f74c7000 MountMgr Sat Feb 17 01:05:35 2007 (45D69B2F) f74c7000 f74d2000 PartMgr Sat Feb 17 01:29:25 2007 (45D6A0C5) f74d7000 f74e7000 disk Sat Feb 17 01:07:51 2007 (45D69BB7) f74e7000 f74f3000 Dfs Sat Feb 17 00:51:17 2007 (45D697D5) f74f7000 f7501000 crcdisk Sat Feb 17 01:09:50 2007 (45D69C2E) f7507000 f7517000 agp440 Sat Feb 17 00:58:53 2007 (45D6999D) f7517000 f7522000 TDI Sat Feb 17 01:01:19 2007 (45D69A2F) f7527000 f7532000 ptilink Sat Feb 17 01:06:38 2007 (45D69B6E) f7537000 f7540000 raspti Sat Feb 17 00:59:23 2007 (45D699BB) f7547000 f7556000 termdd Sat Feb 17 00:44:32 2007 (45D69640) f7557000 f7561000 Dxapi Tue Mar 25 03:06:01 2003 (3E7FFFD9) f7577000 f7580000 mssmbios Sat Feb 17 00:59:12 2007 (45D699B0) f7587000 f7595000 NDProxy Wed Nov 03 09:25:59 2010 (4CD162E7) f75a7000 f75b1000 flpydisk Tue Mar 25 03:04:32 2003 (3E7FFF80) f75b7000 f75c0080 SRTSPX Fri Mar 04 15:31:24 2011 (4D714C1C) f75d7000 f75e3000 vga Sat Feb 17 01:10:30 2007 (45D69C56) f75e7000 f75f2000 Msfs Sat Feb 17 00:50:33 2007 (45D697A9) f75f7000 f7604000 Npfs Sat Feb 17 00:50:36 2007 (45D697AC) f7607000 f7615000 msgpc Sat Feb 17 00:58:37 2007 (45D6998D) f7617000 f7624000 netbios Sat Feb 17 00:58:29 2007 (45D69985) f7627000 f7634000 wanarp Sat Feb 17 00:59:17 2007 (45D699B5) f7637000 f7646000 intelppm Sat Feb 17 00:48:30 2007 (45D6972E) f7647000 f7652000 kbdclass Sat Feb 17 01:05:39 2007 (45D69B33) f7657000 f7661000 mouclass Tue Mar 25 03:03:09 2003 (3E7FFF2D) f7667000 f7671000 serenum Sat Feb 17 01:06:44 2007 (45D69B74) f7677000 f7682000 fdc Sat Feb 17 01:07:16 2007 (45D69B94) f7687000 f7694b00 vmx_svga Sat Aug 16 07:22:07 2008 (48A6B85F) f7697000 f76a0000 watchdog Sat Feb 17 01:11:45 2007 (45D69CA1) f76a7000 f76b0000 ndistapi Sat Feb 17 00:59:19 2007 (45D699B7) f76b7000 f76c6000 raspppoe Sat Feb 17 00:59:23 2007 (45D699BB) f76c8000 f7707000 NDIS Sat Feb 17 01:28:49 2007 (45D6A0A1) f7707000 f770f000 kdcom Tue Mar 25 03:08:00 2003 (3E800050) f770f000 f7717000 BOOTVID Tue Mar 25 03:07:58 2003 (3E80004E) f7717000 f771e000 intelide Sat Feb 17 01:07:32 2007 (45D69BA4) f771f000 f7726000 dmload Tue Mar 25 03:08:08 2003 (3E800058) f777f000 f7786000 dxgthk Tue Mar 25 03:05:52 2003 (3E7FFFD0) f7787000 f778e000 vmmemctl Tue Aug 12 20:37:25 2008 (48A22CC5) f77cf000 f77d6280 vmxnet Mon Sep 08 21:17:10 2008 (48C5CE96) f77d7000 f77df000 audstub Tue Mar 25 03:09:12 2003 (3E800098) f77ef000 f77f7000 Fs_Rec Tue Mar 25 03:08:36 2003 (3E800074) f77f7000 f77fe000 Null Tue Mar 25 03:03:05 2003 (3E7FFF29) f77ff000 f7806000 Beep Tue Mar 25 03:03:04 2003 (3E7FFF28) f7807000 f780f000 mnmdd Tue Mar 25 03:07:53 2003 (3E800049) f780f000 f7817000 RDPCDD Tue Mar 25 03:03:05 2003 (3E7FFF29) f7817000 f781f000 rasacd Tue Mar 25 03:11:50 2003 (3E800136) f7878000 f7897000 Mup Tue Apr 12 15:05:46 2011 (4DA4A28A) f7897000 f7899980 compbatt Sat Feb 17 00:58:51 2007 (45D6999B) f789b000 f789e900 BATTC Sat Feb 17 00:58:46 2007 (45D69996) f789f000 f78a1b00 vmscsi Wed Apr 11 13:55:32 2007 (461D2114) f79af000 f79b0280 vmmouse Mon Aug 11 07:16:51 2008 (48A01FA3) f79b1000 f79b2280 swenum Sat Feb 17 01:05:56 2007 (45D69B44) f7b4a000 f7bdf000 Ntfs Sat Feb 17 01:27:23 2007 (45D6A04B) Unloaded modules: ba65a000 ba668000 imapi.sys Timestamp: unavailable (00000000) Checksum: 00000000 ImageSize: 0000E000 ba1c4000 ba1d5000 vpc-8042.sys Timestamp: unavailable (00000000) Checksum: 00000000 ImageSize: 00011000 f77df000 f77e7000 Sfloppy.SYS Timestamp: unavailable (00000000) Checksum: 00000000 ImageSize: 00008000 ******************************************************************************* * * * Bugcheck Analysis * * * ******************************************************************************* Use !analyze -v to get detailed debugging information. BugCheck 7E, {c0000005, f723e087, f78dea8c, f78de788} ***** Kernel symbols are WRONG. Please fix symbols to do analysis. --omitted-- Probably caused by : fltmgr.sys ( fltmgr!FltGetIrpName+63f ) Followup: MachineOwner --------- Finished dump check

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  • Custom ASP.NET Routing to an HttpHandler

    - by Rick Strahl
    As of version 4.0 ASP.NET natively supports routing via the now built-in System.Web.Routing namespace. Routing features are automatically integrated into the HtttpRuntime via a few custom interfaces. New Web Forms Routing Support In ASP.NET 4.0 there are a host of improvements including routing support baked into Web Forms via a RouteData property available on the Page class and RouteCollection.MapPageRoute() route handler that makes it easy to route to Web forms. To map ASP.NET Page routes is as simple as setting up the routes with MapPageRoute:protected void Application_Start(object sender, EventArgs e) { RegisterRoutes(RouteTable.Routes); } void RegisterRoutes(RouteCollection routes) { routes.MapPageRoute("StockQuote", "StockQuote/{symbol}", "StockQuote.aspx"); routes.MapPageRoute("StockQuotes", "StockQuotes/{symbolList}", "StockQuotes.aspx"); } and then accessing the route data in the page you can then use the new Page class RouteData property to retrieve the dynamic route data information:public partial class StockQuote1 : System.Web.UI.Page { protected StockQuote Quote = null; protected void Page_Load(object sender, EventArgs e) { string symbol = RouteData.Values["symbol"] as string; StockServer server = new StockServer(); Quote = server.GetStockQuote(symbol); // display stock data in Page View } } Simple, quick and doesn’t require much explanation. If you’re using WebForms most of your routing needs should be served just fine by this simple mechanism. Kudos to the ASP.NET team for putting this in the box and making it easy! How Routing Works To handle Routing in ASP.NET involves these steps: Registering Routes Creating a custom RouteHandler to retrieve an HttpHandler Attaching RouteData to your HttpHandler Picking up Route Information in your Request code Registering routes makes ASP.NET aware of the Routes you want to handle via the static RouteTable.Routes collection. You basically add routes to this collection to let ASP.NET know which URL patterns it should watch for. You typically hook up routes off a RegisterRoutes method that fires in Application_Start as I did in the example above to ensure routes are added only once when the application first starts up. When you create a route, you pass in a RouteHandler instance which ASP.NET caches and reuses as routes are matched. Once registered ASP.NET monitors the routes and if a match is found just prior to the HttpHandler instantiation, ASP.NET uses the RouteHandler registered for the route and calls GetHandler() on it to retrieve an HttpHandler instance. The RouteHandler.GetHandler() method is responsible for creating an instance of an HttpHandler that is to handle the request and – if necessary – to assign any additional custom data to the handler. At minimum you probably want to pass the RouteData to the handler so the handler can identify the request based on the route data available. To do this you typically add  a RouteData property to your handler and then assign the property from the RouteHandlers request context. This is essentially how Page.RouteData comes into being and this approach should work well for any custom handler implementation that requires RouteData. It’s a shame that ASP.NET doesn’t have a top level intrinsic object that’s accessible off the HttpContext object to provide route data more generically, but since RouteData is directly tied to HttpHandlers and not all handlers support it it might cause some confusion of when it’s actually available. Bottom line is that if you want to hold on to RouteData you have to assign it to a custom property of the handler or else pass it to the handler via Context.Items[] object that can be retrieved on an as needed basis. It’s important to understand that routing is hooked up via RouteHandlers that are responsible for loading HttpHandler instances. RouteHandlers are invoked for every request that matches a route and through this RouteHandler instance the Handler gains access to the current RouteData. Because of this logic it’s important to understand that Routing is really tied to HttpHandlers and not available prior to handler instantiation, which is pretty late in the HttpRuntime’s request pipeline. IOW, Routing works with Handlers but not with earlier in the pipeline within Modules. Specifically ASP.NET calls RouteHandler.GetHandler() from the PostResolveRequestCache HttpRuntime pipeline event. Here’s the call stack at the beginning of the GetHandler() call: which fires just before handler resolution. Non-Page Routing – You need to build custom RouteHandlers If you need to route to a custom Http Handler or other non-Page (and non-MVC) endpoint in the HttpRuntime, there is no generic mapping support available. You need to create a custom RouteHandler that can manage creating an instance of an HttpHandler that is fired in response to a routed request. Depending on what you are doing this process can be simple or fairly involved as your code is responsible based on the route data provided which handler to instantiate, and more importantly how to pass the route data on to the Handler. Luckily creating a RouteHandler is easy by implementing the IRouteHandler interface which has only a single GetHttpHandler(RequestContext context) method. In this method you can pick up the requestContext.RouteData, instantiate the HttpHandler of choice, and assign the RouteData to it. Then pass back the handler and you’re done.Here’s a simple example of GetHttpHandler() method that dynamically creates a handler based on a passed in Handler type./// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } Note that this code checks for a specific type of handler and if it matches assigns the RouteData to this handler. This is optional but quite a common scenario if you want to work with RouteData. If the handler you need to instantiate isn’t under your control but you still need to pass RouteData to Handler code, an alternative is to pass the RouteData via the HttpContext.Items collection:IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; requestContext.HttpContext.Items["RouteData"] = requestContext.RouteData; return handler; } The code in the handler implementation can then pick up the RouteData from the context collection as needed:RouteData routeData = HttpContext.Current.Items["RouteData"] as RouteData This isn’t as clean as having an explicit RouteData property, but it does have the advantage that the route data is visible anywhere in the Handler’s code chain. It’s definitely preferable to create a custom property on your handler, but the Context work-around works in a pinch when you don’t’ own the handler code and have dynamic code executing as part of the handler execution. An Example of a Custom RouteHandler: Attribute Based Route Implementation In this post I’m going to discuss a custom routine implementation I built for my CallbackHandler class in the West Wind Web & Ajax Toolkit. CallbackHandler can be very easily used for creating AJAX, REST and POX requests following RPC style method mapping. You can pass parameters via URL query string, POST data or raw data structures, and you can retrieve results as JSON, XML or raw string/binary data. It’s a quick and easy way to build service interfaces with no fuss. As a quick review here’s how CallbackHandler works: You create an Http Handler that derives from CallbackHandler You implement methods that have a [CallbackMethod] Attribute and that’s it. Here’s an example of an CallbackHandler implementation in an ashx.cs based handler:// RestService.ashx.cs public class RestService : CallbackHandler { [CallbackMethod] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } } CallbackHandler makes it super easy to create a method on the server, pass data to it via POST, QueryString or raw JSON/XML data, and then retrieve the results easily back in various formats. This works wonderful and I’ve used these tools in many projects for myself and with clients. But one thing missing has been the ability to create clean URLs. Typical URLs looked like this: http://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuote&symbol=msfthttp://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuotes&symbolList=msft,intc,gld,slw,mwe&format=xml which works and is clear enough, but also clearly very ugly. It would be much nicer if URLs could look like this: http://www.west-wind.com//WestwindWebtoolkit/Samples/StockQuote/msfthttp://www.west-wind.com/WestwindWebtoolkit/Samples/StockQuotes/msft,intc,gld,slw?format=xml (the Virtual Root in this sample is WestWindWebToolkit/Samples and StockQuote/{symbol} is the route)(If you use FireFox try using the JSONView plug-in make it easier to view JSON content) So, taking a clue from the WCF REST tools that use RouteUrls I set out to create a way to specify RouteUrls for each of the endpoints. The change made basically allows changing the above to: [CallbackMethod(RouteUrl="RestService/StockQuote/{symbol}")] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod(RouteUrl = "RestService/StockQuotes/{symbolList}")] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } where a RouteUrl is specified as part of the Callback attribute. And with the changes made with RouteUrls I can now get URLs like the second set shown earlier. So how does that work? Let’s find out… How to Create Custom Routes As mentioned earlier Routing is made up of several steps: Creating a custom RouteHandler to create HttpHandler instances Mapping the actual Routes to the RouteHandler Retrieving the RouteData and actually doing something useful with it in the HttpHandler In the CallbackHandler routing example above this works out to something like this: Create a custom RouteHandler that includes a property to track the method to call Set up the routes using Reflection against the class Looking for any RouteUrls in the CallbackMethod attribute Add a RouteData property to the CallbackHandler so we can access the RouteData in the code of the handler Creating a Custom Route Handler To make the above work I created a custom RouteHandler class that includes the actual IRouteHandler implementation as well as a generic and static method to automatically register all routes marked with the [CallbackMethod(RouteUrl="…")] attribute. Here’s the code:/// <summary> /// Route handler that can create instances of CallbackHandler derived /// callback classes. The route handler tracks the method name and /// creates an instance of the service in a predictable manner /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler type</typeparam> public class CallbackHandlerRouteHandler : IRouteHandler { /// <summary> /// Method name that is to be called on this route. /// Set by the automatically generated RegisterRoutes /// invokation. /// </summary> public string MethodName { get; set; } /// <summary> /// The type of the handler we're going to instantiate. /// Needed so we can semi-generically instantiate the /// handler and call the method on it. /// </summary> public Type CallbackHandlerType { get; set; } /// <summary> /// Constructor to pass in the two required components we /// need to create an instance of our handler. /// </summary> /// <param name="methodName"></param> /// <param name="callbackHandlerType"></param> public CallbackHandlerRouteHandler(string methodName, Type callbackHandlerType) { MethodName = methodName; CallbackHandlerType = callbackHandlerType; } /// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } /// <summary> /// Generic method to register all routes from a CallbackHandler /// that have RouteUrls defined on the [CallbackMethod] attribute /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler Type</typeparam> /// <param name="routes"></param> public static void RegisterRoutes<TCallbackHandler>(RouteCollection routes) { // find all methods var methods = typeof(TCallbackHandler).GetMethods(BindingFlags.Instance | BindingFlags.Public); foreach (var method in methods) { var attrs = method.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (attrs.Length < 1) continue; CallbackMethodAttribute attr = attrs[0] as CallbackMethodAttribute; if (string.IsNullOrEmpty(attr.RouteUrl)) continue; // Add the route routes.Add(method.Name, new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler)))); } } } The RouteHandler implements IRouteHandler, and its responsibility via the GetHandler method is to create an HttpHandler based on the route data. When ASP.NET calls GetHandler it passes a requestContext parameter which includes a requestContext.RouteData property. This parameter holds the current request’s route data as well as an instance of the current RouteHandler. If you look at GetHttpHandler() you can see that the code creates an instance of the handler we are interested in and then sets the RouteData property on the handler. This is how you can pass the current request’s RouteData to the handler. The RouteData object also has a  RouteData.RouteHandler property that is also available to the Handler later, which is useful in order to get additional information about the current route. In our case here the RouteHandler includes a MethodName property that identifies the method to execute in the handler since that value no longer comes from the URL so we need to figure out the method name some other way. The method name is mapped explicitly when the RouteHandler is created and here the static method that auto-registers all CallbackMethods with RouteUrls sets the method name when it creates the routes while reflecting over the methods (more on this in a minute). The important point here is that you can attach additional properties to the RouteHandler and you can then later access the RouteHandler and its properties later in the Handler to pick up these custom values. This is a crucial feature in that the RouteHandler serves in passing additional context to the handler so it knows what actions to perform. The automatic route registration is handled by the static RegisterRoutes<TCallbackHandler> method. This method is generic and totally reusable for any CallbackHandler type handler. To register a CallbackHandler and any RouteUrls it has defined you simple use code like this in Application_Start (or other application startup code):protected void Application_Start(object sender, EventArgs e) { // Register Routes for RestService CallbackHandlerRouteHandler.RegisterRoutes<RestService>(RouteTable.Routes); } If you have multiple CallbackHandler style services you can make multiple calls to RegisterRoutes for each of the service types. RegisterRoutes internally uses reflection to run through all the methods of the Handler, looking for CallbackMethod attributes and whether a RouteUrl is specified. If it is a new instance of a CallbackHandlerRouteHandler is created and the name of the method and the type are set. routes.Add(method.Name,           new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler) )) ); While the routing with CallbackHandlerRouteHandler is set up automatically for all methods that use the RouteUrl attribute, you can also use code to hook up those routes manually and skip using the attribute. The code for this is straightforward and just requires that you manually map each individual route to each method you want a routed: protected void Application_Start(objectsender, EventArgs e){    RegisterRoutes(RouteTable.Routes);}void RegisterRoutes(RouteCollection routes) { routes.Add("StockQuote Route",new Route("StockQuote/{symbol}",                     new CallbackHandlerRouteHandler("GetStockQuote",typeof(RestService) ) ) );     routes.Add("StockQuotes Route",new Route("StockQuotes/{symbolList}",                     new CallbackHandlerRouteHandler("GetStockQuotes",typeof(RestService) ) ) );}I think it’s clearly easier to have CallbackHandlerRouteHandler.RegisterRoutes() do this automatically for you based on RouteUrl attributes, but some people have a real aversion to attaching logic via attributes. Just realize that the option to manually create your routes is available as well. Using the RouteData in the Handler A RouteHandler’s responsibility is to create an HttpHandler and as mentioned earlier, natively IHttpHandler doesn’t have any support for RouteData. In order to utilize RouteData in your handler code you have to pass the RouteData to the handler. In my CallbackHandlerRouteHandler when it creates the HttpHandler instance it creates the instance and then assigns the custom RouteData property on the handler:IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; Again this only works if you actually add a RouteData property to your handler explicitly as I did in my CallbackHandler implementation:/// <summary> /// Optionally store RouteData on this handler /// so we can access it internally /// </summary> public RouteData RouteData {get; set; } and the RouteHandler needs to set it when it creates the handler instance. Once you have the route data in your handler you can access Route Keys and Values and also the RouteHandler. Since my RouteHandler has a custom property for the MethodName to retrieve it from within the handler I can do something like this now to retrieve the MethodName (this example is actually not in the handler but target is an instance pass to the processor): // check for Route Data method name if (target is CallbackHandler) { var routeData = ((CallbackHandler)target).RouteData; if (routeData != null) methodToCall = ((CallbackHandlerRouteHandler)routeData.RouteHandler).MethodName; } When I need to access the dynamic values in the route ( symbol in StockQuote/{symbol}) I can retrieve it easily with the Values collection (RouteData.Values["symbol"]). In my CallbackHandler processing logic I’m basically looking for matching parameter names to Route parameters: // look for parameters in the routeif(routeData != null){    string parmString = routeData.Values[parameter.Name] as string;    adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType);} And with that we’ve come full circle. We’ve created a custom RouteHandler() that passes the RouteData to the handler it creates. We’ve registered our routes to use the RouteHandler, and we’ve utilized the route data in our handler. For completeness sake here’s the routine that executes a method call based on the parameters passed in and one of the options is to retrieve the inbound parameters off RouteData (as well as from POST data or QueryString parameters):internal object ExecuteMethod(string method, object target, string[] parameters, CallbackMethodParameterType paramType, ref CallbackMethodAttribute callbackMethodAttribute) { HttpRequest Request = HttpContext.Current.Request; object Result = null; // Stores parsed parameters (from string JSON or QUeryString Values) object[] adjustedParms = null; Type PageType = target.GetType(); MethodInfo MI = PageType.GetMethod(method, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); if (MI == null) throw new InvalidOperationException("Invalid Server Method."); object[] methods = MI.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (methods.Length < 1) throw new InvalidOperationException("Server method is not accessible due to missing CallbackMethod attribute"); if (callbackMethodAttribute != null) callbackMethodAttribute = methods[0] as CallbackMethodAttribute; ParameterInfo[] parms = MI.GetParameters(); JSONSerializer serializer = new JSONSerializer(); RouteData routeData = null; if (target is CallbackHandler) routeData = ((CallbackHandler)target).RouteData; int parmCounter = 0; adjustedParms = new object[parms.Length]; foreach (ParameterInfo parameter in parms) { // Retrieve parameters out of QueryString or POST buffer if (parameters == null) { // look for parameters in the route if (routeData != null) { string parmString = routeData.Values[parameter.Name] as string; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // GET parameter are parsed as plain string values - no JSON encoding else if (HttpContext.Current.Request.HttpMethod == "GET") { // Look up the parameter by name string parmString = Request.QueryString[parameter.Name]; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // POST parameters are treated as methodParameters that are JSON encoded else if (paramType == CallbackMethodParameterType.Json) //string newVariable = methodParameters.GetValue(parmCounter) as string; adjustedParms[parmCounter] = serializer.Deserialize(Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject( Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); } else if (paramType == CallbackMethodParameterType.Json) adjustedParms[parmCounter] = serializer.Deserialize(parameters[parmCounter], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject(parameters[parmCounter], parameter.ParameterType); parmCounter++; } Result = MI.Invoke(target, adjustedParms); return Result; } The code basically uses Reflection to loop through all the parameters available on the method and tries to assign the parameters from RouteData, QueryString or POST variables. The parameters are converted into their appropriate types and then used to eventually make a Reflection based method call. What’s sweet is that the RouteData retrieval is just another option for dealing with the inbound data in this scenario and it adds exactly two lines of code plus the code to retrieve the MethodName I showed previously – a seriously low impact addition that adds a lot of extra value to this endpoint callback processing implementation. Debugging your Routes If you create a lot of routes it’s easy to run into Route conflicts where multiple routes have the same path and overlap with each other. This can be difficult to debug especially if you are using automatically generated routes like the routes created by CallbackHandlerRouteHandler.RegisterRoutes. Luckily there’s a tool that can help you out with this nicely. Phill Haack created a RouteDebugging tool you can download and add to your project. The easiest way to do this is to grab and add this to your project is to use NuGet (Add Library Package from your Project’s Reference Nodes):   which adds a RouteDebug assembly to your project. Once installed you can easily debug your routes with this simple line of code which needs to be installed at application startup:protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); // Debug your routes RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes); } Any routed URL then displays something like this: The screen shows you your current route data and all the routes that are mapped along with a flag that displays which route was actually matched. This is useful – if you have any overlap of routes you will be able to see which routes are triggered – the first one in the sequence wins. This tool has saved my ass on a few occasions – and with NuGet now it’s easy to add it to your project in a few seconds and then remove it when you’re done. Routing Around Custom routing seems slightly complicated on first blush due to its disconnected components of RouteHandler, route registration and mapping of custom handlers. But once you understand the relationship between a RouteHandler, the RouteData and how to pass it to a handler, utilizing of Routing becomes a lot easier as you can easily pass context from the registration to the RouteHandler and through to the HttpHandler. The most important thing to understand when building custom routing solutions is to figure out how to map URLs in such a way that the handler can figure out all the pieces it needs to process the request. This can be via URL routing parameters and as I did in my example by passing additional context information as part of the RouteHandler instance that provides the proper execution context. In my case this ‘context’ was the method name, but it could be an actual static value like an enum identifying an operation or category in an application. Basically user supplied data comes in through the url and static application internal data can be passed via RouteHandler property values. Routing can make your application URLs easier to read by non-techie types regardless of whether you’re building Service type or REST applications, or full on Web interfaces. Routing in ASP.NET 4.0 makes it possible to create just about any extensionless URLs you can dream up and custom RouteHanmdler References Sample ProjectIncludes the sample CallbackHandler service discussed here along with compiled versionsof the Westwind.Web and Westwind.Utilities assemblies.  (requires .NET 4.0/VS 2010) West Wind Web Toolkit includes full implementation of CallbackHandler and the Routing Handler West Wind Web Toolkit Source CodeContains the full source code to the Westwind.Web and Westwind.Utilities assemblies usedin these samples. Includes the source described in the post.(Latest build in the Subversion Repository) CallbackHandler Source(Relevant code to this article tree in Westwind.Web assembly) JSONView FireFoxPluginA simple FireFox Plugin to easily view JSON data natively in FireFox.For IE you can use a registry hack to display JSON as raw text.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  HTTP  

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  • How would I strip an '&' symbol out of an ESRI dropdown before any of it's default control logic is

    - by Carter
    I have an ESRI dropdown control inside of an ESRI toolbar. One of the items in the dropdown needs to have an '&' symbol in it. As it turns out ESRI stuff builds it's callback strings as & delimited strings, so when an item is selected the parent toolbar immediately builds and handles the callback string. At one point it splits strings based on the '&' crashing the app. In effect, having an ampersand in an esri dropdown causes nasty stuff to happen when you select the item. What I need to do is find out how I can hop in before the callback stuff starts happening and strip that & out. I was thinking that perhaps I'd have to create a custom esri toolbar control, but I'm not sure and that'd be pretty undesirable. Any ideas?

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  • <function> referenced from; symbol(s) not found.

    - by jfm429
    I have a piece of C code that is used from a C++ function. At the top of my C++ file I have the line: #include "prediction.h" In prediction.h I have this: #ifndef prediction #define prediction #include "structs.h" typedef struct { double estimation; double variance; } response; response runPrediction(int obs, location* positions, double* observations, int targets, location* targetPositions); #endif I also have prediction.c, which has: #include "prediction.h" response runPrediction(int obs, location* positions, double* observations, int targets, location* targetPositions) { // code here } Now, in my C++ file (which as I said includes prediction.h) I call that function, then compile (through Xcode) I get this error: "runPrediction(int, location*, double*, int, location*)", referenced from: mainFrame::respondTo(char*, int)in mainFrame.o ld: symbol(s) not found collect2: ld returned 1 exit status prediction.c is marked for compilation for the current target. I don't have any problems with other .cpp files not being compiled. Any thoughts here?

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  • C errors - Cannot combine with previous 'struct' declaration specifier && Redefinition of 'MyMIDINotifyProc' as different kind of symbol

    - by user1905634
    I'm still new to C but trying to understand it better by working my way through a small MIDI audio unit (in Xcode 4.3.3). I've been searching for an answer to this all day and still don't even understand exactly what the problem is. Here's the code in question: //MyMIDINotifyProc.h #ifndef MIDIInstrumentUnit_CallbackProcs_h #define MIDIInstrumentUnit_CallbackProcs_h void MyMIDINotifyProc (const MIDINotification *message, void *refCon); #endif //MyMIDINotifyProc.c #include <CoreMIDI/CoreMIDI.h> #include "MyMIDINotifyProc.h" void MyMIDINotifyProc (const MIDINotification *message, void *refCon) { //manage notification } In the header definition I get this: ! Cannot combine with previous 'struct' declaration specifier I've made sure the definitions match and tried renaming them and I still get this in my .c file: ! Redefinition of 'MyMIDINotifyProc' as different kind of symbol Which points to the .h definition as the 'Previous definition'. I know that MIDIServices.h in the CoreMIDI framework defines: typedef void (*MIDINotifyProc)(const MIDINotification *message, void *refCon); But I don't understand if/why that would cause an error. I would be grateful if anyone could offer some help.

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