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• PROJECT HELP NEEDED. SOME BASIC CONCEPTS GREAT CONFUSION BECAUSE OF LACK OF PROPER MATERIAL PLEASE H

  - by user287745

  Task ATTENDENCE RECORDER AND MANAGEMENT SYSTEM IN DISTRIBUTED ENVIRONMENT ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Example implementation needed. a main server in each lab where the operator punches in the attendence of the student. =========================================================== scenerio:- a college, 10 departments, all departments have a computer lab with 60-100 computers, the computers within each lab are interconnected and all computers in any department have to dail to a particular number (THE NUMBER GIVEN BY THE COLLEGE INTERNET DEPARTMENT) to get connected to the internet. therefore safe to assume that there is a central location to which all the computers in the college are connected to. there is a 'students attendence portal' which can be accessed using internet explorer, students enter there id and get the particular attendence record regarding to the labs only. a description of the working is like:- 1) the user will select which department, which year has arrived to the lab 2) the selection will give the user a return of all the students name and there roll numbers belonging to that department; 'with a check box to "TICK MARK IF THE STUDENT IS PRESENT" ' 3) A SUBMIT BUTTON when pressed reads the 'id' of the checkbox to determine the "particular count number of the student" from that an id of the student is constructed and that id is inserted with a present. (there is also date and time and much more to normalize the db and to avoid conflicts and keep historic records etc but that you will have to assume) steps taken till this date:- ( please note we are not computer students, we are to select something of some other line as a project!, as you will read in my many post 'i" have designed small websites just out of liking. have never ever done any thing official to implement like this.) * have made the database fully normalized. * have made the website which does the functions required on the database. Testing :- deployed the db and site on a free aspspider server and it worked. tested from several computers. Now the problem please help thank youuuuuuuu a practical demonstration has to be done within the college network. no internet! we have been assigned a lab - 60 computers- to demonstrate. (please dont give replies as 60 computers only! is not a big deal one CPU can manage it. i know that; IT IS A HYPOTHETICAL SITUATION WHERE WE ASSUME THAT 60 IS NOT 60 BUT ITS LIKE 60,000 COMPUTERS) 1a) make a web server, yes iis and put files in www folder and configure server to run aspx files- although a link to a step by step guide will be appreciated)\ ? which version of windows should i ask for xp or win server 2000 something? 2a) make a database server. ( well yes install sql server 2005, okay but then what? just put the database file on a pc share it and append the connection string to the share? ) 3a) make the site accessible from the remaining computers ? http://localhost/sitename ? all users "being operators of the particular lab" have the right to edit, write or delete(in dispute), thereby any "users" who hate our program can make the database inconsistent by accessing te same record and doing different edits and then complaining? so how to prevent this? you know something like when the db table is being written to others can only read but not write.. one big confusion:- IN DISTRIBUTED ENVIRONMENT "how to implement this" where does "distributed environment" come in! meaning :- alright the labs are in different departments but the "database server will be one" the "web server will be one" so whats distributed!?

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• Atomikos rollback doesn't clear JPA persistence context?

  - by HDave

  I have a Spring/JPA/Hibernate application and am trying to get it to pass my Junit integration tests against H2 and MySQL. Currently I am using Atomikos for transactions and C3P0 for connection pooling. Despite my best efforts my DAO integration one of the tests is failing with org.hibernate.NonUniqueObjectException. In the failing test I create an object with the "new" operator, set the ID and call persist on it. @Test @Transactional public void save_UserTestDataNewObject_RecordSetOneLarger() { int expectedNumberRecords = 4; User newUser = createNewUser(); dao.persist(newUser); List<User> allUsers = dao.findAll(0, 1000); assertEquals(expectedNumberRecords, allUsers.size()); } In the previous testmethod I do the same thing (createNewUser() is a helper method that creates an object with the same ID everytime). I am sure that creating and persisting a second object with the same Id is the cause, but each test method is in own transaction and the object I created is bound to a private test method variable. I can even see in the logs that Spring Test and Atomikos are rolling back the transaction associated with each test method. I would have thought the rollback would have also cleared the persistence context too. On a hunch, I added an a call to dao.clear() at the beginning of the faulty test method and the problem went away!! So rollback doesn't clear the persistence context??? If not, then who does?? My EntityManagerFactory config is as follows: <bean id="myappTestLocalEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="myapp-core" /> <property name="persistenceUnitPostProcessors"> <bean class="com.myapp.core.persist.util.JtaPersistenceUnitPostProcessor"> <property name="jtaDataSource" ref="myappPersistTestJdbcDataSource" /> </bean> </property> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="true" /> <property name="database" value="$DS{hibernate.database}" /> <property name="databasePlatform" value="$DS{hibernate.dialect}" /> </bean> </property> <property name="jpaProperties"> <props> <prop key="hibernate.transaction.factory_class">com.atomikos.icatch.jta.hibernate3.AtomikosJTATransactionFactory</prop> <prop key="hibernate.transaction.manager_lookup_class">com.atomikos.icatch.jta.hibernate3.TransactionManagerLookup</prop> <prop key="hibernate.connection.autocommit">false</prop> <prop key="hibernate.format_sql">true"</prop> <prop key="hibernate.use_sql_comments">true</prop> </property> </bean>

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• Problem with memset after an instance of a user defined class is created and a file is opened

  - by Liberalkid

  I'm having a weird problem with memset, that was something to do with a class I'm creating before it and a file I'm opening in the constructor. The class I'm working with normally reads in an array and transforms it into another array, but that's not important. The class I'm working with is: #include <vector> #include <algorithm> using namespace std; class PreProcess { public: PreProcess(char* fileName,char* outFileName); void SortedOrder(); private: vector< vector<double > > matrix; void SortRow(vector<double> &row); char* newFileName; vector< pair<double,int> > rowSorted; }; The other functions aren't important, because I've stopped calling them and the problem persists. Essentially I've narrowed it down to my constructor: PreProcess::PreProcess(char* fileName,char* outFileName):newFileName(outFileName){ ifstream input(fileName); input.close(); //this statement is inconsequential } I also read in the file in my constructor, but I've found that the problem persists if I don't read in the matrix and just open the file. Essentially I've narrowed it down to if I comment out those two lines the memset works properly, otherwise it doesn't. Now to the context of the problem I'm having with it: I wrote my own simple wrapper class for matrices. It doesn't have much functionality, I just need 2D arrays in the next part of my project and having a class handle everything makes more sense to me. The header file: #include <iostream> using namespace std; class Matrix{ public: Matrix(int r,int c); int &operator()(int i,int j) {//I know I should check my bounds here return matrix[i*columns+j]; } ~Matrix(); const void Display(); private: int *matrix; const int rows; const int columns; }; Driver: #include "Matrix.h" #include <string> using namespace std; Matrix::Matrix(int r,int c):rows(r),columns(c) { matrix=new int[rows*columns]; memset(matrix,0,sizeof(matrix)); } const void Matrix::Display(){ for(int i=0;i<rows;i++){ for(int j=0;j<columns;j++) cout << (*this)(i,j) << " "; cout << endl; } } Matrix::~Matrix() { delete matrix; } My main program runs: PreProcess test1(argv[1],argv[2]); //test1.SortedOrder(); Matrix test(10,10); test.Display(); And when I run this with the input line uncommented I get: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371727776 32698 -1 0 0 0 0 0 6332656 0 -1 -1 0 0 6332672 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371732704 32698 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I really don't have a clue what's going on in memory to cause this, on a side note if I replace memset with: for(int i=0;i<rows*columns;i++) *(matrix+i) &= 0x0; Then it works perfectly, it also works if I don't open the file. If it helps I'm running GCC 64-bit version 4.2.4 on Ubuntu.I assume there's some functionality of memset that I'm not properly understanding.

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• Double Linked List Insertion Sorting Bug

  - by house

  Hello, I have implemented an insertion sort in a double link list (highest to lowest) from a file of 10,000 ints, and output to file in reverse order. To my knowledge I have implemented such a program, however I noticed in the ouput file, a single number is out of place. Every other number is in correct order. The number out of place is a repeated number, but the other repeats of this number are in correct order. Its just strange how this number is incorrectly placed. Also the unsorted number is only 6 places out of sync. I have looked through my program for days now with no idea where the problem lies, so I turn to you for help. Below is the code in question, (side note: can my question be deleted by myself? rather my colleges dont thieve my code, if not how can it be deleted?) void DLLIntStorage::insertBefore(int inValue, node *nodeB) { node *newNode; newNode = new node(); newNode->prev = nodeB->prev; newNode->next = nodeB; newNode->value = inValue; if(nodeB->prev==NULL) { this->front = newNode; } else { nodeB->prev->next = newNode; } nodeB->prev = newNode; } void DLLIntStorage::insertAfter(int inValue, node *nodeB) { node *newNode; newNode = new node(); newNode->next = nodeB->next; newNode->prev = nodeB; newNode->value = inValue; if(nodeB->next == NULL) { this->back = newNode; } else { nodeB->next->prev = newNode; } nodeB->next = newNode; } void DLLIntStorage::insertFront(int inValue) { node *newNode; if(this->front == NULL) { newNode = new node(); this->front = newNode; this->back = newNode; newNode->prev = NULL; newNode->next = NULL; newNode->value = inValue; } else { insertBefore(inValue, this->front); } } void DLLIntStorage::insertBack(int inValue) { if(this->back == NULL) { insertFront(inValue); } else { insertAfter(inValue, this->back); } } ifstream& operator>> (ifstream &in, DLLIntStorage &obj) { int readInt, counter = 0; while(!in.eof()) { if(counter==dataLength) //stops at 10,000 { break; } in >> readInt; if(obj.front != NULL ) { obj.insertion(readInt); } else { obj.insertBack(readInt); } counter++; } return in; } void DLLIntStorage::insertion(int inValue) { node* temp; temp = this->front; if(temp->value >= inValue) { insertFront(inValue); return; } else { while(temp->next!=NULL && temp!=this->back) { if(temp->value >= inValue) { insertBefore(inValue, temp); return; } temp = temp->next; } } if(temp == this->back) { insertBack(inValue); } } Thankyou for your time.

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• Have suggestions for these assembly mnemonics?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Are their any suggestions for this new assembly language?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller exit End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Are there any suggestions for these new assembly mnemonics?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Policy-based template design: How to access certain policies of the class?

  - by dehmann

  I have a class that uses several policies that are templated. It is called Dish in the following example. I store many of these Dishes in a vector (using a pointer to simple base class), but then I'd like to extract and use them. But I don't know their exact types. Here is the code; it's a bit long, but really simple: #include <iostream> #include <vector> struct DishBase { int id; DishBase(int i) : id(i) {} }; std::ostream& operator<<(std::ostream& out, const DishBase& d) { out << d.id; return out; } // Policy-based class: template<class Appetizer, class Main, class Dessert> class Dish : public DishBase { Appetizer appetizer_; Main main_; Dessert dessert_; public: Dish(int id) : DishBase(id) {} const Appetizer& get_appetizer() { return appetizer_; } const Main& get_main() { return main_; } const Dessert& get_dessert() { return dessert_; } }; struct Storage { typedef DishBase* value_type; typedef std::vector<value_type> Container; typedef Container::const_iterator const_iterator; Container container; Storage() { container.push_back(new Dish<int,double,float>(0)); container.push_back(new Dish<double,int,double>(1)); container.push_back(new Dish<int,int,int>(2)); } ~Storage() { // delete objects } const_iterator begin() { return container.begin(); } const_iterator end() { return container.end(); } }; int main() { Storage s; for(Storage::const_iterator it = s.begin(); it != s.end(); ++it){ std::cout << **it << std::endl; std::cout << "Dessert: " << *it->get_dessert() << std::endl; // ?? } return 0; } The tricky part is here, in the main() function: std::cout << "Dessert: " << *it->get_dessert() << std::endl; // ?? How can I access the dessert? I don't even know the Dessert type (it is templated), let alone the complete type of the object that I'm getting from the storage. This is just a toy example, but I think my code reduces to this. I'd just like to pass those Dish classes around, and different parts of the code will access different parts of it (in the example: its appetizer, main dish, or dessert).

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• Calling system commands from Perl

  - by Dan J

  In an older version of our code, we called out from Perl to do an LDAP search as follows: # Pass the base DN in via the ldapsearch-specific environment variable # (rather than as the "-b" paramater) to avoid problems of shell # interpretation of special characters in the DN. $ENV{LDAP_BASEDN} = $ldn; $lcmd = "ldapsearch -x -T -1 -h $gLdapServer" . <snip> " > $lworkfile 2>&1"; system($lcmd); if (($? != 0) || (! -e "$lworkfile")) { # Handle the error } The code above would result in a successful LDAP search, and the output of that search would be in the file $lworkfile. Unfortunately, we recently reconfigured openldap on this server so that a "BASE DC=" is specified in /etc/openldap/ldap.conf and /etc/ldap.conf. That change seems to mean ldapsearch ignores the LDAP_BASEDN environment variable, and so my ldapsearch fails. I've tried a couple of different fixes but without success so far: (1) I tried going back to using the "-b" argument to ldapsearch, but escaping the shell metacharacters. I started writing the escaping code: my $ldn_escaped = $ldn; $ldn_escaped =~ s/\/\\/g; $ldn_escaped =~ s/`/\`/g; $ldn_escaped =~ s/$/\$/g; $ldn_escaped =~ s/"/\"/g; That threw up some Perl errors because I haven't escaped those regexes properly in Perl (the line number matches the regex with the backticks in). Backticks found where operator expected at /tmp/mycommand line 404, at end of line At the same time I started to doubt this approach and looked for a better one. (2) I then saw some Stackoverflow questions (here and here) that suggested a better solution. Here's the code: print("Processing..."); # Pass the arguments to ldapsearch by invoking open() with an array. # This ensures the shell does NOT interpret shell metacharacters. my(@cmd_args) = ("-x", "-T", "-1", "-h", "$gLdapPool", "-b", "$ldn", <snip> ); $lcmd = "ldapsearch"; open my $lldap_output, "-|", $lcmd, @cmd_args; while (my $lline = <$lldap_output>) { # I can parse the contents of my file fine } $lldap_output->close; The two problems I am having with approach (2) are: a) Calling open or system with an array of arguments does not let me pass > $lworkfile 2>&1 to the command, so I can't stop the ldapsearch output being sent to screen, which makes my output look ugly: Processing...ldap_bind: Success (0) additional info: Success b) I can't figure out how to choose which location (i.e. path and file name) to the file handle passed to open, i.e. I don't know where $lldap_output is. Can I move/rename it, or inspect it to find out where it is (or is it not actually saved to disk)? Based on the problems with (2), this makes me think I should return back to approach (1), but I'm not quite sure how to

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• Random Complete System Unresponsiveness Running Mathematical Functions

  - by Computer Guru

  I have a program that loads a file (anywhere from 10MB to 5GB) a chunk at a time (ReadFile), and for each chunk performs a set of mathematical operations (basically calculates the hash). After calculating the hash, it stores info about the chunk in an STL map (basically <chunkID, hash>) and then writes the chunk itself to another file (WriteFile). That's all it does. This program will cause certain PCs to choke and die. The mouse begins to stutter, the task manager takes 2 min to show, ctrl+alt+del is unresponsive, running programs are slow.... the works. I've done literally everything I can think of to optimize the program, and have triple-checked all objects. What I've done: Tried different (less intensive) hashing algorithms. Switched all allocations to nedmalloc instead of the default new operator Switched from stl::map to unordered_set, found the performance to still be abysmal, so I switched again to Google's dense_hash_map. Converted all objects to store pointers to objects instead of the objects themselves. Caching all Read and Write operations. Instead of reading a 16k chunk of the file and performing the math on it, I read 4MB into a buffer and read 16k chunks from there instead. Same for all write operations - they are coalesced into 4MB blocks before being written to disk. Run extensive profiling with Visual Studio 2010, AMD Code Analyst, and perfmon. Set the thread priority to THREAD_MODE_BACKGROUND_BEGIN Set the thread priority to THREAD_PRIORITY_IDLE Added a Sleep(100) call after every loop. Even after all this, the application still results in a system-wide hang on certain machines under certain circumstances. Perfmon and Process Explorer show minimal CPU usage (with the sleep), no constant reads/writes from disk, few hard pagefaults (and only ~30k pagefaults in the lifetime of the application on a 5GB input file), little virtual memory (never more than 150MB), no leaked handles, no memory leaks. The machines I've tested it on run Windows XP - Windows 7, x86 and x64 versions included. None have less than 2GB RAM, though the problem is always exacerbated under lower memory conditions. I'm at a loss as to what to do next. I don't know what's causing it - I'm torn between CPU or Memory as the culprit. CPU because without the sleep and under different thread priorities the system performances changes noticeably. Memory because there's a huge difference in how often the issue occurs when using unordered_set vs Google's dense_hash_map. What's really weird? Obviously, the NT kernel design is supposed to prevent this sort of behavior from ever occurring (a user-mode application driving the system to this sort of extreme poor performance!?)..... but when I compile the code and run it on OS X or Linux (it's fairly standard C++ throughout) it performs excellently even on poor machines with little RAM and weaker CPUs. What am I supposed to do next? How do I know what the hell it is that Windows is doing behind the scenes that's killing system performance, when all the indicators are that the application itself isn't doing anything extreme? Any advice would be most welcome.

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• How to design a C / C++ library to be usable in many client languages?

  - by Brian Schimmel

  I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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• Do you have suggestions for these assembly mnemonics?

  - by Noctis Skytower

  Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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• Test whether pixel is inside the blobs for ofxOpenCV

  - by mia

  I am doing an application of the concept of the dodgeball and need to test of the pixel of the ball is in the blobs capture(which is the image of the player) I am stucked and ran out of idea of how to implement it. I manage to do a little progress which have the blobs but I not sure how to test it. Please help. I am a newbie who in a desperate condition. Thank you. This is some of my code. void testApp::setup(){ #ifdef _USE_LIVE_VIDEO vidGrabber.setVerbose(true); vidGrabber.initGrabber(widthS,heightS); #else vidPlayer.loadMovie("fingers.mov"); vidPlayer.play(); #endif widthS = 320; heightS = 240; colorImg.allocate(widthS,heightS); grayImage.allocate(widthS,heightS); grayBg.allocate(widthS,heightS); grayDiff.allocate(widthS,heightS); ////<---what I want bLearnBakground = true; threshold = 80; //////////circle////////////// counter = 0; radius = 0; circlePosX = 100; circlePosY=200; } void testApp::update(){ ofBackground(100,100,100); bool bNewFrame = false; #ifdef _USE_LIVE_VIDEO vidGrabber.grabFrame(); bNewFrame = vidGrabber.isFrameNew(); #else vidPlayer.idleMovie(); bNewFrame = vidPlayer.isFrameNew(); #endif if (bNewFrame){ if (bLearnBakground == true){ grayBg = grayImage; // the = sign copys the pixels from grayImage into grayBg (operator overloading) bLearnBakground = false; } #ifdef _USE_LIVE_VIDEO colorImg.setFromPixels(vidGrabber.getPixels(),widthS,heightS); #else colorImg.setFromPixels(vidPlayer.getPixels(),widthS,heightS); #endif grayImage = colorImg; grayDiff.absDiff(grayBg, grayImage); grayDiff.threshold(threshold); contourFinder.findContours(grayDiff, 20, (340*240)/3, 10, true); // find holes } ////////////circle//////////////////// counter = counter + 0.05f; if(radius>=50){ circlePosX = ofRandom(10,300); circlePosY = ofRandom(10,230); } radius = 5 + 3*(counter); } void testApp::draw(){ // draw the incoming, the grayscale, the bg and the thresholded difference ofSetColor(0xffffff); //white colour grayDiff.draw(10,10);// draw start from point (0,0); // we could draw the whole contour finder // or, instead we can draw each blob individually, // this is how to get access to them: for (int i = 0; i < contourFinder.nBlobs; i++){ contourFinder.blobs[i].draw(10,10); } ///////////////circle////////////////////////// //let's draw a circle: ofSetColor(0,0,255); char buffer[255]; float a = radius; sprintf(buffer,"radius = %i",a); ofDrawBitmapString(buffer, 120, 300); if(radius>=50) { ofSetColor(255,255,255); counter = 0; } else{ ofSetColor(255,0,0); } ofFill(); ofCircle(circlePosX,circlePosY,radius); }

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• STL find performs bettern than hand-crafter loop

  - by dusha

  Hello all, I have some question. Given the following C++ code fragment: #include <boost/progress.hpp> #include <vector> #include <algorithm> #include <numeric> #include <iostream> struct incrementor { incrementor() : curr_() {} unsigned int operator()() { return curr_++; } private: unsigned int curr_; }; template<class Vec> char const* value_found(Vec const& v, typename Vec::const_iterator i) { return i==v.end() ? "no" : "yes"; } template<class Vec> typename Vec::const_iterator find1(Vec const& v, typename Vec::value_type val) { return find(v.begin(), v.end(), val); } template<class Vec> typename Vec::const_iterator find2(Vec const& v, typename Vec::value_type val) { for(typename Vec::const_iterator i=v.begin(), end=v.end(); i<end; ++i) if(*i==val) return i; return v.end(); } int main() { using namespace std; typedef vector<unsigned int>::const_iterator iter; vector<unsigned int> vec; vec.reserve(10000000); boost::progress_timer pt; generate_n(back_inserter(vec), vec.capacity(), incrementor()); //added this line, to avoid any doubts, that compiler is able to // guess the data is sorted random_shuffle(vec.begin(), vec.end()); cout << "value generation required: " << pt.elapsed() << endl; double d; pt.restart(); iter found=find1(vec, vec.capacity()); d=pt.elapsed(); cout << "first search required: " << d << endl; cout << "first search found value: " << value_found(vec, found)<< endl; pt.restart(); found=find2(vec, vec.capacity()); d=pt.elapsed(); cout << "second search required: " << d << endl; cout << "second search found value: " << value_found(vec, found)<< endl; return 0; } On my machine (Intel i7, Windows Vista) STL find (call via find1) runs about 10 times faster than the hand-crafted loop (call via find2). I first thought that Visual C++ performs some kind of vectorization (may be I am mistaken here), but as far as I can see assembly does not look the way it uses vectorization. Why is STL loop faster? Hand-crafted loop is identical to the loop from the STL-find body. I was asked to post program's output. Without shuffle: value generation required: 0.078 first search required: 0.008 first search found value: no second search required: 0.098 second search found value: no With shuffle (caching effects): value generation required: 1.454 first search required: 0.009 first search found value: no second search required: 0.044 second search found value: no Many thanks, dusha. P.S. I return the iterator and write out the result (found or not), because I would like to prevent compiler optimization, that it thinks the loop is not required at all. The searched value is obviously not in the vector.

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• destructor and copy-constructor calling..(why does it get called at these times)

  - by sil3nt

  Hello there, I have the following code #include <iostream> using namespace std; class Object { public: Object(int id){ cout << "Construct(" << id << ")" << endl; m_id = id; } Object(const Object& obj){ cout << "Copy-construct(" << obj.m_id << ")" << endl; m_id = obj.m_id; } Object& operator=(const Object& obj){ cout << m_id << " = " << obj.m_id << endl; m_id = obj.m_id; return *this; } ~Object(){ cout << "Destruct(" << m_id << ")" << endl; } private: int m_id; }; Object func(Object var) { return var; } int main(){ Object v1(1); cout << "( a )" << endl; Object v2(2); v2 = v1; cout << "( b )" << endl; Object v4 = v1; Object *pv5; pv5 = &v1; pv5 = new Object(5); cout << "( c )" << endl; func(v1); cout << "( d )" << endl; delete pv5; } which outputs Construct(1) ( a ) Construct(2) 2 = 1 ( b ) Copy-construct(1) Construct(5) ( c ) Copy-construct(1) Copy-construct(1) Destruct(1) Destruct(1) ( d ) Destruct(5) Destruct(1) Destruct(1) Destruct(1) I have some issues with this, firstly why does Object v4 = v1; call the copy constructor and produce Copy-construct(1) after the printing of ( b ). Also after the printing of ( c ) the copy-constructor is again called twice?, Im not certain of how this function works to produce that Object func(Object var) { return var; } and just after that Destruct(1) gets called twice before ( d ) is printed. sorry for the long question, I'm confused with the above.

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• map<string, vector<string>> reassignment of vector value

  - by user2950936

  I am trying to write a program that takes lines from an input file, sorts the lines into 'signatures' for the purpose of combining all words that are anagrams of each other. I have to use a map, storing the 'signatures' as the keys and storing all words that match those signatures into a vector of strings. Afterwards I must print all words that are anagrams of each other on the same line. Here is what I have so far: #include <iostream> #include <string> #include <algorithm> #include <map> #include <fstream> using namespace std; string signature(const string&); void printMap(const map<string, vector<string>>&); int main(){ string w1,sig1; vector<string> data; map<string, vector<string>> anagrams; map<string, vector<string>>::iterator it; ifstream myfile; myfile.open("words.txt"); while(getline(myfile, w1)) { sig1=signature(w1); anagrams[sig1]=data.push_back(w1); //to my understanding this should always work, } //either by inserting a new element/key or //by pushing back the new word into the vector<string> data //variable at index sig1, being told that the assignment operator //cannot be used in this way with these data types myfile.close(); printMap(anagrams); return 0; } string signature(const string& w) { string sig; sig=sort(w.begin(), w.end()); return sig; } void printMap(const map& m) { for(string s : m) { for(int i=0;i<m->second.size();i++) cout << m->second.at(); cout << endl; } } The first explanation is working, didn't know it was that simple! However now my print function is giving me: prob2.cc: In function âvoid printMap(const std::map<std::basic_string<char>, std::vector<std::basic_string<char> > >&)â: prob2.cc:43:36: error: cannot bind âstd::basic_ostream<char>::__ostream_type {aka std::basic_ostream<char>}â lvalue to âstd::basic_ostream<char>&&â In file included from /opt/centos/devtoolset-1.1/root/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/iostream:40:0, Tried many variations and they always complain about binding void printMap(const map<string, vector<string>> &mymap) { for(auto &c : mymap) cout << c.first << endl << c.second << endl; }

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• Problems with passing an anonymous temporary function-object to a templatized constructor.

  - by Akanksh

  I am trying to attach a function-object to be called on destruction of a templatized class. However, I can not seem to be able to pass the function-object as a temporary. The warning I get is (if the comment the line xi.data = 5;): warning C4930: 'X<T> xi2(writer (__cdecl *)(void))': prototyped function not called (was a variable definition intended?) with [ T=int ] and if I try to use the constructed object, I get a compilation error saying: error C2228: left of '.data' must have class/struct/union I apologize for the lengthy piece of code, but I think all the components need to be visible to assess the situation. template<typename T> struct Base { virtual void run( T& ){} virtual ~Base(){} }; template<typename T, typename D> struct Derived : public Base<T> { virtual void run( T& t ) { D d; d(t); } }; template<typename T> struct X { template<typename R> X(const R& r) { std::cout << "X(R)" << std::endl; ptr = new Derived<T,R>(); } X():ptr(0) { std::cout << "X()" << std::endl; } ~X() { if(ptr) { ptr->run(data); delete ptr; } else { std::cout << "no ptr" << std::endl; } } Base<T>* ptr; T data; }; struct writer { template<typename T> void operator()( const T& i ) { std::cout << "T : " << i << std::endl; } }; int main() { { writer w; X<int> xi2(w); //X<int> xi2(writer()); //This does not work! xi2.data = 15; } return 0; }; The reason I am trying this out is so that I can "somehow" attach function-objects types with the objects without keeping an instance of the function-object itself within the class. Thus when I create an object of class X, I do not have to keep an object of class writer within it, but only a pointer to Base<T> (I'm not sure if I need the <T> here, but for now its there). The problem is that I seem to have to create an object of writer and then pass it to the constructor of X rather than call it like X<int> xi(writer(); I might be missing something completely stupid and obvious here, any suggestions?

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• How can I pipe two Perl CORE::system commands in a cross-platform way?

  - by Pedro Silva

  I'm writing a System::Wrapper module to abstract away from CORE::system and the qx operator. I have a serial method that attempts to connect command1's output to command2's input. I've made some progress using named pipes, but POSIX::mkfifo is not cross-platform. Here's part of what I have so far (the run method at the bottom basically calls system): package main; my $obj1 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{''}], input => ['input.txt'], description => 'Concatenate input.txt to STDOUT', ); my $obj2 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{'$_ = reverse $_}'}], description => 'Reverse lines of input input', output => { '>' => 'output' }, ); $obj1->serial( $obj2 ); package System::Wrapper; #... sub serial { my ($self, @commands) = @_; eval { require POSIX; POSIX->import(); require threads; }; my $tmp_dir = File::Spec->tmpdir(); my $last = $self; my @threads; push @commands, $self; for my $command (@commands) { croak sprintf "%s::serial: type of args to serial must be '%s', not '%s'", ref $self, ref $self, ref $command || $command unless ref $command eq ref $self; my $named_pipe = File::Spec->catfile( $tmp_dir, int \$command ); POSIX::mkfifo( $named_pipe, 0777 ) or croak sprintf "%s::serial: couldn't create named pipe %s: %s", ref $self, $named_pipe, $!; $last->output( { '>' => $named_pipe } ); $command->input( $named_pipe ); push @threads, threads->new( sub{ $last->run } ); $last = $command; } $_->join for @threads; } #... My specific questions: Is there an alternative to POSIX::mkfifo that is cross-platform? Win32 named pipes don't work, as you can't open those as regular files, neither do sockets, for the same reasons. 2. The above doesn't quite work; the two threads get spawned correctly, but nothing flows across the pipe. I suppose that might have something to do with pipe deadlocking or output buffering. What throws me off is that when I run those two commands in the actual shell, everything works as expected. Point 2 is solved; a -p fifo file test was not testing the correct file.

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• C++ Optimize if/else condition

  - by Heye

  I have a single line of code, that consumes 25% - 30% of the runtime of my application. It is a less-than comparator for an std::set (the set is implemented with a Red-Black-Tree). It is called about 180 Million times within 52 seconds. struct Entry { const float _cost; const long _id; // some other vars Entry(float cost, float id) : _cost(cost), _id(id) { } }; template<class T> struct lt_entry: public binary_function <T, T, bool> { bool operator()(const T &l, const T &r) const { // Most readable shape if(l._cost != r._cost) { return r._cost < l._cost; } else { return l._id < r._id; } } }; The entries should be sorted by cost and if the cost is the same by their id. I have many insertions for each extraction of the minimum. I thought about using Fibonacci-Heaps, but I have been told that they are theoretically nice, but suffer from high constants and are pretty complicated to implement. And since insert is in O(log(n)) the runtime increase is nearly constant with large n. So I think its okay to stick to the set. To improve performance I tried to express it in different shapes: return l._cost < r._cost || r._cost > l._cost || l._id < r._id; return l._cost < r._cost || (l._cost == r._cost && l._id < r._id); Even this: typedef union { float _f; int _i; } flint; //... flint diff; diff._f = (l._cost - r._cost); return (diff._i && diff._i >> 31) || l._id < r._id; But the compiler seems to be smart enough already, because I haven't been able to improve the runtime. I also thought about SSE but this problem is really not very applicable for SSE... The assembly looks somewhat like this: movss (%rbx),%xmm1 mov $0x1,%r8d movss 0x20(%rdx),%xmm0 ucomiss %xmm1,%xmm0 ja 0x410600 <_ZNSt8_Rb_tree[..]+96> ucomiss %xmm0,%xmm1 jp 0x4105fd <_ZNSt8_Rb_[..]_+93> jne 0x4105fd <_ZNSt8_Rb_[..]_+93> mov 0x28(%rdx),%rax cmp %rax,0x8(%rbx) jb 0x410600 <_ZNSt8_Rb_[..]_+96> xor %r8d,%r8d I have a very tiny bit experience with assembly language, but not really much. I thought it would be the best (only?) point to squeeze out some performance, but is it really worth the effort? Can you see any shortcuts that could save some cycles? The platform the code will run on is an ubuntu 12 with gcc 4.6 (-stl=c++0x) on a many-core intel machine. Only libraries available are boost, openmp and tbb. I am really stuck on this one, it seems so simple, but takes that much time. I have been crunching my head since days thinking how I could improve this line... Can you give me a suggestion how to improve this part, or is it already at its best?

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• Trying to convert string to datetime

  - by user1596472

  I am trying to restrict a user from entering a new record if the date requested already exits. I was trying to do a count to see if the table that the record would be placed in already has that date 1 or not 0. I have a calendar extender attached to a text box which has the date. I keep getting either a: String was not recognized as a valid DateTime. or Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.IConvertible'. depending on the different things I have tried. Here is my code. TextBox startd = (TextBox)(DetailsView1.FindControl("TextBox5")); TextBox endd = (TextBox)(DetailsView1.FindControl("TextBox7")); DropDownList lvtype = (DropDownList)(DetailsView1.FindControl("DropDownList6")); DateTime scheduledDate = DateTime.ParseExact(startd.Text, "dd/MM/yyyy", null); DateTime endDate = DateTime.ParseExact(endd.Text, "dd/MM/yyyy", null); DateTime newstartDate = Convert.ToDateTime(startd.Text); DateTime newendDate = Convert.ToDateTime(endd.Text); //foreach (DataRow row in sd.Tables[0].Rows) DateTime dt = newstartDate; while (dt <= newendDate) { //for retreiving from table Decimal sd = SelectCountDate(dt, lvtype.SelectedValue, countDate); String ndt = Convert.ToDateTime(dt).ToShortDateString(); // //start = string.CompareOrdinal(scheduledDate, ndt); // // end = string.CompareOrdinal(endDate, ndt); //trying to make say when leavetpe is greater than count 1 then throw error. if (sd > 0) { Response.Write("<script>alert('Date Already Requested');</script>"); } dt.AddDays(1); } ^^^ This version throws the: "String was not recognized as valid date type" error But if i replace the string with either of these : /*-----------------------Original------------------------------------ string scheduledDate = Convert.ToDateTime(endd).ToShortDateString(); string endDate = Convert.ToDateTime(endd).ToShortDateString(); -------------------------------------------------------------------*/ /*----------10-30--------------------------------------- DateTime scheduledDate = DateTime.Parse(startd.Text); DateTime endDate = DateTime.Parse(endd.Text); ------------------------------------------------------*/ I get the "Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.IConvertible'." error. I am just trying to stop a user from entering a record date that already exits. <InsertItemTemplate> <asp:TextBox ID="TextBox5" runat="server" Height="19px" Text='<%# Bind("lstdate", "{0:MM/dd/yyyy}") %>' Width="67px"></asp:TextBox> <asp:CalendarExtender ID="TextBox5_CalendarExtender" runat="server" Enabled="True" TargetControlID="TextBox5"> </asp:CalendarExtender> <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="TextBox5" ErrorMessage="*Leave Date Required" ForeColor="Red"></asp:RequiredFieldValidator> <br /> <asp:CompareValidator ID="CompareValidator18" runat="server" ControlToCompare="TextBox7" ControlToValidate="TextBox5" ErrorMessage="Leave date cannot be after start date" ForeColor="Red" Operator="LessThanEqual" ToolTip="Must choose start date before end date"></asp:CompareValidator> </InsertItemTemplate>

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• Reordering Variadic Parameters

  - by void-pointer

  I have come across the need to reorder a variadic list of parameters that is supplied to the constructor of a struct. After being reordered based on their types, the parameters will be stored as a tuple. My question is how this can be done so that a modern C++ compiler (e.g. g++-4.7) will not generate unnecessary load or store instructions. That is, when the constructor is invoked with a list of parameters of variable size, it efficiently pushes each parameter into place based on an ordering over the parameters' types. Here is a concrete example. Assume that the base type of every parameter (without references, rvalue references, pointers, or qualifiers) is either char, int, or float. How can I make it so that all the parameters of base type char appear first, followed by all of those of base type int (which leaves the parameters of base type float last). The relative order in which the parameters were given should not be violated within sublists of homogeneous base type. Example: foo::foo() is called with arguments float a, char&& b, const float& c, int&& d, char e. The tuple tupe is std::tuple<char, char, int, float, float>, and it is constructed like so: tuple_type{std::move(b), e, std::move(d), a, c}. Consider the struct defined below, and assume that the metafunction deduce_reordered_tuple_type is already implemented. How would you write the constructor so that it works as intended? If you think that the code for deduce_reodered_tuple_type, would be useful to you, I can provide it; it's a little long. template <class... Args> struct foo { // Assume that the metafunction deduce_reordered_tuple_type is defined. typedef typename deduce_reordered_tuple_type<Args...>::type tuple_type; tuple_type t_; foo(Args&&... args) : t_{reorder_and_forward_parameters<Args>(args)...} {} }; Edit 1 The technique I describe above does have applications in mathematical frameworks that make heavy use of expression templates, variadic templates, and metaprogramming in order to perform aggressive inlining. Suppose that you wish to define an operator that takes the product of several expressions, each of which may be passed by reference, reference to const, or rvalue reference. (In my case, the expressions are conditional probability tables and the operation is the factor product, but something like matrix multiplication works suitably as well.) You need access to the data provided by each expression in order to evaluate the product. Consequently, you must move the expressions passed as rvalue references, copy the expressions passed by reference to const, and take the addresses of expressions passed by reference. Using the technique I describe above now poses several benefits. Other expressions can use uniform syntax to access data elements from this expression, since all of the heavy-lifting metaprogramming work is done beforehand, within the class. We can save stack space by grouping the pointers together and storing the larger expressions towards the end of the tuple. Implementing certain types of queries becomes much easier (e.g. check whether any of the pointers stored in the tuple aliases a given pointer). Thank you very much for your help!

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• Can i use a switch to hold a function?

  - by TIMOTHY

  I have a 3 file program, basically teaching myself c++. I have an issue. I made a switch to use the math function. I need and put it in a variable, but for some reason I get a zero as a result. Also another issue, when I select 4 (divide) it crashes... Is there a reason? Main file: #include <iostream> #include "math.h" #include <string> using namespace std; int opersel; int c; int a; int b; string test; int main(){ cout << "Welcome to Math-matrix v.34"<< endl; cout << "Shall we begin?" <<endl; //ASK USER IF THEY ARE READY TO BEGIN string answer; cin >> answer; if(answer == "yes" || answer == "YES" || answer == "Yes") { cout << "excellent lets begin..." << endl; cout << "please select a operator..." << endl << endl; cout << "(1) + " << endl; cout << "(2) - " << endl; cout << "(3) * " << endl; cout << "(4) / " << endl; cin >> opersel; switch(opersel){ case 1: c = add(a,b); break; case 2: c = sub(a,b); break; case 3: c = multi(a,b); break; case 4: c = divide(a,b); break; default: cout << "error... retry" << endl; }// end retry cout << "alright, how please select first digit?" << endl; cin >> a; cout << "excellent... and your second?" << endl; cin >> b; cout << c; cin >> test; }else if (answer == "no" || answer == "NO" || answer == "No"){ }//GAME ENDS }// end of int main Here is my math.h file #ifndef MATH_H #define MATH_H int add(int a, int b); int sub(int a, int b); int multi(int a, int b); int divide(int a, int b); #endif Here is my math.cpp: int add(int a, int b) { return a + b; } int sub(int a, int b) { return a - b; } int multi(int a, int b) { return a * b; } int divide(int a, int b) { return a / b; } }// end of int main

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• Android: Retrieving Password via registered Email on My Server

  - by Raghavan'G'

  i am working on retrieving password to the user when he submits his mail id that he registered on my server. I need to check whether he entered correct registered id and give him response by sending password to his corresponding mail and set dialog as password sent to your mail or if he entered wrong mail id i have to show mail id not registered... Any Idea? This is my code... package com.soap; import java.util.regex.Matcher; import java.util.regex.Pattern; import org.ksoap2.SoapEnvelope; import org.ksoap2.serialization.PropertyInfo; import org.ksoap2.serialization.SoapObject; import org.ksoap2.serialization.SoapSerializationEnvelope; import org.ksoap2.transport.HttpTransportSE; import android.app.Activity; import android.app.Dialog; import android.app.ProgressDialog; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText public class Register extends Activity { /** Called when the activity is first created. */ // static Spinner operator = null; private static final String SOAP_ACTION = "......"; private static final String METHOD_NAME = "......"; private static final String NAMESPACE = "......"; private static final String URL = "My site"; private static final String TAG = "HELLO"; Thread t; ProgressDialog dialog; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.forgotpasswordpage); Button signin = (Button) findViewById(R.id.fpwdsubmit); signin.setOnClickListener(new OnClickListener() { public void onClick(View v) { showDialog(0); t = new Thread() { public void run() { register(); } }; t.start(); } }); } @Override protected Dialog onCreateDialog(int id) { switch (id) { case 0: { dialog = new ProgressDialog(this); dialog.setMessage("Please wait while connecting..."); dialog.setIndeterminate(true); dialog.setCancelable(true); return dialog; } } return null; } public void register() { Log.v(TAG, "Trying to Login"); EditText etxt_user = (EditText)findViewById(R.id.fpedtext); String email_id = etxt_user.getText().toString(); SoapObject request = new SoapObject(NAMESPACE, METHOD_NAME); request.addProperty("Email", email_id); Pattern EMAIL_ADDRESS_PATTERN =Pattern.compile( "[a-zA-Z0-9\\+\\.\\_\\%\\-\\+]{1,256}" + "\\@" + "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" + "(" + "\\." + "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}" + ")+"); Matcher matcher = EMAIL_ADDRESS_PATTERN.matcher(email_id); if(matcher.matches()){ Log.v(TAG, "Your email id is valid ="+email_id); // System.out.println("Your email id is valid ="+email); } else{ // System.out.println("enter valid email id"); Log.v(TAG, "enter valid email id" ); } SoapSerializationEnvelope soapEnvelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); soapEnvelope.dotNet = true; soapEnvelope.setOutputSoapObject(request); HttpTransportSE aht = new HttpTransportSE(URL); try { aht.setXmlVersionTag("<?xml version=\"1.0\" encoding=\"UTF-8\"?>"); aht.call(SOAP_ACTION, soapEnvelope); SoapObject resultsRequestSOAP = (SoapObject) soapEnvelope.bodyIn; Log.v("TAG", String.valueOf(resultsRequestSOAP)); } catch (Exception e) { e.printStackTrace(); } } }

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• "Undefined reference to"

  - by user1332364

  I know that there are a lot of questions somewhat related to this one, but they answers are a bit hard for me to make sense of. I'm receiving the following error for a few different lines of code: C:\Users\Jeff\AppData\Local\Temp\ccAixtmT.o:football.cpp:(.text+0x6f0): undefined reference to `Player::set_values(int, std::string, float)' From these blocks of code: class Player { int playerNum; string playerPos; float playerRank; public: void set_values(int, string, float); float get_rank(){ return playerRank; }; bool operator == (const Player &p1/*, const Player &p2*/) const { if(&p1.playerNum == &playerNum && &p1.playerPos == &playerPos && &p1.playerRank == &playerRank) return true; else return false; }; }; And this being the main function referencing the subclass: int main() { ifstream infile; infile.open ("input.txt", ifstream::in); int numTeams; string command; while(!infile.fail() && !infile.eof()){ infile >> numTeams; string name; Player p; int playNum; string playPos; float playRank; Player all[11]; float ranks[11]; Team allTeams[numTeams]; for(int i=0; i<numTeams; i++){ infile >> name; for(int j=0; j<11; j++){ infile >> playNum; infile >> playPos; infile >> playRank; if(playPos == "QB") p.set_values(playNum, playPos, (playRank*2.0)); else if(playPos == "RB") p.set_values(playNum, playPos, (playRank*1.5)); else if(playPos == "WR") p.set_values(playNum, playPos, (playRank/1.8)); else if(playPos == "TE") p.set_values(playNum, playPos, (playRank*1.1)); else if(playPos == "GD") p.set_values(playNum, playPos, (playRank/2.0)); else if(playPos == "TC") p.set_values(playNum, playPos, (playRank/2.2)); else if(playPos == "CR") p.set_values(playNum, playPos, (playRank/1.2)); all[j] = p; allTeams[i].set_values(all, name); } } infile >> command; if (command == "play"){ int t1; int t2; infile >> t1; infile >> t2; play(allTeams[t1], allTeams[t2]); } else { int t1; int p1; int t2; int p2; swap(allTeams[t1], allTeams[t1].get_player(p1), allTeams[t2], allTeams[t2].get_player(p2)); } } }

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• C++ linked list based tree structure. Sanely copy nodes between lists.

  - by krunk

  edit Clafification: The intention is not to remove the node from the original list. But to create an identical node (data and children wise) to the original and insert that into the new list. In other words, a "move" does not imply a "remove" from the original. endedit The requirements: Each Node in the list must contain a reference to its previous sibling Each Node in the list must contain a reference to its next sibling Each Node may have a list of child nodes Each child Node must have a reference to its parent node Basically what we have is a tree structure of arbitrary depth and length. Something like: -root(NULL) --Node1 ----ChildNode1 ------ChildOfChild --------AnotherChild ----ChildNode2 --Node2 ----ChildNode1 ------ChildOfChild ----ChildNode2 ------ChildOfChild --Node3 ----ChildNode1 ----ChildNode2 Given any individual node, you need to be able to either traverse its siblings. the children, or up the tree to the root node. A Node ends up looking something like this: class Node { Node* previoius; Node* next; Node* child; Node* parent; } I have a container class that stores these and provides STL iterators. It performs your typical linked list accessors. So insertAfter looks like: void insertAfter(Node* after, Node* newNode) { Node* next = after->next; after->next = newNode; newNode->previous = after; next->previous = newNode; newNode->next = next; newNode->parent = after->parent; } That's the setup, now for the question. How would one move a node (and its children etc) to another list without leaving the previous list dangling? For example, if Node* myNode exists in ListOne and I want to append it to listTwo. Using pointers, listOne is left with a hole in its list since the next and previous pointers are changed. One solution is pass by value of the appended Node. So our insertAfter method would become: void insertAfter(Node* after, Node newNode); This seems like an awkward syntax. Another option is doing the copying internally, so you'd have: void insertAfter(Node* after, const Node* newNode) { Node *new_node = new Node(*newNode); Node* next = after->next; after->next = new_node; new_node->previous = after; next->previous = new_node; new_node->next = next; new_node->parent = after->parent; } Finally, you might create a moveNode method for moving and prevent raw insertion or appending of a node that already has been assigned siblings and parents. // default pointer value is 0 in constructor and a operator bool(..) // is defined for the Node bool isInList(const Node* node) const { return (node->previous || node->next || node->parent); } // then in insertAfter and friends if(isInList(newNode) // throw some error and bail I thought I'd toss this out there and see what folks came up with.

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