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  • C vs C++ function questions

    - by james
    I am learning C, and after starting out learning C++ as my first compiled language, I decided to "go back to basics" and learn C. There are two questions that I have concerning the ways each language deals with functions. Firstly, why does C "not care" about the scope that functions are defined in, whereas C++ does? For example, int main() { donothing(); return 0; } void donothing() { } the above will not compile in a C++ compiler, whereas it will compile in a C compiler. Why is this? Isn't C++ mostly just an extension on C, and should be mostly "backward compatible"? Secondly, the book that I found (Link to pdf) does not seem to state a return type for the main function. I check around and found other books and websites and these also commonly do not specify return types for the main function. If I try to compile a program that does not specify a return type for main, it compiles fine (although with some warnings) in a C compiler, but it doesn't compile in a C++ compiler. Again, why is that? Is it better style to always specify the return type as an integer rather than leaving it out? Thanks for any help, and just as a side note, if anyone can suggest a better book that I should buy that would be great!

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  • Selenium tests: html vs code?

    - by gustavogb
    Is it better to write/record selenium tests in html format and run them directly in the server with "-htmlSuite" or to write the tests in java/C#/... and run them in the server using selenium-rc? What is the recommended solution?

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  • Read vs Find -- Cakephp Usage

    - by Michael
    Hi all, I was reading through a book on CakePhp Application structure, and came across both the read and find functions. I've always only used find -- when would a read be appropriate? Examples appreciated. Thanks!

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  • Neural Network 0 vs -1

    - by Louis
    I have seen a few times people using -1 as opposed to 0 when working with neural networks for the input data. How is this better and does it effect any of the mathematics to implement it? Edit: Using feedforward and back prop Edit 2: I gave it a go but the network stopped learning so I assume the maths would have to change somewhere?

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  • Rails: update_attribute vs update_attributes

    - by Sam
    Object.update_attribute(:only_one_field, "Some Value") Object.update_attributes(:field1 => "value", :field2 => "value2", :field3 => "value3") Both of these will update an object without having to explicitly tell AR to update. Rails API says: for update_attribute Updates a single attribute and saves the record without going through the normal validation procedure. This is especially useful for boolean flags on existing records. The regular update_attribute method in Base is replaced with this when the validations module is mixed in, which it is by default. for update_attributes Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will fail and false will be returned. So if I don't want to have the object validated I should use update_attribute. What if I have this update on a before_save, will it stackoverflow? My question is does update_attribute also bypass the before save or just the validation. Also, what is the correct syntax to pass a hash to update_attributes... check out my example at the top.

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  • C# loop - break vs. continue

    - by Terrapin
    In a C# (feel free to answer for other languages) loop, what's the difference between break and continue as a means to leave the structure of the loop, and go to the next iteration? Example: foreach (DataRow row in myTable.Rows){ if (someConditionEvalsToTrue) { break; //what's the difference between this and continue ? //continue; }}

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  • Looking for an array (vs linked list) hashtable implementation in C

    - by kingusiu
    hi, I'm looking for a hashtable implementation in C that stores its objects in (twodimensional) arrays rather than linked lists. i.e. if a collision happens, the object that is causing the collision will be stored in the next free row index rather than pushed to the head and first element of a linked list. plus, the objects themselves must be copied to the hashtable, rather than referenced by pointers. (the objects do not live for the whole lifetime of the program but the table does). I know that such an implementation might have serious efficiency drawbacks and is not the "standard way of hashing" but as I work on a very special system-architecture i need those characteristics. thanks

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  • Cross-referencing UML models in VS 2010

    - by cheaster
    I am just starting to explore/use the UML modeling support in Visual Studio 2010 Umltimate. I have created two model projects within a single solution. Let's call them Model A and Model B. I have some data types (classes) defined in Model B. I want to use them as return types for operations in Model A. However, I cannot figure out how to make the types defined in Model B show up in Model A when attempting to set return type on an operation. Any help/suggestions would be greatly appreciated! Thanks!

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  • What VS 2010 Template to Chose?

    - by Dr Hydralisk
    I am just getting started with C++ and wanted to know does it really matter what template you chose in Visual Studio 2010 (for creating executables)? Like if I was creating a console application there is CLR Console Application, Win32 Console Application, and Win32 Project (description says it can be an application or a dll), what would I chose (or could i select Empty Project)?

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  • MySQL Integer vs DateTime index

    - by David Kuridža
    Let me start by saying I have looked at many similar questions asked, but all of them relate to Timestamp and DateTime field type without indexing. At least that is my understanding. As we all know, there are certain advantages when it comes to DateTime. Putting them aside for a minute, and assuming table's engine is InnoDB with 10+ million records, which query would perform faster when criteria is based on: DateTime with index int with index In other words, it is better to store date and time as DateTime or UNIX timestamp in int? Keep in mind there is no need for any built-in MySQL functions to be used.

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  • Zend_Search_Lucene vs SOLR

    - by spacemonkey
    Hi, I have recenlty stumbled into Zend Lucene port of Lucene project. I have a little bit experience with SOLR so I would like to know what is the difference between two of them especially from performance and installation side. As much as I know SOLR requires Tomcat serverlet running in web hosting in order to work, what about Zend Lucene library? I am also a bit confused what means "being implemented on the top of Lucene"?

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  • can't able to integrate base64decode in my class

    - by MaheshBabu
    Hi folks, i am getting the image that is in base64 encoded format. I need to decode it. i am writing the code for decoding is + (NSData *) base64DataFromString: (NSString *)string { unsigned long ixtext, lentext; unsigned char ch, input[4], output[3]; short i, ixinput; Boolean flignore, flendtext = false; const char *temporary; NSMutableData *result; if (!string) return [NSData data]; ixtext = 0; temporary = [string UTF8String]; lentext = [string length]; result = [NSMutableData dataWithCapacity: lentext]; ixinput = 0; while (true) { if (ixtext >= lentext) break; ch = temporary[ixtext++]; flignore = false; if ((ch >= 'A') && (ch <= 'Z')) ch = ch - 'A'; else if ((ch >= 'a') && (ch <= 'z')) ch = ch - 'a' + 26; else if ((ch >= '0') && (ch <= '9')) ch = ch - '0' + 52; else if (ch == '+') ch = 62; else if (ch == '=') flendtext = true; else if (ch == '/') ch = 63; else flignore = true; if (!flignore) { short ctcharsinput = 3; Boolean flbreak = false; if (flendtext) { if (ixinput == 0) break; if ((ixinput == 1) || (ixinput == 2)) { ctcharsinput = 1; else ctcharsinput = 2; ixinput = 3; flbreak = true; } input[ixinput++] = ch; if (ixinput == 4) ixinput = 0; output[0] = (input[0] << 2) | ((input[1] & 0x30) >> 4); output[1] = ((input[1] & 0x0F) << 4) | ((input[2] & 0x3C) >> 2); output[2] = ((input[2] & 0x03) << 6) | (input[3] & 0x3F); for (i = 0; i < ctcharsinput; i++) [result appendBytes: &output[i] length: 1]; } if (flbreak) break; } return result; } i am calling this in my method like this NSData *data = [base64DataFromString:theXML]; theXML is encoded data. but it shows error decodeBase64 undeclared. How can i use this method. can any one pls help me. Thank u in advance.

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  • IllegalAccessError: cross-loader access from pre-verifed class in MapActivity

    - by flipper83
    I have a big problem. When I lauch my MapActivity this launch the ilegal argument. I think that i check all 1) add map.jar from api 3 to eclipse 2) I obtain a api key 3) In androidmanifest I have putted the uses-library and te internet permision 4) I launch the google api emulator for api 3. 5) I dont know that i can try. Please, any idea? this can't be too dificult, I can't belive. Sure that it is a stupid thing :S

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  • GUI output differs from local vs production

    - by user279521
    I am having a weird experience. I am dynamically creating a row of textboxes at runtime when the user clicks a button. However, on my local machine the text boxes appear correctly (example [TextBox1] [TextBox2] [TextBox3] [TextBox4] [TextBox5] [TextBox1] [TextBox2] [TextBox3] [TextBox4] [TextBox5] [TextBox1] [TextBox2] [TextBox3] [TextBox4] [TextBox5] When I run this app on the production, the output side-by-side is: [TextBox1][TextBox1] [TextBox2][TextBox2] [TextBox3][TextBox3] [TextBox4][TextBox4] The output should be one row of textboxes, then a second row of 5 text boxes Anyone experience this?

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  • Object Oriented vs Relational Databases

    - by Dan
    Objects oriented databases seem like a really cool idea to me, no need to worry about mapping your domain model to your database model, no messing around with sql or ORM tools. The way I understand it, relational DBs offer some advantages when there is massive amounts of data, and searching an indexing need to be done. To my mind 99% of websites are not massive, and enterprise issues never need to be thought about, so why arn't OO DBs more widely used?

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  • Localizing formatting functions instead of properties in VS.NET resources

    - by LexL
    I noticed that .NET framework uses formatting functions, generated the same way localizable string are. There is a resource file Resources.resx with resource string TestString. So you may use it in code like this: string localizableValue = Resources.TestString; Now, imagine you need a formattable localizable string, to use it in string.Format function. So everytime you use it, you have to write something like this: string localizableFormattedValue = string.Format(Resources.TestFormatString, someParam1, someParam2); The observation says that in .NET framework generated resource classes already include the above construction. So instead of string property, a string function is generated. The resulting code looks like this: string localizableFormattedValue = Resources.TestFormatString(someParam1, someParam2); The question is - how do they do this? Is it some custom Microsoft feature (resx generator) or I'm missing something obvious?

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  • Development Applications on big devices vs mobile phones: Similarities/Disimilarities

    - by Richard77
    Hello, I saw a news document on applications running in mobile devices. And, I believe that might be interesting for people where I live (Internet is not developed - but the cellphone networks are much better). So here are my questions: Where can I find documentation for beginners on that matter (And most importantly) Am I gonna be able to take advantage of acquired knowledge in .NET framework (C#, MVC, JQuery, XHTML, ...)? Am I gonna need my laptop or a special device to develop applications? Am I gonna need Visual Studio? And so on... Bref, What are similarities/dissimilarities between developments for applications running in big machines and those running on mobile phones? Thanks for helping

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  • Java iterative vs recursive

    - by user1389813
    Can anyone explain why the following recursive method is faster than the iterative one (Both are doing it string concatenation) ? Isn't the iterative approach suppose to beat up the recursive one ? plus each recursive call adds a new layer on top of the stack which can be very space inefficient. private static void string_concat(StringBuilder sb, int count){ if(count >= 9999) return; string_concat(sb.append(count), count+1); } public static void main(String [] arg){ long s = System.currentTimeMillis(); StringBuilder sb = new StringBuilder(); for(int i = 0; i < 9999; i++){ sb.append(i); } System.out.println(System.currentTimeMillis()-s); s = System.currentTimeMillis(); string_concat(new StringBuilder(),0); System.out.println(System.currentTimeMillis()-s); } I ran the program multiple time, and the recursive one always ends up 3-4 times faster than the iterative one. What could be the main reason there that is causing the iterative one slower ?

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  • Grails problem with nullable contraint in domain class

    - by xain
    Hi, I'm having the following problem with grails' 1.2.1 domain classes: When I set a constraint attr(nullable:true) and attr is int or bool, this condition isn't reflected in the db (postgresql 8.4). However, if attr is a String, the DB is consistent with the situation. Any hints ? Thanks

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  • sigwait in Linux (Fedora 13) vs OS X

    - by Silas
    So I'm trying to create a signal handler using pthreads which works on both OS X and Linux. The code below works on OS X but doesn't work on Fedora 13. The application is fairly simple. It spawns a pthread, registers SIGHUP and waits for a signal. After spawning the signal handler I block SIGHUP in the main thread so the signal should only be sent to the signal_handler thread. On OS X this works fine, if I compile, run and send SIGHUP to the process it prints "Got SIGHUP". On Linux it just kills the process (and prints Hangup). If I comment out the signal_handler pthread_create the application doesn't die. I know the application gets to the sigwait and blocks but instead of return the signal code it just kills the application. I ran the test using the following commands: g++ test.cc -lpthread -o test ./test & PID="$!" sleep 1 kill -1 "$PID" test.cc #include <pthread.h> #include <signal.h> #include <iostream> using namespace std; void *signal_handler(void *arg) { int sig; sigset_t set; sigemptyset(&set); sigaddset(&set, SIGHUP); while (true) { cout << "Wait for signal" << endl; sigwait(&set, &sig); if (sig == SIGHUP) { cout << "Got SIGHUP" << endl; } } } int main() { pthread_t handler; sigset_t set; // Create signal handler pthread_create(&handler, NULL, signal_handler, NULL); // Ignore SIGHUP in main thread sigfillset(&set); sigaddset(&set, SIGHUP); pthread_sigmask(SIG_BLOCK, &set, NULL); for (int i = 1; i < 5; i++) { cout << "Sleeping..." << endl; sleep(1); } pthread_join(handler, NULL); return 0; }

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  • Extended events vs Triggers Sql server 2008

    - by Prashant
    I have a requirement to copy whatever data is getting inserted or updated to a log table to show who updated and when. I was thinking of using triggers for the same. The reason being the insert needed not be only stored procedure but can also be packages. Can I use extended events for the same ?.

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