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• Changing default compiler in Linux, using SCons

  - by ereOn

  On my Linux platform, I have several versions of gcc. Under usr/bin I have: gcc34 gcc44 gcc Here are some outputs: $ gcc --version gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-48) $ gcc44 --version gcc44 (GCC) 4.4.0 20090514 (Red Hat 4.4.0-6) I need to use the 4.4 version of gcc however the default seems to the 4.1 one. I there a way to replace /usr/bin/gcc and make gcc44 the default compiler not using a symlink to /usr/bin/gcc44 ? The reason why I can't use a symlink is because my code will have to be shipped in a RPM package using mock. mock creates a minimal linux installation from scratch and just install the specified dependencies before compiling my code in it. I cannot customize this "minimal installation". Ideally, the perfect solution would be to install an official RPM package that replaces gcc with gcc44 as the default compiler. Is there such a package ? Is this even possible/good ? Additional information I have to use SCons (a make alternative) and it doesn't let me specify the binary to use for gcc. I will also accept any answer that will tell me how to specify the gcc binary in my SConstruct file.

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• Problem with linking in gcc

  - by chitra

  I am compiling a program in which a header file is defined in multiple places. Contents of each of the header file is different, though the variable names are the same internal members within the structures are different . Now at the linking time it is picking up from a library file which belongs to a different header not the one which is used during compilation. Due to this I get an error at link time. Since there are so many libraries with the same name I don't know which library is being picked up. I have lot of oems and other customized libraries which are part of this build. I checked out the options in gcc which talks about selecting different library files to be included. But no where I am able to see an option which talks about which libraries are being picked up the linker. If the linker is able to find more than one library file name, then which does the linker pick up is something which I am not able to understand. I don't want to specify any path, rather I want to understand how the linker is resolving the multiple libraries that it is able to locate. I tried putting -v option, but that doesn't list out the path from which the gcc picks up the library. I am using gcc on linux. Any help in this regard is highly appreciated. Regards, Chitra

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• Doing without partial commits the "Mercurial way"

  - by David Moles

  Subversion shop considering switching to Mercurial, trying to figure out in advance what all the complaints from developers are going to be. There's one fairly common use case here that I can't see how to handle. I'm working on some largish feature, and I have a significant part of the code -- or possibly several significant parts of the code -- in pieces all over the garage floor, totally unsuitable for checkin, maybe not even compiling. An urgent bugfix request comes in. The fix is nice and local and doesn't touch any of the code I've been working on. I make the fix in my working copy. Now what? I've looked at "Mercurial cherry picking changes for commit" and "best practices in mercurial: branch vs. clone, and partial merges?" and all the suggestions seem to be extensions of varying complexity, from Record and Shelve to Queues. The fact that there apparently isn't any core functionality for this makes me suspect that in some sense this working style is Doing It Wrong. What would a Mercurial-like solution to this use case look like?

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• How to fix error - "@interface interfaceName : someEnumeration" gives error "cannot find interface '

  - by Paul V

  How can I solve "cannot find interface declaration 'someEnumeration', superclass of 'interfaceName'" error? What steps will reproduce the problem? Compiling Wsdl2ObjC Targeting groupwise.wsdl file Fixing non-valid file names of output csource code like ".h" + ".m" and objects inside source files Moving up one of the @interface BEFORE it was used futher in code! What is the expected output? Something working What do you see instead? 33 errors. "Inherited" from only 3 similar Inheritances of a typedef enum object by a class. All errors are typical: typedef enum types_StatusTrackingOptions { types_StatusTrackingOptions_none = 0, types_StatusTrackingOptions_None, types_StatusTrackingOptions_Delivered, types_StatusTrackingOptions_DeliveredAndOpened, types_StatusTrackingOptions_All, } types_StatusTrackingOptions; types_StatusTrackingOptions types_StatusTrackingOptions_enumFromString(NSString *string); NSString * types_StatusTrackingOptions_stringFromEnum(types_StatusTrackingOptions enumValue); @interface types_StatusTracking : types_StatusTrackingOptions { ... and here I'm having error "cannot find interface declaration for 'types_StatusTrackingOptions', superclass of 'types_StatusTracking'". What version of the product are you using? On what operating system? Wsdl2ObjC - rev 168, OS - Mac OS X 10.6.2, iPhone SDK - 3.2, Simulator - v. 3.1.2 - 3.1.3, wsdl - for GroupWise v.8, NDK released 2008-12-23, wsdl and xsd files are attached. P.S. GroupWise.wsdl + .xsd files could be downloaded from http://code.google.com/p/wsdl2objc/issues/detail?id=99

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• Visual Studio 2010 randomly unable to debug WCF service.

  - by rossisdead

  I'm running Visual Studio 2010 on a Windows 7 x64 machine, and occasionally VS is giving me the good old "The remote procedure could not be debugged.This usually indicates that debugging has not been enabled on the server" error that a lot of people ask about. My problem, though, is that it seems to only do this randomly(it can be anywhere from a few minutes to a few hours), and after I've made plenty of successful calls to the service already. It doesn't prevent the service from working. It still returns values and doesn't throw any errors. The only difference is that annoying dialog pops up everytime I start to debug my application. I should mention that I'm connecting the WCF service from a WPF application. If I launch the web site the service is part of, I don't get the dialog. A few of the things I've tried that do not work: Killing and restarting the server. Compiling the web server in x86 Enabling tracing, but couldn't find any problems. Is this just a bug in Visual Studio 2010, or is there something I'm missing?

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• Android Cursor strange behaviour

  - by sandis

  After many houres of bug searching in a big app, I have finally tracked down the bug. This logging captures the problem: Log.d(TAG,"buildList, DBresult.getInt(1): "+DBresult.getInt(1)); Log.d(TAG,"buildList, DBresult.getString(1): "+DBresult.getString(1)); Log.d(TAG,"buildList, DBresult.getInt(4): "+DBresult.getInt(4)); Log.d(TAG,"buildList, DBresult.getString(4): "+DBresult.getString(4)); The resulting output: 05-06 11:11:20.123: DEBUG/TodoList(18943): buildList, DBresult.getInt(1): 0 05-06 11:11:20.123: DEBUG/TodoList(18943): buildList, DBresult.getString(1): false 05-06 11:11:20.123: DEBUG/TodoList(18943): buildList, DBresult.getInt(4): 0 05-06 11:11:20.123: DEBUG/TodoList(18943): buildList, DBresult.getString(4): true There are no backgroung threads running. As you can see the problem is that '0' is interpreted as false on one occasion, and as true on another. Since I am completely lost on how this can happen, I dont know how to proceed. What could possibly result in such a behaviour? Both the columns are of the type "boolean", i.e a numeric in sqlite. Unfortunately the string returned is the correct value, while the integer is always 0. If I export the database to my computer and check it with SQlite Administrator I can see that the values are correctly set, it is only the getInt()-function that always returns 0. I know for a fact that this works in other apps I have coded, and I dont know why this has stopped working. I have tried compiling the code under 2.0, 2.0.1 and 2.1, and it always appears. I can make my app runnable again by getting boolean values like this: myBool= (DBresult.getString(0).equals("true")); but that is both ugly and not optimized. Any suggestions on what is causing this behaviour is welcome. Cheers,

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• How are two-dimensional arrays formatted in memory?

  - by Chris Cooper

  In C, I know I can dynamically allocate a two-dimensional array on the heap using the following code: int** someNumbers = malloc(arrayRows*sizeof(int*)); for (i = 0; i < arrayRows; i++) { someNumbers[i] = malloc(arrayColumns*sizeof(int)); } Clearly, this actually creates a one-dimensional array of pointers to a bunch of separate one-dimensional arrays of integers, and "The System" can figure you what I mean when I ask for: someNumbers[4][2]; But when I statically declare a 2D array, as in the following line...: int someNumbers[ARRAY_ROWS][ARRAY_COLUMNS]; ...does a similar structure get created on the stack, or is it of another form completely? (i.e. is it a 1D array of pointers? If not, what is it, and how do references to it get figured out?) Also, when I said, "The System," what is actually responsible for figuring that out? The kernel? Or does the C compiler sort it out while compiling?

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• Template compilation error in Sun Studio 12

  - by Jagannath

  We are migrating to Sun Studio 12.1 and with the new compiler [ CC: Sun C++ 5.10 SunOS_sparc 2009/06/03 ]. I am getting compilation error while compiling a code that compiled fine with earlier version of Sun Compiler [ CC: Sun WorkShop 6 update 2 C++ 5.3 2001/05/15 ]. This is the compilation error I get. "Sample.cc": Error: Could not find a match for LoopThrough(int[2]) needed in main(). 1 Error(s) detected. * Error code 1. CODE: #include <iostream> #define PRINT_TRACE(STR) \ std::cout << __FILE__ << ":" << __LINE__ << ":" << STR << "\n"; template<size_t SZ> void LoopThrough(const int(&Item)[SZ]) { PRINT_TRACE("Specialized version"); for (size_t index = 0; index < SZ; ++index) { std::cout << Item[index] << "\n"; } } /* template<typename Type, size_t SZ> void LoopThrough(const Type(&Item)[SZ]) { PRINT_TRACE("Generic version"); } */ int main() { { int arr[] = { 1, 2 }; LoopThrough(arr); } } If I uncomment the code with Generic version, the code compiles fine and the generic version is called. I don't see this problem with MSVC 2010 with extensions disabled and the same case with ideone here. The specialized version of the function is called. Now the question is, is this a bug in Sun Compiler ? If yes, how could we file a bug report ?

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• Help with Java Generics: Cannot use "Object" as argument for "? extends Object"

  - by AniDev

  Hello, I have the following code: import java.util.*; public class SellTransaction extends Transaction { private Map<String,? extends Object> origValueMap; public SellTransaction(Map<String,? extends Object> valueMap) { super(Transaction.Type.Sell); assignValues(valueMap); this.origValueMap=valueMap; } public SellTransaction[] splitTransaction(double splitAtQuantity) { Map<String,? extends Object> valueMapPart1=origValueMap; valueMapPart1.put(nameMappings[3],(Object)new Double(splitAtQuantity)); Map<String,? extends Object> valueMapPart2=origValueMap; valueMapPart2.put(nameMappings[3],((Double)origValueMap.get(nameMappings[3]))-splitAtQuantity); return new SellTransaction[] {new SellTransaction(valueMapPart1),new SellTransaction(valueMapPart2)}; } } The code fails to compile when I call valueMapPart1.put and valueMapPart2.put, with the error: The method put(String, capture#5-of ? extends Object) in the type Map is not applicable for the arguments (String, Object) I have read on the Internet about generics and wildcards and captures, but I still don't understand what is going wrong. My understanding is that the value of the Map's can be any class that extends Object, which I think might be redundant, because all classes extend Object. And I cannot change the generics to something like ? super Object, because the Map is supplied by some library. So why is this not compiling? Also, if I try to cast valueMap to Map<String,Object>, the compiler gives me that 'Unchecked conversion' warning. Thanks!

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• Any useful suggestions to figure out where memory is being free'd in a Win32 process?

  - by LeopardSkinPillBoxHat

  An application I am working with is exhibiting the following behaviour: During a particular high-memory operation, the memory usage of the process under Task Manager (Mem Usage stat) reaches a peak of approximately 2.5GB (Note: A registry key has been set to allow this, as usually there is a maximum of 2GB for a process under 32-bit Windows) After the operation is complete, the process size slowly starts decreasing at a rate of 1MB per second. I am trying to figure out the easiest way to quickly determine who is freeing this memory, and where it is being free'd. I am having trouble attaching a memory profiler to my code, and I don't particularly want to override the new/delete operators to track the allocations/deallocations (IOW, I want to do this without re-compiling my code). Can anyone offer any useful suggestions of how I could do this via the Visual Studio debugger? Update I should also mention that it's a multi-threaded application, so pausing the application and analysing the call stack through the debugger is not the most desirable option. I considered freezing different threads one at a time to see if the memory stops reducing, but I'm fairly certain this will cause the application to crash.

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• multiple definition in header file

  - by Jérôme

  Here is a small code-example from which I'd like to ask a question : complex.h : #ifndef COMPLEX_H #define COMPLEX_H #include <iostream> class Complex { public: Complex(float Real, float Imaginary); float real() const { return m_Real; }; private: friend std::ostream& operator<<(std::ostream& o, const Complex& Cplx); float m_Real; float m_Imaginary; }; std::ostream& operator<<(std::ostream& o, const Complex& Cplx) { return o << Cplx.m_Real << " i" << Cplx.m_Imaginary; } #endif // COMPLEX_H complex.cpp : #include "complex.h" Complex::Complex(float Real, float Imaginary) { m_Real = Real; m_Imaginary = Imaginary; } main.cpp : #include "complex.h" #include <iostream> int main() { Complex Foo(3.4, 4.5); std::cout << Foo << "\n"; return 0; } When compiling this code, I get the following error : multiple definition of operator<<(std::ostream&, Complex const&) I've found that making this fonction inline solves the problem, but I don't understand why. Why does the compiler complain about multiple definition ? My header file is guarded (with #define COMPLEX_H). And, if complaining about the operator<< fonction, why not complain about the public real() fonction, which is defined in the header as well ? And is there another solution as using the inline keyword ?

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• map operator [] operands

  - by Jamie Cook

  Hi all I have the following in a member function int tt = 6; vector<set<int>>& temp = m_egressCandidatesByDestAndOtMode[tt]; set<int>& egressCandidateStops = temp.at(dest); and the following declaration of a member variable map<int, vector<set<int>>> m_egressCandidatesByDestAndOtMode; However I get an error when compiling (Intel Compiler 11.0) 1>C:\projects\svn\bdk\Source\ZenithAssignment\src\Iteration\PtBranchAndBoundIterationOriginRunner.cpp(85): error: no operator "[]" matches these operands 1> operand types are: const std::map<int, std::vector<std::set<int, std::less<int>, std::allocator<int>>, std::allocator<std::set<int, std::less<int>, std::allocator<int>>>>, std::less<int>, std::allocator<std::pair<const int, std::vector<std::set<int, std::less<int>, std::allocator<int>>, std::allocator<std::set<int, std::less<int>, std::allocator<int>>>>>>> [ const int ] 1> vector<set<int>>& temp = m_egressCandidatesByDestAndOtMode[tt]; 1> ^ I know it's got to be something silly but I can't see what I've done wrong.

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• Can ScalaCheck/Specs warnings safely be ignored when using SBT with ScalaTest?

  - by pdbartlett

  I have a simple FunSuite-based ScalaTest: package pdbartlett.hello_sbt import org.scalatest.FunSuite class SanityTest extends FunSuite { test("a simple test") { assert(true) } test("a very slightly more complicated test - purposely fails") { assert(42 === (6 * 9)) } } Which I'm running with the following SBT project config: import sbt._ class HelloSbtProject(info: ProjectInfo) extends DefaultProject(info) { // Dummy action, just to show config working OK. lazy val solveQ = task { println("42"); None } // Managed dependencies val scalatest = "org.scalatest" % "scalatest" % "1.0" % "test" } However, when I runsbt test I get the following warnings: ... [info] == test-compile == [info] Source analysis: 0 new/modified, 0 indirectly invalidated, 0 removed. [info] Compiling test sources... [info] Nothing to compile. [warn] Could not load superclass 'org.scalacheck.Properties' : java.lang.ClassNotFoundException: org.scalacheck.Properties [warn] Could not load superclass 'org.specs.Specification' : java.lang.ClassNotFoundException: org.specs.Specification [warn] Could not load superclass 'org.specs.Specification' : java.lang.ClassNotFoundException: org.specs.Specification [info] Post-analysis: 3 classes. [info] == test-compile == For the moment I'm assuming these are just "noise" (caused by the unified test interface?) and that I can safely ignore them. But it is slightly annoying to some inner OCD part of me (though not so annoying that I'm prepared to add dependencies for the other frameworks). Is this a correct assumption, or are there subtle errors in my test/config code? If it is safe to ignore, is there any other way to suppress these errors, or do people routinely include all three frameworks so they can pick and choose the best approach for different tests? TIA, Paul. (ADDED: scala v2.7.7 and sbt v0.7.4)

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• iOS Simulator is black on app execution

  - by Terryn

  I am running xcode 5.1.1 and have been trying to learn objective C / iOS development. Right now whenever I try to run my code on the emulator (I do not have an actual device atm) it comes up with a black screen. Code can be found here. Compiling and running gives me the following error: 2014-08-23 10:42:57.429 Calculator[1862:60b] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<XYZViewController 0xe436640> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key didgetPressed.' *** First throw call stack: ( 0 CoreFoundation 0x017ed1e4 __exceptionPreprocess + 180 1 libobjc.A.dylib 0x0156c8e5 objc_exception_throw + 44 2 CoreFoundation 0x0187cfe1 -[NSException raise] + 17 3 Foundation 0x0122cd9e -[NSObject(NSKeyValueCoding) setValue:forUndefinedKey:] + 282 4 Foundation 0x011991d7 _NSSetUsingKeyValueSetter + 88 5 Foundation 0x01198731 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 267 6 Foundation 0x011fab0a -[NSObject(NSKeyValueCoding) setValue:forKeyPath:] + 412 7 UIKit 0x004e31f4 -[UIRuntimeOutletConnection connect] + 106 8 libobjc.A.dylib 0x0157e7de -[NSObject performSelector:] + 62 9 CoreFoundation 0x017e876a -[NSArray makeObjectsPerformSelector:] + 314 10 UIKit 0x004e1d4d -[UINib instantiateWithOwner:options:] + 1417 11 UIKit 0x0034a6f5 -[UIViewController _loadViewFromNibNamed:bundle:] + 280 12 UIKit 0x0034ae9d -[UIViewController loadView] + 302 13 UIKit 0x0034b0d3 -[UIViewController loadViewIfRequired] + 78 14 UIKit 0x0034b5d9 -[UIViewController view] + 35 15 UIKit 0x0026b267 -[UIWindow addRootViewControllerViewIfPossible] + 66 16 UIKit 0x0026b5ef -[UIWindow _setHidden:forced:] + 312 17 UIKit 0x0026b86b -[UIWindow _orderFrontWithoutMakingKey] + 49 18 UIKit 0x002763c8 -[UIWindow makeKeyAndVisible] + 65 19 UIKit 0x00226bc0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 2097 20 UIKit 0x0022b667 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824 21 UIKit 0x0023ff92 -[UIApplication handleEvent:withNewEvent:] + 3517 22 UIKit 0x00240555 -[UIApplication sendEvent:] + 85 23 UIKit 0x0022d250 _UIApplicationHandleEvent + 683 24 GraphicsServices 0x037e2f02 _PurpleEventCallback + 776 25 GraphicsServices 0x037e2a0d PurpleEventCallback + 46 26 CoreFoundation 0x01768ca5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53 27 CoreFoundation 0x017689db __CFRunLoopDoSource1 + 523 28 CoreFoundation 0x0179368c __CFRunLoopRun + 2156 29 CoreFoundation 0x017929d3 CFRunLoopRunSpecific + 467 30 CoreFoundation 0x017927eb CFRunLoopRunInMode + 123 31 UIKit 0x0022ad9c -[UIApplication _run] + 840 32 UIKit 0x0022cf9b UIApplicationMain + 1225 33 Calculator 0x00002c8d main + 141 34 libdyld.dylib 0x01e34701 start + 1 35 ??? 0x00000001 0x0 + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException (lldb) I have attempted the following things, and so far nothing has worked 1) checked the deployment info, it has the main interface set to main 2) double checked all break points to turn them off and disabled all of them through Debug-Disable Breakpoints 3) Reset Content and Settings on the iOS Simulator. 4) Checked the issue with the LLDB Debugger, however from what I have read the issue is no longer present with the 5.1.1 xcode. 5) checked the local host is still set to 127.0.0.1 Thanks! - Terryn

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• ContentPresenter within ControlTemplate cannot change attached dependency property

  - by happyclicker

  Why does the following simplified code not set the font-size of the TextBlock to 50? <Window.Resources> <ControlTemplate TargetType="ContentControl" x:Key="Test"> <ContentPresenter TextBlock.FontSize="50" /> </ControlTemplate> </Window.Resources> <Grid> <ContentControl Template="{StaticResource Test}"> <TextBlock>Test should be rendered big</TextBlock> </ContentControl> </Grid> If I change the value of the FontSize property, visual studio shows me the text in the size I want. After compiling or executing the app, the size of the textblock is always reset to its default size. I have also tested various versions with styles and embedded resources but I end always in the situation that I cannot set attached dp's from within a ControlTemplate that contains a ContentPresenter. Is this by design?

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• Adventures on Enterprise Library 5.0: Who moved my cheese (namespace)

  - by Junior Mayhé

  Jesus, Krishna, Budda! I've migrated to EntLib 5.0, but classes like ISymmetricCryptoProvider are not recognized anymore. Funny to say that Data, Logging and other blocks are working compiling fine. Here's the problematic class: using System; using System.Collections.Generic; using System.Text; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;//-->it's not working anymore using Microsoft.Practices.EnterpriseLibrary.Security.Cryptography;//-->it's not working anymore namespace MyClassLibrary.Security.EnterpriseLibrary { public sealed class Crypto { public static ISymmetricCryptoProvider MyProvider { get { //IConfigurationSource is not recognized either, neither SystemConfigurationSource IConfigurationSource cs = new SystemConfigurationSource(); SymmetricCryptoProviderFactory scpf = new SymmetricCryptoProviderFactory(cs); ISymmetricCryptoProvider p = scpf.CreateDefault(); return p; } } The references are fine on project too. I really don't know why this particular project it's causing too many trouble on VS2010! Older references were deleted, project was cleaned, rebuilt, but can't make it compile :-( The references are: Microsoft.Practices.EnterpriseLibrary.Common Microsoft.Practices.EnterpriseLibrary.Logging Microsoft.Practices.EnterpriseLibrary.Logging.Database Microsoft.Practices.EnterpriseLibrary.Security Microsoft.Practices.EnterpriseLibrary.Security.Cryptography Why some namespaces can be found while others can't?

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• PHP - print content from file after manipulation

  - by ludicco

  Hello there, I'm struggling trying to read a php file inside a php and do some manipulation..after that have the content as a string, but when I try to output that with echo or print all the php tags are literally included on the file. so here is my code: function compilePage($page,$path){ $contents = array(); $menu = getMenuFor($page); $file = file_get_contents($path); array_push($contents,$menu); array_push($contents,$file); return implode("\n",$contents); } and this will return a string like <div id="content> <h2>Here is my title</h2> <p><? echo "my body text"; ?></p> </div> but this will print exactly the content above not compiling the php on it. So, how can I render this "compilePage" making sure it returns a compiled php result and not just a plain text? Thanks in advance

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• Resources and techniques/methods for SCJP preparation ?

  - by BenoitParis

  I am passing the SCJP 6 exam in a month. I have the "SCJP Sun Certified Programmer for Java 6 Exam 310-065" book. It seems great for the exam. But I want your advice on this. Getting the closest possible to 100% would be great. I have found a site that answered some of the questions you ask yourself when you go trough the book. Here is it : http://www.janeg.ca/java2.html As you can see it was written for Java 2 :/ I have written another specific question here on StackOverflow about the usefulness of JVM specification and Java compiler code for the SCJP. Will Update the results here. Here it is. Please share the resources you used in preparing the exam. Please also specify any resources that you think might help. Any type of resource is welcome: books, code, specs, sites, wikies, papers, online tests, grandmas... Please also share on any method/technique that helped you prepare the exam. Please also comment on the return you got from the resource and the method (for the learning process and for points in the exam) I'll begin: Book : "SCJP Sun Certified Programmer for Java 6 Exam 310-065". Seems like the official book for the preparation. Technique : Writing code in a text editor and compiling it with javac to test a question. NO IDEs! It helps you get a a straight answer to a question you have. It helps you pay attention to every word in the code (and this is very important in the SCJP) EDIT: Added dimension: Are there good, up-to-date online tests?

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• What happens to class members when malloc is used instead of new?

  - by Felix

  I'm studying for a final exam and I stumbled upon a curious question that was part of the exam our teacher gave last year to some poor souls. The question goes something like this: Is the following program correct, or not? If it is, write down what the program outputs. If it's not, write down why. The program: #include<iostream.h> class cls { int x; public: cls() { x=23; } int get_x(){ return x; } }; int main() { cls *p1, *p2; p1=new cls; p2=(cls*)malloc(sizeof(cls)); int x=p1->get_x()+p2->get_x(); cout<<x; return 0; } My first instinct was to answer with "the program is not correct, as new should be used instead of malloc". However, after compiling the program and seeing it output 23 I realize that that answer might not be correct. The problem is that I was expecting p2->get_x() to return some arbitrary number (whatever happened to be in that spot of the memory when malloc was called). However, it returned 0. I'm not sure whether this is a coincidence or if class members are initialized with 0 when it is malloc-ed. Is this behavior (p2->x being 0 after malloc) the default? Should I have expected this? What would your answer to my teacher's question be? (besides forgetting to #include <stdlib.h> for malloc :P)

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• Importing external .jar file to Android project

  - by robintw

  I've read various answers to similar questions on StackOverflow, so I apologise if I'm repeating another question, but I can't seem to get this to work. I have a standard java project in which I've written code to parse some BBC Radio XML data from the internet. The project is called BBCSchedules and the class I'm interested in is called BBCChannel. I'm now trying to use the BBCChannel class in an android application. How should I go about doing this? I've tried various things, following various bits of advice on the internet, and the place I've got to at the moment is compiling my BBCSchedules project to a .jar file, and importing that to the Android project using the Build Path/Library/Add External Jar option. However, Eclispe still doesn't recognise the BBCChannel class, and won't let me run the application because of this. I guess I've done something silly wrong, but what is it? Cheers, Robin UPDATE: I've tried the steps listed in http://stackoverflow.com/questions/1334802/how-can-i-use-external-jars-in-an-android-project and various other StackOverflow questions I can find that seem to be related to this, but absolutely nothing seems to work. Any other ideas? UPDATE: The discussions I've had with the author of the first answer below suggest that it is something to do with how I am using Eclipse to attach the .jar file. The project he sent me with the .jar file already attached didn't work. Any other ideas anyone?

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• How to improve Visual C++ compilation times?

  - by dtrosset

  I am compiling 2 C++ projects in a buildbot, on each commit. Both are around 1000 files, one is 100 kloc, the other 170 kloc. Compilation times are very different from gcc (4.4) to Visual C++ (2008). Visual C++ compilations for one project take in the 20 minutes. They cannot take advantage of the multiple cores because a project depend on the other. In the end, a full compilation of both projects in Debug and Release, in 32 and 64 bits takes more than 2 1/2 hours. gcc compilations for one project take in the 4 minutes. It can be parallelized on the 4 cores and takes around 1 min 10 secs. All 8 builds for 4 versions (Debug/Release, 32/64 bits) of the 2 projects are compiled in less than 10 minutes. What is happening with Visual C++ compilation times? They are basically 5 times slower. What is the average time that can be expected to compile a C++ kloc? Mine are 7 s/kloc with vc++ and 1.4 s/kloc with gcc. Can anything be done to speed-up compilation times on Visual C++?

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• GWT in its web-mode throws StatusCodeException but in its hosted-mode , it's working perfect

  - by broshni

  Hi to all, I am new to this forum. Actually I have an issue here regarding my application which is hibernate+struts based application. Recently we have decided to integrate GWT into our application. We are using gwt 1.5.3 build. We have set up everything exactly as we find in documentation and various blogs. Yeah I am now in a very nervy state as gwt in its web- mode is treating me in a very embarassing manner. But it is compiling and working perfectly fine in its hosted-mode and everything works fine as we expected and designed. When I try to integrate GWT with our application i.e. running in tomcat (http://localhost:8080/myapps/example.do? reqCode=takeMeToGWT&userId=12&templateId=10). The gwt page is loaded partially and in the midst it throws an exception i.e. StatusCodeException. This doesn't happen when I run the gwt application in hosted-mode ( http://localhost:8888/com.myapp.gwt.MyApp/Home.html ) . I am using Intellij Idea 8, struts 1.3 ,hibernate 3 and tomcat 5.5 . Expecting your responses at the earliest possible time. Thanking you B Roshnikanta Sharma [email protected]

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• Efficiency of manually written loops vs operator overloads (C++)

  - by Sagekilla

  Hi all, in the program I'm working on I have 3-element arrays, which I use as mathematical vectors for all intents and purposes. Through the course of writing my code, I was tempted to just roll my own Vector class with simple +, -, *, /, etc overloads so I can simplify statements like: for (int i = 0; i < 3; i++) r[i] = r1[i] - r2[i]; // becomes: r = r1 - r2; Which should be more or less identical in generated code. But when it comes to more complicated things, could this really impact my performance heavily? One example that I have in my code is this: Manually written version: for (int j = 0; j < 3; j++) { p.vel[j] = p.oldVel[j] + (p.oldAcc[j] + p.acc[j]) * dt2 + (p.oldJerk[j] - p.jerk[j]) * dt12; p.pos[j] = p.oldPos[j] + (p.oldVel[j] + p.vel[j]) * dt2 + (p.oldAcc[j] - p.acc[j]) * dt12; } Using a Vector class with operator overloads: p.vel = p.oldVel + (p.oldAcc + p.acc) * dt2 + (p.oldJerk - p.jerk) * dt12; p.pos = p.oldPos + (p.oldVel + p.vel) * dt2 + (p.oldAcc - p.acc) * dt12; I am compiling my code for maximum possible speed, as it's extremely important that this code runs quickly and calculates accurately. So will me relying on my Vector's for these sorts of things really affect me? For those curious, this is part of some numerical integration code which is not trivial to run in my program. Any insight would be appreciated, as would any idioms or tricks I'm unaware of.

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• Problems with variadic function

  - by morpheous

  I have the following function from some legacy code that I am maintaining. long getMaxStart(long start, long count, const myStruct *s1, ...) { long i1, maxstart; myStruct *s2; va_list marker; maxstart = start; /*BUGFIX: 003 */ /*(va_start(marker, count);*/ va_start(marker, s1); for (i1 = 1; i1 <= count; i1++) { s2 = va_arg(marker, myStruct *); /* <- s2 is assigned null here */ maxstart = MAX(maxstart, s2->firstvalid); /* <- SEGV here */ } va_end(marker); return (maxstart); } When the function is called with only one myStruct argument, it causes a SEGV. The code compiled and run without crashing on Windows XP when I compiled it using VS2005. I have now moved the code to Ubuntu Karmic and I am having problems with the stricter compiler on Linux. Is anyone able to spot what is causing the parameter not to be read correctly in the var_arg() statement? I am compiling using gcc version 4.4.1 Edit The statement that causes the SEGV is this one: start = getMaxStart(start, 1, ms1); The variables 'start' and 'ms1' have valid values when the code execution first reaches this line.

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• Enumeration trouble: redeclared as different kind of symbol

  - by Matt

  Hello all. I am writing a program that is supposed to help me learn about enumeration data types in C++. The current trouble is that the compiler doesn't like my enum usage when trying to use the new data type as I would other data types. I am getting the error "redeclared as different kind of symbol" when compiling my trangleShape function. Take a look at the relevant code. Any insight is appreciated! Thanks! (All functions are their own .cpp files.) header file #ifndef HEADER_H_INCLUDED #define HEADER_H_INCLUDED #include <iostream> #include <iomanip> using namespace std; enum triangleType {noTriangle, scalene, isoceles, equilateral}; //prototypes void extern input(float&, float&, float&); triangleType extern triangleShape(float, float, float); /*void extern output (float, float, float);*/ void extern myLabel(const char *, const char *); #endif // HEADER_H_INCLUDED main function //8.1 main // this progam... #include "header.h" int main() { float sideLength1, sideLength2, sideLength3; char response; do //main loop { input (sideLength1, sideLength2, sideLength3); triangleShape (sideLength1, sideLength2, sideLength3); //output (sideLength1, sideLength2, sideLength3); cout << "\nAny more triangles to analyze? (y,n) "; cin >> response; } while (response == 'Y' || response == 'y'); myLabel ("8.1", "2/11/2011"); return 0; } triangleShape shape # include "header.h" triangleType triangleShape(sideLenght1, sideLength2, sideLength3) { triangleType triangle; return triangle; }

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