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  • Bizarre C++ compiler problem

    - by Yassin
    Hi, I have the following C++ code: typedef istream_iterator<string> isi; // (1) vector<string> lineas(isi(cin), isi()); // (2) //vector<string> lineas; //copy(isi(cin), isi(), back_inserter(lineas)); typedef vector<string>::iterator vci; for (vci it = lineas.begin(); it != lineas.end(); ++it) cout &lt;&lt; *it &lt;&lt; endl; However, I get the error while compiling: test.cpp: In function 'int main(int, char**)': test.cpp:16: error: request for member 'begin' in 'lineas', which is of non-class type 'std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >(main(int, char**)::isi, main(int, char**)::isi (*)())' test.cpp:16: error: request for member 'end' in 'lineas', which is of non-class type 'std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > >(main(int, char**)::isi, main(int, char**)::isi (*)())' However, if I replace (1) by (2), it compiles. I'm using g++ 4.4.0 What's wrong?

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  • Cannot understand the behaviour of C# compiler while instantiating a class thru interface

    - by Newbie
    I have a class that implements an interface. The interface is public interface IRiskFactory { void StartService(); void StopService(); } The class that implements the interface is public class RiskFactoryService : IRiskFactory { } Now I have a console application and one window service. From the console application if I write the following code static void Main(string[] args) { IRiskFactory objIRiskFactory = new RiskFactoryService(); objIRiskFactory.StartService(); Console.ReadLine(); objIRiskFactory.StopService(); } It is working fine. However, when I mwrite the same piece of code in Window service public partial class RiskFactoryService : ServiceBase { IRiskFactory objIRiskFactory = null; public RiskFactoryService() { InitializeComponent(); objIRiskFactory = new RiskFactoryService(); <- ERROR } /// <summary> /// Starts the service /// </summary> /// <param name="args"></param> protected override void OnStart(string[] args) { objIRiskFactory.StartService(); } /// <summary> /// Stops the service /// </summary> protected override void OnStop() { objIRiskFactory.StopService(); } } It throws error: Cannot implicitly convert type 'RiskFactoryService' to 'IRiskFactory'. An explicit conversion exists (are you missing a cast?) When I type cast to the interface type, it started working objIRiskFactory = (IRiskFactory)new RiskFactoryService(); My question is why so?

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  • CString a = "Hello " + "World!"; Is it possible?

    - by Sanctus2099
    I'm making my own string class and I was wondering if there's any way to replace the compiler behaviour around " characters. As I said in the title I'd like to make it so that CString a = "Hello " + "World!"; would actually work and not give a compiler error telling that it can't add 2 pointers. My string class automatically converts to char* when needed and thus writing printf(a) would not break the code. I'm sure this is a rather weird question but if it's possible I'd really like to know how to do it. Thank you very much

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  • Is there a perfect algorithm for chess?

    - by Overflown
    Dear Stack Overflow community, I was recently in a discussion with a non-coder person on the possibilities of chess computers. I'm not well versed in theory, but think I know enough. I argued that there could not exist a deterministic Turing machine that always won or stalemated at chess. I think that, even if you search the entire space of all combinations of player1/2 moves, the single move that the computer decides upon at each step is based on a heuristic. Being based on a heuristic, it does not necessarily beat ALL of the moves that the opponent could do. My friend thought, to the contrary, that a computer would always win or tie if it never made a "mistake" move (however do you define that?). However, being a programmer who has taken CS, I know that even your good choices - given a wise opponent - can force you to make "mistake" moves in the end. Even if you know everything, your next move is greedy in matching a heuristic. Most chess computers try to match a possible end game to the game in progress, which is essentially a dynamic programming traceback. Again, the endgame in question is avoidable though. -- thanks, Allan Edit: Hmm... looks like I ruffled some feathers here. That's good. Thinking about it again, it seems like there is no theoretical problem with solving a finite game like chess. I would argue that chess is a bit more complicated than checkers in that a win is not necessarily by numerical exhaustion of pieces, but by a mate. My original assertion is probably wrong, but then again I think I've pointed out something that is not yet satisfactorily proven (formally). I guess my thought experiment was that whenever a branch in the tree is taken, then the algorithm (or memorized paths) must find a path to a mate (without getting mated) for any possible branch on the opponent moves. After the discussion, I will buy that given more memory than we can possibly dream of, all these paths could be found.

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  • Create My own language with "Functional Programming Language"

    - by esehara
    I prefer Haskell. I already know How to create my own language with Procedural Language (for example: C, Java, Python, etc). But, I know How to create my own language with Functional Language (for example Haskell, Clojure and Scala). I've already read: Internet Resources Write Yourself a Scheme in 48 Hours Real World Haskell - Chapter 16.Using Persec Writing A Lisp Interpreter In Haskell Parsec, a fast combinator parser Implementing functional languages: a tutorial Books Introduction Functional Programming Using Haskell 2nd Edition -- Haskell StackOverflow (but with procedural language) Learning to write a compiler create my own programming language Source Libraries and tools/HJS -- Haskell Are there any other good sources? I wants to get more links,or sources.

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  • Is there a term for this concept, and does it exist in a static-typed language?

    - by Strilanc
    Recently I started noticing a repetition in some of my code. Of course, once you notice a repetition, it becomes grating. Which is why I'm asking this question. The idea is this: sometimes you write different versions of the same class: a raw version, a locked version, a read-only facade version, etc. These are common things to do to a class, but the translations are highly mechanical. Surround all the methods with lock acquires/releases, etc. In a dynamic language, you could write a function which did this to an instance of a class (eg. iterate over all the functions, replacing them with a version which acquires/releases a lock.). I think a good term for what I mean is 'reflected class'. You create a transformation which takes a class, and returns a modified-in-a-desired-way class. Synchronization is the easiest case, but there are others: make a class immutable [wrap methods so they clone, mutate the clone, and include it in the result], make a class readonly [assuming you can identify mutating methods], make a class appear to work with type A instead of type B, etc. The important part is that, in theory, these transformations make sense at compile-time. Even though an ActorModel<T> has methods which change depending on T, they depend on T in a specific way knowable at compile-time (ActorModel<T> methods would return a future of the original result type). I'm just wondering if this has been implemented in a language, and what it's called.

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  • When to use CTEs to encapsulate sub-results, and when to let the RDBMS worry about massive joins.

    - by IanC
    This is a SQL theory question. I can provide an example, but I don't think it's needed to make my point. Anyone experienced with SQL will immediately know what I'm talking about. Usually we use joins to minimize the number of records due to matching the left and right rows. However, under certain conditions, joining tables cause a multiplication of results where the result is all permutations of the left and right records. I have a database which has 3 or 4 such joins. This turns what would be a few records into a multitude. My concern is that the tables will be large in production, so the number of these joined rows will be immense. Further, heavy math is performed on each row, and the idea of performing math on duplicate rows is enough to make anyone shudder. I have two questions. The first is, is this something I should care about, or will SQL Server intelligently realize these rows are all duplicates and optimize all processing accordingly? The second is, is there any advantage to grouping each part of the query so as to get only the distinct values going into the next part of the query, using something like: WITH t1 AS ( SELECT DISTINCT... [or GROUP BY] ), t2 AS ( SELECT DISTINCT... ), t3 AS ( SELECT DISTINCT... ) SELECT... I have often seen the use of DISTINCT applied to subqueries. There is obviously a reason for doing this. However, I'm talking about something a little different and perhaps more subtle and tricky.

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  • How do you install less css command line compiler?

    - by chrisjlee
    From my understanding and correct me if I'm wrong, I have to get ruby or NPM installed to get the less css compiler working. I don't have any ruby installed and I'm not really sure how to get my computer to that point. I also want to minimize my footprint; installing the minimal amount of ruby libraries if possible (because i will never use ruby except for when i run less). What are the steps involved in getting less working and running? Before you down vote, I know there was this previous thread (Less CCS compiler install). This particular person already has some other packages installed. I'm trying to figure out all the packages needed to get to that point. Or if someone could point me to the right documentation I would be thrilled!

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  • C++ behavior of for loops vs. while loops

    - by kjh
    As far as I understand, when you write a for-loop similar to this one for (int i = 0; i < SOME_NUM; i++) { if (true) do_something(); else do_something_else(); } The time complexity of this operation is mostly affected by the if (true) statement because the for-loop iterations don't actually involve any comparisons of i to SOME_NUM, the compiler will just essentially run the code inside the for-loop SOME_NUM times. Please correct me if I am wrong. However if this is correct, then how do the following nested for-loops behave? for (int i = 0; i < SOME_NUM; i++) { for (int j = 0; j < i; j++) { do_something(); } } The j in the inner for-loop is now upper bound by i, a value that changes every time the loop restarts. How will the compiler compile this? Do these nested for-loops essentially behave like a for-loop with while-loop inside of it? If you're writing an algorithm that uses nested for-loops where the inner counting variable depends on the outer counting variable should you be concerned about what this will do to the complexity of your algorithm?

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  • android compile error: could not reserve enough space for object heap

    - by moonlightcheese
    I'm getting this error during compilation: Error occurred during initialization of VM Could not create the Java virtual machine. Could not reserve enough space for object heap What's worse, the error occurs intermittently. Sometimes it happens, sometimes it doesn't. It seems to be dependent on the amount of code in the application. If I get rid of some variables or drop some imported libraries, it will compile. Then when I add more to it, I get the error again. I've included the following sources into the application in the [project_root]/src/ directory: org.apache.httpclient (I've stripped all references to log4j from the sources, so don't need it) org.apache.codec (as a dependency) org.apache.httpcore (dependency of httpclient) and my own activity code consisting of nothing more than an instance of HttpClient. I know this has something to do with the amount of memory necessary during compile time or some compiler options, and I'm not really stressing my system while i'm coding. I've got 2GB of memory on this Core Duo laptop and windows reports only 860MB page file usage (haven't used any other memory tools. I should have plenty of memory and processing power for this... and I'm only compiling some common http libs... total of 406 source files. What gives? edit (4/30/2010-18:24): Just compiled some code where I got the above stated error. I closed some web browser windows and recompiled the same exact code with no edits and it compiled with no issue. this is definitely a compiler issue related to memory usage. Any help would be great.... because I have no idea where to go from here. Android API Level: 5 Android SDK rel 5 JDK version: 1.6.0_12 Sorry I had to repost this question because regardless of whether I use the native HttpClient class in the Android SDK or my custom version downloaded from apache, the error still occurs.

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  • Exclude debug javascript code during minification

    - by Tauren
    I looking into different ways to minify my javascript code including the regular JSMin, Packer, and YUI solutions. I'm really interested in the new Google Closure Compiler, as it looks exceptionally powerful. I noticed that Dean Edwards packer has a feature to exclude lines of code that start with three semicolons. This is handy to exclude debug code. For instance: ;;; console.log("Starting process"); I'm spending some time cleaning up my codebase and would like to add hints like this to easily exclude debug code. In preparation for this, I'd like to figure out if this is the best solution, or if there are other techniques. Because I haven't chosen how to minify yet, I'd like to clean the code in a way that is compatible with whatever minifier I end up going with. So my questions are these: Is using the semicolons a standard technique, or are there other ways to do it? Is Packer the only solution that provides this feature? Can the other solutions be adapted to work this way as well, or do they have alternative ways of accomplishing this? I will probably start using Closure Compiler eventually. Is there anything I should do now that would prepare for it?

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  • VERY simple C program won't compile with VC 64

    - by Paperflyer
    Here is a very simple C program: #include <stdio.h> int main (int argc, char *argv[]) { printf("sizeof(short) = %d\n",(int)sizeof(short)); printf("sizeof(int) = %d\n",(int)sizeof(int)); printf("sizeof(long) = %d\n",(int)sizeof(long)); printf("sizeof(long long) = %d\n",(int)sizeof(long long)); printf("sizeof(float) = %d\n",(int)sizeof(float)); printf("sizeof(double) = %d\n",(int)sizeof(double)); return 0; } While it compiles fine on Win32 (command line: cl main.c), it does not using the Win64 compiler ("c:\Program Files(x86)\Microsoft Visual Studio 9.0\VC\bin\amd64\cl.exe" main.c). Specifically, it sais "error LNK2019: unresolved external symbol printf referenced in function main". As far as I understand this, it can not link to printf, right? Obviously, I have Microsoft Visual C++ Compiler 2008 (Standard enu) x86 and x64 installed and am using the 64-bit flavor of Windows (7). What is the problem here?

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  • Singleton with inheritance, Derived class is not able to get instantiated in parent?

    - by yesraaj
    Below code instantiates a derived singleton object based on environment variable. The compiler errors saying error C2512: 'Dotted' : no appropriate default constructor. I don't understand what the compiler is complaining about. #include <stdlib.h> #include <iostream> #include <string> using namespace std; class Dotted; class Singleton{ public: static Singleton instant(){ if (!instance_) { char * style = getenv("STYLE"); if (!style){ if (strcmp(style,"dotted")==0) { instance_ = new Dotted(); return *instance_; } } else{ instance_ = new Singleton(); return *instance_; } } return *instance_; } void print(){cout<<"Singleton";} ~Singleton(){}; protected: Singleton(){}; private: static Singleton * instance_; Singleton(const Singleton & ); void operator=(const Singleton & ); }; class Dotted:public Singleton{ public: void print(){cout<<"Dotted";} protected: Dotted(); }; Dotted::Dotted():Singleton(){} int main(){ Singleton::instant().print(); cin.get(); }

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  • Unable to create a breakpoint in Eclipse and Tomcat

    - by Traroth
    Since yesterday, I get a strange error message when I start my Tomcat (6.0.35) under Eclipse Juno (build 20120614-1722): Among the things I tried in order to get rid of the error: Check in Preferences - Java - Compiler if all "Classfile Generation" checkboxes where checked. I did that for both general preferences and project preference Uncheck them, build, check them build again (found on another question) Add org.eclipse.jdt.core.compiler.debug.lineNumber=generate to my .settings/org.eclipse.jdt.core.prefs file Use a new CVS checkout (same symptoms) And now, I don't know what to do anymore. The problem is really stopping me from get anything done. I can't work anymore. Crazy is: the problem doesn't happen on every class, only on some of them. Neither does it happen on my other Eclipse projects. And it didn't happen before yesterday, even if I can't remeber having done anything weird. Actually, I have never seen a problem like this in almost 10 years I'm using Eclipse... If you have any idea, I would be really grateful... Edit: I also tried to ignore the message and go on with my tests: If I create another breakpoint upstream from my problematic class, when I enter this problematic class, it tries to open a $Proxy132 class, which means it actually opens an empty page, with a source not found message

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  • No "redefinition of default parameter error" for class template member function?

    - by STingRaySC
    Why does the following give no compilation error?: // T.h template<class T> class X { public: void foo(int a = 42); }; // Main.cpp #include "T.h" #include <iostream> template<class T> void X<T>::foo(int a = 13) { std::cout << a << std::endl; } int main() { X<int> x; x.foo(); // prints 42 } It seems as though the 13 is just silently ignored by the compiler. Why is this? The cooky thing is that if the template declaration is in Main.cpp instead of a header file, I do indeed get the default parameter redefinition error. Now I know the compiler will complain about this if it were just an ordinary (non-template) function. What does the standard have to say about default parameters in class template member functions or function templates?

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  • Why is gcc failing with "unrecognized command line option "-L/lusr/opt/mpfr-2.4.2/lib" "?

    - by Mike
    My sysadmin recently installed a new version of GCC, in /lusr/opt/gcc-4.4.3. I tested it as follows: mike@canon:~$ cat test.c int main(){ return 0; } mike@canon:~$ gcc test.c /lusr/opt/gcc-4.4.3/libexec/gcc/i686-pc-linux-gnu/4.4.3/cc1: error while loading shared libraries: libmpfr.so.1: cannot open shared object file: No such file or directory After informing my sysadmin about this, he said to add /lusr/opt/mpfr-2.4.2/lib:/lusr/opt/gmp-4.3.2/lib to my LD_LIBRARY_PATH. After doing this, I get the following error: mike@canon:~$ gcc test.c cc1: error: unrecognized command line option "-L/lusr/opt/mpfr-2.4.2/lib" First, my sysadmin wasn't entirely sure this was the best workaround(though he did say it worked for him...), so is there a better solution? Second, why am I getting a linker error from cc, and how can I fix it? Some information which may be helpful: mike@canon:~$ env | grep mpfr OLDPWD=/lusr/opt/mpfr-2.4.2/lib LD_LIBRARY_PATH=/lusr/opt/mpfr-2.4.2/lib:/lusr/opt/gmp-4.3.2/lib: mike@canon:~$ echo $LDFLAGS (the above is a blank line)

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  • libstdc++ - compiling failing because of tr1/regex

    - by Radek Šimko
    I have these packages installed on my OpenSUSE 11.3: i | libstdc++45 | Standard shared library for C++ | package i | libstdc++45-devel | Contains files and libraries for development | package But when i'm trying to compile this C++ code: #include <stdio.h> #include <tr1/regex> using namespace std; int main() { int test[2]; const tr1::regex pattern(".*"); test[0] = 1; if (tr1::regex_match("anything", pattern) == false) { printf("Pattern does not match.\n"); } return 0; } using g++ -pedantic -g -O1 -o ./main.o ./main.cpp It outputs this errors: ./main.cpp: In function ‘int main()’: ./main.cpp:13:43: error: ‘printf’ was not declared in this scope radek@mypc:~> nano main.cpp radek@mypc:~> g++ -pedantic -g -O1 -o ./main.o ./main.cpp /tmp/cc0g3GUE.o: In function `basic_regex': /usr/include/c++/4.5/tr1_impl/regex:771: undefined reference to `std::tr1::basic_regex<char, std::tr1::regex_traits<char> >::_M_compile()' /tmp/cc0g3GUE.o: In function `bool std::tr1::regex_match<char const*, char, std::tr1::regex_traits<char> >(char const*, char const*, std::tr1::basic_regex<char, std::tr1::regex_traits<char> > const&, std::bitset<11u>)': /usr/include/c++/4.5/tr1_impl/regex:2144: undefined reference to `bool std::tr1::regex_match<char const*, std::allocator<std::tr1::sub_match<char const*> >, char, std::tr1::regex_traits<char> >(char const*, char const*, std::tr1::match_results<char const*, std::allocator<std::tr1::sub_match<char const*> > >&, std::tr1::basic_regex<char, std::tr1::regex_traits<char> > const&, std::bitset<11u>)' collect2: ld returned 1 exit status What packages should i (un)install to make the code work on my PC?

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  • Xeon X3220 Dual-Core 2.4 GHz - which march setting for gcc?

    - by hurikhan77
    Should I use -march=nocona or -march=core2 when compiling binaries for this processor with gcc 4.3? vendor_id : GenuineIntel cpu family : 6 model : 15 model name : Intel(R) Xeon(R) CPU X3220 @ 2.40GHz stepping : 8 cpuid level : 10 flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss syscall nx lm constant_tsc arch_perfmon pebs bts rep_good pni ssse3 cx16 lahf_lm I cannot really find if this CPU is already core2 architecture... Only find information about the quad core variants, but this CPU is only dual core.

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  • Maximum Method Name Length

    - by Josh
    Does anyone happen to know what the maximum length of a method name is in your programming language of choice? I was going to make this a C# specific question, but I think it would be nice to know across the spectrum. What are the factors involved as well: Does the language specification limit this? What does the compiler limit it to? Is it different on 32bit vs 64bit machines?

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  • using graphviz with qt

    - by radi
    hi , i have a compiler project and i want to print the ast after the compile complete so can i print this ast to qt (on c++) panel using graphviz ? note : i dont know if there is a binding between qt or c++ and graphviz , so if it doesnt work please help me to find the alternative . thanks .

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  • Xcode Objective-c warnings "creating selector for nonexistent method" with OCUnit (SenTestingKit)

    - by niblha
    I started getting getting warnings like the following in XCode when trying to write some unit tests with OCUnit (SenTestingKit). warning: creating selector for nonexistent method 'myMethodName1:' warning: creating selector for nonexistent method 'myMethodName2:' ... warning: creating selector for nonexistent method 'release' warning: creating selector for nonexistent method 'retain' warning: creating selector for nonexistent method 'alloc' warning: creating selector for nonexistent method 'init' Is it something I should worry about, or can I somehow disable these types of warnings by some compiler flag?

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  • What does `const` do when combined with `readonly`?

    - by Byron Sommardahl
    The difference between const and readonly is well covered. A const can't be changed and a read only can only be changed in a constructor. But, what happens when you combine the two: public readonly const string how_does_this_behave = "I don't know"; The compiler allows it. But I'm not sure how it behaves from this point on. Thoughts?

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  • Delphi 6 - Bugs disappear when I compile multiple times.

    - by Daisetsu
    My Delphi installation has been going downhill for the past few months. It seems though that every so often when I build a release it has strange errors in it which are resolved if I build, then compile, then build, compile, etc. I've talked to another developer who thinks that this is a compiler error. This sort of degrading performance over time has happened on other computers to us too. What does stack overflow think could be the problem.

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