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  • Coordinating typedefs and structs in std::multiset (C++)

    - by Sarah
    I'm not a professional programmer, so please don't hesitate to state the obvious. My goal is to use a std::multiset container (typedef EventMultiSet) called currentEvents to organize a list of structs, of type Event, and to have members of class Host occasionally add new Event structs to currentEvents. The structs are supposed to be sorted by one of their members, time. I am not sure how much of what I am trying to do is legal; the g++ compiler reports (in "Host.h") "error: 'EventMultiSet' has not been declared." Here's what I'm doing: // Event.h struct Event { public: bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } double time; int eventID; int hostID; }; // Host.h ... void calcLifeHist( double, EventMultiSet * ); // produces compiler error ... void addEvent( double, int, int, EventMultiSet * ); // produces compiler error // Host.cpp #include "Event.h" ... // main.cpp #include "Event.h" ... typedef std::multiset< Event, std::less< Event > > EventMultiSet; EventMultiSet currentEvents; EventMultiSet * cePtr = &currentEvents; ... Major questions Where should I include the EventMultiSet typedef? Are my EventMultiSet pointers obviously problematic? Is the compare function within my Event struct (in theory) okay? Thank you very much in advance.

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  • Simplest way to mix sequences of types with iostreams?

    - by Kylotan
    I have a function void write<typename T>(const T&) which is implemented in terms of writing the T object to an ostream, and a matching function T read<typename T>() that reads a T from an istream. I am basically using iostreams as a plain text serialisation format, which obviously works fine for most built-in types, although I'm not sure how to effectively handle std::strings just yet. I'd like to be able to write out a sequence of objects too, eg void write<typename T>(const std::vector<T>&) or an iterator based equivalent (although in practice, it would always be used with a vector). However, while writing an overload that iterates over the elements and writes them out is easy enough to do, this doesn't add enough information to allow the matching read operation to know how each element is delimited, which is essentially the same problem that I have with a single std::string. Is there a single approach that can work for all basic types and std::string? Or perhaps I can get away with 2 overloads, one for numerical types, and one for strings? (Either using different delimiters or the string using a delimiter escaping mechanism, perhaps.)

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  • How to store a linked list in a struct in C

    - by LuckySlevin
    typedef struct child_list {int count; char vo[100]; child_list*next;} child_list; typedef struct parent_list { char vo[100]; child_list * head; int count; parent_list * next; } parent_list; As you can see there are two structures. child_list is used to create a linked list. And this list will be stored in a linked list of parent list. My problem is to display the child list which in the parent_list. My desire to get while displaying the linked list of parent_list: This lists work with this logic. I already made append and other stuff. For example if i enter ab cd ab ja cd ab Word Count List ab 3 cd->ja cd 2 ab->ab ja 1 cd The problematic part is displaying child_list which is in the parent_list nodes(List column of output). I don't know my question is clear please ask for further info.

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  • Suggestions for a django db structure

    - by rh0dium
    Hi Say I have the unknown number of questions. For example: Is the sky blue [y/n] What date were your born on [date] What is pi [3.14] What is a large integ [100] Now each of these questions poses a different but very type specific answer (boolean, date, float, int). Natively django can happily deal with these in a model. class SkyModel(models.Model): question = models.CharField("Is the sky blue") answer = models.BooleanField(default=False) class BirthModel(models.Model): question = models.CharField("What date were your born on") answer = models.DateTimeField(default=today) class PiModel(models.Model) question = models.CharField("What is pi") answer = models.FloatField() But this has the obvious problem in that each question has a specific model - so if we need to add a question later I have to change the database. Yuck. So now I want to get fancy - How do a set up a model where by the answer type conversion happens automagically? ANSWER_TYPES = ( ('boolean', 'boolean'), ('date', 'date'), ('float', 'float'), ('int', 'int'), ('char', 'char'), ) class Questions(models.model): question = models.CharField(() answer = models.CharField() answer_type = models.CharField(choices = ANSWER_TYPES) default = models.CharField() So in theory this would do the following: When I build up my views I look at the type of answer and ensure that I only put in that value. But when I want to pull that answer back out it will return the data in the format specified by the answer_type. Example 3.14 comes back out as a float not as a str. How can I perform this sort of automagic transformation? Or can someone suggest a better way to do this? Thanks much!!

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  • How do I prevent qFatal() from aborting the application?

    - by Dave
    My Qt application uses Q_ASSERT_X, which calls qFatal(), which (by default) aborts the application. That's great for the application, but I'd like to suppress that behavior when unit testing the application. (I'm using the Google Test Framework.) I have by unit tests in a separate project, statically linking to the class I'm testing. The documentation for qFatal() reads: Calls the message handler with the fatal message msg. If no message handler has been installed, the message is printed to stderr. Under Windows, the message is sent to the debugger. If you are using the default message handler this function will abort on Unix systems to create a core dump. On Windows, for debug builds, this function will report a _CRT_ERROR enabling you to connect a debugger to the application. ... To supress the output at runtime, install your own message handler with qInstallMsgHandler(). So here's my main.cpp file: #include <gtest/gtest.h> #include <QApplication> void testMessageOutput(QtMsgType type, const char *msg) { switch (type) { case QtDebugMsg: fprintf(stderr, "Debug: %s\n", msg); break; case QtWarningMsg: fprintf(stderr, "Warning: %s\n", msg); break; case QtCriticalMsg: fprintf(stderr, "Critical: %s\n", msg); break; case QtFatalMsg: fprintf(stderr, "My Fatal: %s\n", msg); break; } } int main(int argc, char **argv) { qInstallMsgHandler(testMessageOutput); testing::InitGoogleTest(&argc, argv); return RUN_ALL_TESTS(); } But my application is still stopping at the assert. I can tell that my custom handler is being called, because the output when running my tests is: My Fatal: ASSERT failure in MyClass::doSomething: "doSomething()", file myclass.cpp, line 21 The program has unexpectedly finished. What can I do so that my tests keep running even when an assert fails?

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  • C to Assembly code - what does it mean

    - by Smith
    I'm trying to figure out exactly what is going on with the following assembly code. Can someone go down line by line and explain what is happening? I input what I think is happening (see comments) but need clarification. .file "testcalc.c" .section .rodata.str1.1,"aMS",@progbits,1 .LC0: .string "x=%d, y=%d, z=%d, result=%d\n" .text .globl main .type main, @function main: leal 4(%esp), %ecx // establish stack frame andl $-16, %esp // decrement %esp by 16, align stack pushl -4(%ecx) // push original stack pointer pushl %ebp // save base pointer movl %esp, %ebp // establish stack frame pushl %ecx // save to ecx subl $36, %esp // alloc 36 bytes for local vars movl $11, 8(%esp) // store 11 in z movl $6, 4(%esp) // store 6 in y movl $2, (%esp) // store 2 in x call calc // function call to calc movl %eax, 20(%esp) // %esp + 20 into %eax movl $11, 16(%esp) // WHAT movl $6, 12(%esp) // WHAT movl $2, 8(%esp) // WHAT movl $.LC0, 4(%esp) // WHAT?!?! movl $1, (%esp) // move result into address of %esp call __printf_chk // call printf function addl $36, %esp // WHAT? popl %ecx popl %ebp leal -4(%ecx), %esp ret .size main, .-main .ident "GCC: (Ubuntu 4.3.3-5ubuntu4) 4.3.3" .section .note.GNU-stack,"",@progbits Original code: #include <stdio.h> int calc(int x, int y, int z); int main() { int x = 2; int y = 6; int z = 11; int result; result = calc(x,y,z); printf("x=%d, y=%d, z=%d, result=%d\n",x,y,z,result); }

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  • CreateProcess() fails with an access violation

    - by John Doe
    My aim is to execute an external executable in my program. First, I used system() function, but I don't want the console to be seen to the user. So, I searched a bit, and found CreateProcess() function. However, when I try to pass a parameter to it, I don't know why, it fails. I took this code from MSDN, and changed a bit: #include <windows.h> #include <stdio.h> #include <tchar.h> void _tmain( int argc, TCHAR *argv[] ) { STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); ZeroMemory( &pi, sizeof(pi) ); /* if( argc != 2 ) { printf("Usage: %s [cmdline]\n", argv[0]); return; } */ // Start the child process. if( !CreateProcess( NULL, // No module name (use command line) L"c:\\users\\e\\desktop\\mspaint.exe", // Command line NULL, // Process handle not inheritable NULL, // Thread handle not inheritable FALSE, // Set handle inheritance to FALSE 0, // No creation flags NULL, // Use parent's environment block NULL, // Use parent's starting directory &si, // Pointer to STARTUPINFO structure &pi ) // Pointer to PROCESS_INFORMATION structure ) { printf( "CreateProcess failed (%d).\n", GetLastError() ); return; } // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); // Close process and thread handles. CloseHandle( pi.hProcess ); CloseHandle( pi.hThread ); } However, this code crated access violation somehow. Can I execute mspaint without showing user the console? Thank you very much.

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  • What are the default return values for operator< and operator[] in C++ (Visual Studio 6)?

    - by DustOff
    I've inherited a large Visual Studio 6 C++ project that needs to be translated for VS2005. Some of the classes defined operator< and operator[], but don't specify return types in the declarations. VS6 allows this, but not VS2005. I am aware that the C standard specifies that the default return type for normal functions is int, and I assumed VS6 might have been following that, but would this apply to C++ operators as well? Or could VS6 figure out the return type on its own? For example, the code defines a custom string class like this: class String { char arr[16]; public: operator<(const String& other) { return something1 < something2; } operator[](int index) { return arr[index]; } }; Would VS6 have simply put the return types for both as int, or would it have been smart enough to figure out that operator[] should return a char and operator< should return a bool (and not convert both results to int all the time)? Of course I have to add return types to make this code VS2005 C++ compliant, but I want to make sure to specify the same type as before, as to not immediately change program behavior (we're going for compatibility at the moment; we'll standardize things later).

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  • C: socket connection timeout

    - by The.Anti.9
    I have a simple program to check if a port is open, but I want to shorten the timeout length on the socket connection because the default is far too long. I'm not sure how to do this though. Here's the code: #include <sys/socket.h> #include <sys/time.h> #include <sys/types.h> #include <arpa/inet.h> #include <netinet/in.h> #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <netdb.h> #include <stdlib.h> #include <string.h> #include <unistd.h> int main(int argc, char **argv) { u_short port; /* user specified port number */ char addr[1023]; /* will be a copy of the address entered by u */ struct sockaddr_in address; /* the libc network address data structure */ short int sock = -1; /* file descriptor for the network socket */ if (argc != 3) { fprintf(stderr, "Usage %s <port_num> <address>", argv[0]); return EXIT_FAILURE; } address.sin_addr.s_addr = inet_addr(argv[2]); /* assign the address */ address.sin_port = htons(atoi(argv[2])); /* translate int2port num */ sock = socket(AF_INET, SOCK_STREAM, 0); if (connect(sock,(struct sockaddr *)&address,sizeof(address)) == 0) { printf("%i is open\n", port); } close(sock); return 0; }

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  • memcmp,strcmp,strncmp in C

    - by el10780
    I wrote this small piece of code in C to test memcmp() strncmp() strcmp() functions in C. Here is the code that I wrote: #include <stdio.h> #include <stdlib.h> #include <string.h> int main(int argc, char** argv) { char *word1="apple",*word2="atoms"; if (strncmp(word1,word2,5)==0) printf("strncmp result.\n"); if (memcmp(word1,word2,5)==0) printf("memcmp result.\n"); if (strcmp(word1,word2)==0) printf("strcmp result.\n"); } Can somebody explain me the differences because I am confused with these three functions?My main problem is that I have a file in which I tokenize its line of it,the problem is that when I tokenize the word "atoms" in the file I have to stop the process of tokenizing.I first tried strcmp() but unfortunately when it reached to the point where the word "atoms" were placed in the file it didn't stop and it continued,but when I used either the memcmp() or the strncmp() it stopped and I was happy.But then I thought,what if there will be a case in which there is one string in which the first 5 letters are a,t,o,m,s and these are being followed by other letters.Unfortunately,my thoughts were right as I tested it using the above code by initializing word1 to "atomsaaaaa" and word2 to atoms and memcmp() and strncmp() in the if statements returned 0.On the other hand strcmp() it didn't.It seems that I must use strcmp(). I have done google searches but I got more confused as I have seen sites and other forums to define these three differently.If it is possible for someone to give me correct explanations/definitions so I can use them correctly in my source code,I would be really grateful.

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  • C/C++ I18N mbstowcs question

    - by bogertron
    I am working on internationalizing the input for a C/C++ application. I have currently hit an issue with converting from a multi-byte string to wide character string. The code needs to be cross platform compatible, so I am using mbstowcs and wcstombs as much as possible. I am currently working on a WIN32 machine and I have set the locale to a non-english locale (Japanese). When I attempt to convert a multibyte character string, I seem to be having some conversion issues. Here is an example of the code: int main(int argc, char** argv) { wchar_t *wcsVal = NULL; char *mbsVal = NULL; /* Get the current code page, in my case 932, runs only on windows */ TCHAR szCodePage[10]; int cch= GetLocaleInfo( GetSystemDefaultLCID(), LOCALE_IDEFAULTANSICODEPAGE, szCodePage, sizeof(szCodePage)); /* verify locale is set */ if (setlocale(LC_CTYPE, "") == 0) { fprintf(stderr, "Failed to set locale\n"); return 1; } mbsVal = argv[1]; /* validate multibyte string and convert to wide character */ int size = mbstowcs(NULL, mbsVal, 0); if (size == -1) { printf("Invalid multibyte\n"); return 1; } wcsVal = (wchar_t*) malloc(sizeof(wchar_t) * (size + 1)); if (wcsVal == NULL) { printf("memory issue \n"); return 1; } mbstowcs(wcsVal, szVal, size + 1); wprintf(L"%ls \n", wcsVal); return 0; } At the end of execution, the wide character string does not contain the converted data. I believe that there is an issue with the code page settings, because when i use MultiByteToWideChar and have the current code page sent in EX: MultiByteToWideChar( CP_ACP, 0, mbsVal, -1, wcsVal, size + 1 ); in place of the mbstowcs calls, the conversion succeeds. My question is, how do I use the generic mbstowcs call instead of teh MuliByteToWideChar call?

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  • parse string with regular exression

    - by llamerr
    I trying to parse this string: $right = '34601)S(1,6)[2] - 34601)(11)[2] + 34601)(3)[2,4]'; with following regexp: const word = '(\d{3}\d{2}\)S{0,1}\([^\)]*\)S{0,1}\[[^\]]*\])'; preg_match('/'.word.'{1}(?:\s{1}([+-]{1})\s{1}'.word.'){0,}/', $right, $matches); print_r($matches); i want to return array like this: Array ( [0] => 34601)S(1,6)[2] - 34601)(11)[2] + 34601)(3)[2,4] [1] => 34601)S(1,6)[2] [2] => - [3] => 34601)(11)[2] [4] => + [5] => 34601)(3)[2,4] ) but i return only following: Array ( [0] => 34601)S(1,6)[2] - 34601)(11)[2] + 34601)(3)[2,4] [1] => 34601)S(1,6)[2] [2] => + [3] => 34601)(3)[2,4] ) i think, its becouse of [^)]* or [^]]* in the word, but how i should correct regexp for matching this in another way? i tryied to specify it: \d+(?:[,#]\d+){0,} so word become const word = '(\d{3}\d{2}\)S{0,1}\(\d+(?:[,#]\d+){0,}\)S{0,1}\[\d+(?:[,#]\d+){0,}\])'; but it gives nothing

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  • What is the rationale to not allow overloading of C++ conversions operator with non-member function

    - by Vicente Botet Escriba
    C++0x has added explicit conversion operators, but they must always be defined as members of the Source class. The same applies to the assignment operator, it must be defined on the Target class. When the Source and Target classes of the needed conversion are independent of each other, neither the Source can define a conversion operator, neither the Target can define a constructor from a Source. Usually we get it by defining a specific function such as Target ConvertToTarget(Source& v); If C++0x allowed to overload conversion operator by non member functions we could for example define the conversion implicitly or explicitly between unrelated types. template < typename To, typename From > operator To(const From& val); For example we could specialize the conversion from chrono::time_point to posix_time::ptime as follows template < class Clock, class Duration> operator boost::posix_time::ptime( const boost::chrono::time_point<Clock, Duration>& from) { using namespace boost; typedef chrono::time_point<Clock, Duration> time_point_t; typedef chrono::nanoseconds duration_t; typedef duration_t::rep rep_t; rep_t d = chrono::duration_cast<duration_t>( from.time_since_epoch()).count(); rep_t sec = d/1000000000; rep_t nsec = d%1000000000; return posix_time::from_time_t(0)+ posix_time::seconds(static_cast<long>(sec))+ posix_time::nanoseconds(nsec); } And use the conversion as any other conversion. For a more complete description of the problem, see here or on my Boost.Conversion library.. So the question is: What is the rationale to non allow overloading of C++ conversions operator with non-member functions?

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  • Currently using View, Should I use a hard table instead?

    - by 1001010101
    I am currently debating whether my table, mapping_uGroups_uProducts, which is a view formed by the following table: CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `db`.`mapping_uGroups_uProducts` AS select distinct `X`.`upID` AS `upID`,`Z`.`ugID` AS `ugID` from ((`db`.`mapping_uProducts_Products` `X` join `db`.`productsInfo` `Y` on((`X`.`pID` = `Y`.`pID`))) join `db`.`mapping_uGroups_Groups` `Z` on((`Y`.`gID` = `Z`.`gID`))); My current query is: SELECT upID FROM uProductsInfo \ JOIN fs_uProducts USING (upID) column \ JOIN mapping_uGroups_uProducts USING (upID) -- could be faster if we use hard table and index \ JOIN mapping_fs_key USING (fsKeyID) \ WHERE fsName="OVERALL" \ AND ugID=1 \ ORDER BY score DESC \ LIMIT 0,30; which is pretty slow. (for 30 results, it requires about 10 secondes). I think the reason for my query being so slow is definitely due to the fact that that particular query relies on a VIEW which has no index to speed things up. +----+-------------+----------------+--------+----------------+---------+---------+---------------------------------------+-------+---------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------------+--------+----------------+---------+---------+---------------------------------------+-------+---------------------------------+ | 1 | PRIMARY | mapping_fs_key | const | PRIMARY,fsName | fsName | 386 | const | 1 | Using temporary; Using filesort | | 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 19706 | Using where | | 1 | PRIMARY | uProductsInfo | eq_ref | PRIMARY | PRIMARY | 4 | mapping_uGroups_uProducts.upID | 1 | Using index | | 1 | PRIMARY | fs_uProducts | ref | upID | upID | 4 | db.uProductsInfo.upID | 221 | Using where | | 2 | DERIVED | X | ALL | PRIMARY | NULL | NULL | NULL | 40772 | Using temporary | | 2 | DERIVED | Y | eq_ref | PRIMARY | PRIMARY | 4 | db.X.pID | 1 | Distinct | | 2 | DERIVED | Z | ref | PRIMARY | PRIMARY | 4 | db.Y.gID | 2 | Using index; Distinct | +----+-------------+----------------+--------+----------------+---------+---------+---------------------------------------+-------+---------------------------------+ 7 rows in set (0.48 sec) The explain here looks pretty cryptic, and I don't know whether I should drop view and write a script to just insert everything in the view to a hard table. ( obviously, it will lose the flexibility of the view since the mapping changes quite frequently). Does anyone have any idea to how I can optimize my schema better?

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  • Eliminate full table scan due to BETWEEN (and GROUP BY)

    - by Dave Jarvis
    Description According to the explain command, there is a range that is causing a query to perform a full table scan (160k rows). How do I keep the range condition and reduce the scanning? I expect the culprit to be: Y.YEAR BETWEEN 1900 AND 2009 AND Code Here is the code that has the range condition (the STATION_DISTRICT is likely superfluous). SELECT COUNT(1) as MEASUREMENTS, AVG(D.AMOUNT) as AMOUNT, Y.YEAR as YEAR, MAKEDATE(Y.YEAR,1) as AMOUNT_DATE FROM CITY C, STATION S, STATION_DISTRICT SD, YEAR_REF Y FORCE INDEX(YEAR_IDX), MONTH_REF M, DAILY D WHERE -- For a specific city ... -- C.ID = 10663 AND -- Find all the stations within a specific unit radius ... -- 6371.009 * SQRT( POW(RADIANS(C.LATITUDE_DECIMAL - S.LATITUDE_DECIMAL), 2) + (COS(RADIANS(C.LATITUDE_DECIMAL + S.LATITUDE_DECIMAL) / 2) * POW(RADIANS(C.LONGITUDE_DECIMAL - S.LONGITUDE_DECIMAL), 2)) ) <= 50 AND -- Get the station district identification for the matching station. -- S.STATION_DISTRICT_ID = SD.ID AND -- Gather all known years for that station ... -- Y.STATION_DISTRICT_ID = SD.ID AND -- The data before 1900 is shaky; insufficient after 2009. -- Y.YEAR BETWEEN 1900 AND 2009 AND -- Filtered by all known months ... -- M.YEAR_REF_ID = Y.ID AND -- Whittled down by category ... -- M.CATEGORY_ID = '003' AND -- Into the valid daily climate data. -- M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR Update The SQL is performing a full table scan, which results in MySQL performing a "copy to tmp table", as shown here: +----+-------------+-------+--------+-----------------------------------+--------------+---------+-------------------------------+--------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+-----------------------------------+--------------+---------+-------------------------------+--------+-------------+ | 1 | SIMPLE | C | const | PRIMARY | PRIMARY | 4 | const | 1 | | | 1 | SIMPLE | Y | range | YEAR_IDX | YEAR_IDX | 4 | NULL | 160422 | Using where | | 1 | SIMPLE | SD | eq_ref | PRIMARY | PRIMARY | 4 | climate.Y.STATION_DISTRICT_ID | 1 | Using index | | 1 | SIMPLE | S | eq_ref | PRIMARY | PRIMARY | 4 | climate.SD.ID | 1 | Using where | | 1 | SIMPLE | M | ref | PRIMARY,YEAR_REF_IDX,CATEGORY_IDX | YEAR_REF_IDX | 8 | climate.Y.ID | 54 | Using where | | 1 | SIMPLE | D | ref | INDEX | INDEX | 8 | climate.M.ID | 11 | Using where | +----+-------------+-------+--------+-----------------------------------+--------------+---------+-------------------------------+--------+-------------+ Related http://dev.mysql.com/doc/refman/5.0/en/how-to-avoid-table-scan.html http://dev.mysql.com/doc/refman/5.0/en/where-optimizations.html http://stackoverflow.com/questions/557425/optimize-sql-that-uses-between-clause Thank you!

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  • Template trick to optimize out allocations

    - by anon
    I have: struct DoubleVec { std::vector<double> data; }; DoubleVec operator+(const DoubleVec& lhs, const DoubleVec& rhs) { DoubleVec ans(lhs.size()); for(int i = 0; i < lhs.size(); ++i) { ans[i] = lhs[i]] + rhs[i]; // assume lhs.size() == rhs.size() } return ans; } DoubleVec someFunc(DoubleVec a, DoubleVec b, DoubleVec c, DoubleVec d) { DoubleVec ans = a + b + c + d; } Now, in the above, the "a + b + c + d" will cause the creation of 3 temporary DoubleVec's -- is there a way to optimize this away with some type of template magic ... i.e. to optimize it down to something equivalent to: DoubleVec ans(a.size()); for(int i = 0; i < ans.size(); i++) ans[i] = a[i] + b[i] + c[i] + d[i]; You can assume all DoubleVec's have the same # of elements. The high level idea is to have do some type of templateied magic on "+", which "delays the computation" until the =, at which point it looks into itself, goes hmm ... I'm just adding thes numbers, and syntheizes a[i] + b[i] + c[i] + d[i] ... instead of all the temporaries. Thanks!

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  • creating QT gui using a thread in c++?

    - by rashid
    I am trying to create this QT gui using a thread but no luck. Below is my code. Problem is gui never shows up. /*INCLUDES HERE... .... */ using namespace std; struct mainStruct { int s_argc;<br> char ** s_argv; }; typedef struct mainStruct mas; void *guifunc(void * arg); int main(int argc, char * argv[]) { mas m;<br> m.s_argc = argc;<br> m.s_argv = argv;<br> pthread_t threadGUI; //start a new thread for gui int result = pthread_create(&threadGUI, NULL, guifunc, (void *) &m); if (result) {<br> printf("Error creating gui thread"); exit(0); } return 0; } void *guifunc(void * arg) { mas m = *(mas *)arg; QApplication app(m.s_argc,m.s_argv); //object instantiation<br> guiClass *gui = new guiClass(); //show gui<br> gui->show(); app.exec(); <br> }

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  • Segmentation fault on certain inputs and not others

    - by Brandon Schwandt
    Heres a function I wrote that has some debugging elements in it already. When i enter either a "y" or a "Y" as the input I get a segmentation fault during runtime. When I enter any other value the code runs. The seg fault kicks out after it scans and gives me the response but before the "scan worked" line is output. DOn't know why it would act like this only on these values. If anyone needs the function call I have that as well. query_user(char *response [10]) { printf("response after query call before clear=%s\n",response); strcpy(response,""); printf("response after clearing before scan=%s\n",response); printf("Enter another person into the line? y or n\n"); scanf("%s", response); printf("response after scan=%s\n",response); printf("scan worked"); } main() { char response [10]; strcpy(response,"y"); printf("response=%s\n",response); printf("When finished with program type \"done\" to exit\n"); while (strcmp(response,"done") != 0) { printf("response after while loop and before query call=%s\n",response); query_user(&response); } } output on error: response after query call before clear=y response after clearing before scan= Enter another person into the line? y or n y response after scan=y Segmentation Fault (core dumped) output on non-error: response after query call before clear=y response after clearing before scan= Enter another person into the line? y or n n response after scan=n scan worked Cycle number 0 (program continues to run outside this function)

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  • Capabilities & Linux & Java

    - by Marek Jelen
    Hi, I am experimenting with linux capabilities for java application ... I do not want to add capabilities to interpreter (JVM), so I tried to write simple wrapper (with debugging information printed to stdout): #include <stdio.h> #include <stdlib.h> #include <sys/capability.h> #include <unistd.h> int main(int argc, char *argv[]){ cap_t cap = cap_get_proc(); if (!cap) { perror("cap_get_proc"); exit(1); } printf("%s: running with caps %s\n", argv[0], cap_to_text(cap, NULL)); return execlp("/usr/bin/java", "-server", "-jar", "project.jar", (char *)NULL); } This way, I can se that the capability is set for this execucatable: ./runner: running with caps = cap_net_bind_service+p And getcap shows runner = cap_net_bind_service+ip I have the capability set to be inheritable, so there should be no problem. However java still don't want to bind to privileged ports :-( I am getting this error: sun/nio/ch/Net.java:-2:in `bind': java.net.SocketException: Permission denied (NativeException) Can someone help me to resolve this? Thanks in advance

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  • Saving ntext data from SQL Server to file directory using asp

    - by April
    A variety of files (pdf, images, etc.) are stored in a ntext field on a MS SQL Server. I am not sure what type is in this field, other than it shows question marks and undefined characters, I am assuming they are binary type. The script is supposed to iterate through the rows and extract and save these files to a temp directory. "filename" and "contenttype" are given, and "data" is whatever is in the ntext field. I have tried several solutions: 1) data.SaveToFile "/temp/"&filename, 2 Error: Object required: '????????????????????' ??? 2) File.WriteAllBytes "/temp/"&filename, data Error: Object required: 'File' I have no idea how to import this, or the Server for MapPath. (Cue: what a noob!) 3) Const adTypeBinary = 1 Const adSaveCreateOverWrite = 2 Dim BinaryStream Set BinaryStream = CreateObject("ADODB.Stream") BinaryStream.Type = adTypeBinary BinaryStream.Open BinaryStream.Write data BinaryStream.SaveToFile "C:\temp\" & filename, adSaveCreateOverWrite Error: Arguments are of the wrong type, are out of acceptable range, or are in conflict with one another. 4) Response.ContentType = contenttype Response.AddHeader "content-disposition","attachment;" & filename Response.BinaryWrite data response.end This works, but the file should be saving to the server instead of popping up save-as dialog. I am not sure if there is a way to save the response to file. Thanks for shedding light on any of these problems!

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  • Query about running a program through valgrind and getting false results comparing to other systems.

    - by FILIaS
    Yesterday i posted this: What's the problem with this code? [hashtable in C] and paxdiablo offered to help me. He posted a sample of code and asked me to run it through valgrind on my machine. This code normally generates: 12,4 But on my machine, i get 24,8. The doubled! I'm just curious why is that happening. Hope sb has a good explaination. I post also paxdiablo's code (for anyone who cant find it.) #include <stdio.h> #include <stdlib.h> typedef struct HashTable { int size ; struct List *head; struct List *tail; } HashTable; typedef struct List { char *number; char *name; int time; struct List *next; } List; #define size_of_table 211 HashTable *createHashTable(void) { HashTable *new_table = malloc(sizeof(*new_table)*size_of_table); //line 606 printf ("%d\n", sizeof(*new_table)); printf ("%d\n", sizeof(new_table)); if (new_table == NULL) { return NULL; } int i=0; for(i; i<size_of_table; i++) { new_table[i].size=0; new_table[i].head=NULL; new_table[i].tail=NULL; } return new_table; } int main(void) { HashTable *x = createHashTable(); free (x); return 0; }

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  • Multithreaded linked list traversal

    - by Rob Bryce
    Given a (doubly) linked list of objects (C++), I have an operation that I would like multithread, to perform on each object. The cost of the operation is not uniform for each object. The linked list is the preferred storage for this set of objects for a variety of reasons. The 1st element in each object is the pointer to the next object; the 2nd element is the previous object in the list. I have solved the problem by building an array of nodes, and applying OpenMP. This gave decent performance. I then switched to my own threading routines (based off Windows primitives) and by using InterlockedIncrement() (acting on the index into the array), I can achieve higher overall CPU utilization and faster through-put. Essentially, the threads work by "leap-frog'ing" along the elements. My next approach to optimization is to try to eliminate creating/reusing the array of elements in my linked list. However, I'd like to continue with this "leap-frog" approach and somehow use some nonexistent routine that could be called "InterlockedCompareDereference" - to atomically compare against NULL (end of list) and conditionally dereference & store, returning the dereferenced value. I don't think InterlockedCompareExchangePointer() will work since I cannot atomically dereference the pointer and call this Interlocked() method. I've done some reading and others are suggesting critical sections or spin-locks. Critical sections seem heavy-weight here. I'm tempted to try spin-locks but I thought I'd first pose the question here and ask what other people are doing. I'm not convinced that the InterlockedCompareExchangePointer() method itself could be used like a spin-lock. Then one also has to consider acquire/release/fence semantics... Ideas? Thanks!

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  • C++ trouble with pointers to objects

    - by Zibd
    I have a class with a vector of pointers to objects. I've introduced some elements on this vector, and on my main file I've managed to print them and add others with no problems. Now I'm trying to remove an element from that vector and check to see if it's not NULL but it is not working. I'm filling it with on class Test: Other *a = new Other(1,1); Other *b = new Other(2,2); Other *c = new Other(3,3); v->push_back(a); v->push_back(b); v->push_back(c); And on my main file I have: Test t; (...) Other *pointer = t.vect->at(0); delete t.vect->at(0); t.vect->erase(t.vect->begin()); if (pointer == NULL) { cout << "Nothing here.."; } // Never enters here..

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  • add uchar values in ushort array with sse2 or sse3

    - by pompolus
    i have an unsigned short dst[16][16] matrix and a larger unsigned char src[m][n] matrix. Now i have to access in the src matrix and add a 16x16 submatrix to dst, using sse2 or ss3. In a my older implementation, I was sure that my summed values ??were never greater than 256, so i could do this: for (int row = 0; row < 16; ++row) { __m128i subMat = _mm_lddqu_si128(reinterpret_cast<const __m128i*>(src)); dst[row] = _mm_add_epi8(dst[row], subMat); src += W; // Step to next row i need to add } where W is an offset to reach the desired rows. This code works, but now my values in src are larger and summed could be greater than 256, so i need to store them as ushort. i've tried this: for (int row = 0; row < 16; ++row) { __m128i subMat = _mm_lddqu_si128(reinterpret_cast<const __m128i*>(src)); dst[row] = _mm_add_epi16(dst[row], subMat); src += W; // Step to next row i need to add } but it doesn't work. I'm not so good with sse, so any help will be appreciated.

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  • creating a QT gui using a thread in c++?

    - by rashid
    I am trying to create this QT gui using a thread but no luck. Below is my code. Problem is gui never shows up. But if i put QApplication app(m.s_argc,m.s_argv); //object instantiation guiClass *gui = new guiClass(); //show gui gui-show(); app.exec(); in main() then it works. /*INCLUDES HERE... .... */ using namespace std; struct mainStruct { int s_argc; char ** s_argv; }; typedef struct mainStruct mas; void *guifunc(void * arg); int main(int argc, char * argv[]) { mas m; m.s_argc = argc; m.s_argv = argv; pthread_t threadGUI; //start a new thread for gui int result = pthread_create(&threadGUI, NULL, guifunc, (void *) &m); if (result) { printf("Error creating gui thread"); exit(0); } return 0; } void *guifunc(void * arg) { mas m = *(mas *)arg; QApplication app(m.s_argc,m.s_argv); //object instantiation guiClass *gui = new guiClass(); //show gui gui-show(); app.exec(); }

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