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  • Memory leaks after using typeinfo::name()

    - by icabod
    I have a program in which, partly for informational logging, I output the names of some classes as they are used (specifically I add an entry to a log saying along the lines of Messages::CSomeClass transmitted to 127.0.0.1). I do this with code similar to the following: std::string getMessageName(void) const { return std::string(typeid(*this).name()); } And yes, before anyone points it out, I realise that the output of typeinfo::name is implementation-specific. According to MSDN The type_info::name member function returns a const char* to a null-terminated string representing the human-readable name of the type. The memory pointed to is cached and should never be directly deallocated. However, when I exit my program in the debugger, any "new" use of typeinfo::name() shows up as a memory leak. If I output the information for 2 classes, I get 2 memory leaks, and so on. This hints that the cached data is never being freed. While this is not a major issue, it looks messy, and after a long debugging session it could easily hide genuine memory leaks. I have looked around and found some useful information (one SO answer gives some interesting information about how typeinfo may be implemented), but I'm wondering if this memory should normally be freed by the system, or if there is something i can do to "not notice" the leaks when debugging. I do have a back-up plan, which is to code the getMessageName method myself and not rely on typeinfo::name, but I'd like to know anyway if there's something I've missed.

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  • Universal oAuth for objective-c class?

    - by phpnerd211
    I have an app that connects to 6+ social networks via APIs. What I want to do is transfer over my oAuth calls to call directly from the phone (not from the server). Here's what I have (for tumblr): // Set some variables NSString *consumerKey = CONSUMER_KEY_HERE; NSString *sharedSecret = SHARED_SECRET_HERE; NSString *callToURL = @"https://tumblr.com/oauth/access_token"; NSString *thePassword = PASSWORD_HERE; NSString *theUsername = USERNAME_HERE; // Calculate nonce & timestamp NSString *nonce = [[NSString stringWithFormat:@"%d", arc4random()] retain]; time_t t; time(&t); mktime(gmtime(&t)); NSString *timestamp = [[NSString stringWithFormat:@"%d", (int)(((float)([[NSDate date] timeIntervalSince1970])) + 0.5)] retain]; // Generate signature NSString *baseString = [NSString stringWithFormat:@"GET&%@&%@",[callToURL urlEncode],[[NSString stringWithFormat:@"oauth_consumer_key=%@&oauth_nonce=%@&oauth_signature_method=HMAC-SHA1&oauth_timestamp=%@&oauth_version=1.0&x_auth_mode=client_auth&x_auth_password=%@&x_auth_username=%@",consumerKey,nonce,timestamp,thePassword,theUsername] urlEncode]]; NSLog(@"baseString: %@",baseString); const char *cKey = [sharedSecret cStringUsingEncoding:NSASCIIStringEncoding]; const char *cData = [baseString cStringUsingEncoding:NSASCIIStringEncoding]; unsigned char cHMAC[CC_SHA256_DIGEST_LENGTH]; CCHmac(kCCHmacAlgSHA256, cKey, strlen(cKey), cData, strlen(cData), cHMAC); NSData *HMAC = [[NSData alloc] initWithBytes:cHMAC length:sizeof(cHMAC)]; NSString *signature = [HMAC base64EncodedString]; NSString *theUrl = [NSString stringWithFormat:@"%@?oauth_consumer_key=%@&oauth_nonce=%@&oauth_signature=%@&oauth_signature_method=HMAC-SHA1&oauth_timestamp=%@&oauth_version=1.0&x_auth_mode=client_auth&x_auth_password=%@&x_auth_username=%@",callToURL,consumerKey,nonce,signature,timestamp,thePassword,theUsername]; From tumblr, I get this error: oauth_signature does not match expected value I've done some forum scouring, and no oAuth for objective-c classes worked for what I want to do. I also don't want to have to download and implement 6+ social API classes into my project and do it that way.

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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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  • C++ compiler unable to find function (namespace related)

    - by CS student
    I'm working in Visual Studio 2008 on a C++ programming assignment. We were supplied with files that define the following namespace hierarchy (the names are just for the sake of this post, I know "namespace XYZ-NAMESPACE" is redundant): (MAIN-NAMESPACE){ a bunch of functions/classes I need to implement... (EXCEPTIONS-NAMESPACE){ a bunch of exceptions } (POINTER-COLLECTIONS-NAMESPACE){ Set and LinkedList classes, plus iterators } } The MAIN-NAMESPACE contents are split between a bunch of files, and for some reason which I don't understand the operator<< for both Set and LinkedList is entirely outside of the MAIN-NAMESPACE (but within Set and LinkedList's header file). Here's the Set version: template<typename T> std::ostream& operator<<(std::ostream& os, const MAIN-NAMESPACE::POINTER-COLLECTIONS-NAMESPACE::Set<T>& set) Now here's the problem: I have the following data structure: Set A Set B Set C double num It's defined to be in a class within MAIN-NAMESPACE. When I create an instance of the class, and try to print one of the sets, it tells me that: error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'const MAIN-NAMESPACE::POINTER-COLLECTIONS-NAMESPACE::Set' (or there is no acceptable conversion) However, if I just write a main() function, and create Set A, fill it up, and use the operator- it works. Any idea what is the problem? (note: I tried any combination of using and include I could think of).

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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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  • Handling Apache Thrift list/map Return Types in C++

    - by initzero
    First off, I'll say I'm not the most competent C++ programmer, but I'm learning, and enjoying the power of Thrift. I've implemented a Thrift Service with some basic functions that return void, i32, and list. I'm using a Python client controlled by a Django web app to make RPC calls and it works pretty well. The generated code is pretty straight forward, except for list returns: namespace cpp Remote enum N_PROTO { N_TCP, N_UDP, N_ANY } service Rcon { i32 ping() i32 KillFlows() i32 RestartDispatch() i32 PrintActiveFlows() i32 PrintActiveListeners(1:i32 proto) list<string> ListAllFlows() } The generated signatures from Rcon.h: int32_t ping(); int32_t KillFlows(); int32_t RestartDispatch(); int32_t PrintActiveFlows(); int32_t PrintActiveListeners(const int32_t proto); int64_t ListenerBytesReceived(const int32_t id); void ListAllFlows(std::vector<std::string> & _return); As you see, the ListAllFlows() function generated takes a reference to a vector of strings. I guess I expect it to return a vector of strings as laid out in the .thrift description. I'm wondering if I am meant to provide the function a vector of strings to modify and then Thrift will handle returning it to my client despite the function returning void. I can find absolutely no resources or example usages of Thrift list< types in C++. Any guidance would be appreciated.

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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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  • 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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  • overloading "<<" with a struct (no class) cout style

    - by monkeyking
    I have a struct that I'd like to output using either 'std::cout' or some other output stream. Is this possible without using classes? Thanks #include <iostream> #include <fstream> template <typename T> struct point{ T x; T y; }; template <typename T> std::ostream& dump(std::ostream &o,point<T> p) const{ o<<"x: " << p.x <<"\ty: " << p.y <<std::endl; } template<typename T> std::ostream& operator << (std::ostream &o,const point<T> &a){ return dump(o,a); } int main(){ point<double> p; p.x=0.1; p.y=0.3; dump(std::cout,p); std::cout << p ;//how? return 0; } I tried different syntax' but I cant seem to make it work.

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  • Clicking the mouse down to drag objects on Mac

    - by Uri
    I've been using the following code to issue clicks programmatically on a Mac void PostMouseEvent(CGMouseButton button, CGEventType type, const CGPoint point) { CGEventRef theEvent = CGEventCreateMouseEvent(NULL, type, point, button); CGEventSetType(theEvent, type); CGEventPost(kCGHIDEventTap, theEvent); CFRelease(theEvent); } void Click(const CGPoint point) { PostMouseEvent(kCGMouseButtonLeft, kCGEventMouseMoved, point); NSLog(@"Click!"); PostMouseEvent(kCGMouseButtonLeft, kCGEventLeftMouseDown, point); PostMouseEvent(kCGMouseButtonLeft, kCGEventLeftMouseUp, point); } Now, I'm trying to click down to be able to drag objects, like a scroll bar or an application's window. I'm using the following: PostMouseEvent(kCGMouseButtonLeft, kCGEventMouseMoved, point); NSLog(@"Click Down!"); PostMouseEvent(kCGMouseButtonLeft, kCGEventLeftMouseDown, point); When i ran the code above something interesting will happen, when the left mouse down is issue nothing seem to happen, I move my mouse and the window doesn't move, however when I added a mouse up event then the window jumped to the location where I supposedly dragged it. this is sort of OK, however, how do I can make the mouse click down and drag an object? Note: I do have a whole method to see when the mouse stopped moving so I can click up. please post code. Thanks

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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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  • Compile C++ in Visual Studio

    - by Kasun
    Hi All.. I use this method to compile C++ file in VS. But even i provide the correct file it returns false. Can any one help me... This is class called CL class CL { private const string clexe = @"cl.exe"; private const string exe = "Test.exe", file = "test.cpp"; private string args; public CL(String[] args) { this.args = String.Join(" ", args); this.args += (args.Length > 0 ? " " : "") + "/Fe" + exe + " " + file; } public Boolean Compile(String content, ref string errors) { if (File.Exists(exe)) File.Delete(exe); if (File.Exists(file)) File.Delete(file); File.WriteAllText(file, content); Process proc = new Process(); proc.StartInfo.UseShellExecute = false; proc.StartInfo.RedirectStandardOutput = true; proc.StartInfo.RedirectStandardError = true; proc.StartInfo.FileName = clexe; proc.StartInfo.Arguments = this.args; proc.StartInfo.CreateNoWindow = true; proc.Start(); //errors += proc.StandardError.ReadToEnd(); errors += proc.StandardOutput.ReadToEnd(); proc.WaitForExit(); bool success = File.Exists(exe); return success; } } This is my button click event private void button1_Click(object sender, EventArgs e) { string content = "#include <stdio.h>\nmain(){\nprintf(\"Hello world\");\n}\n"; string errors = ""; CL k = new CL(new string[] { }); if (k.Compile(content, ref errors)) Console.WriteLine("Success!"); else MessageBox.Show("Errors are : ", errors); }

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  • C++ Template problem adding two data types

    - by Sara
    I have a template class with an overloaded + operator. This is working fine when I am adding two ints or two doubles. How do I get it to add and int and a double and return the double? template <class T> class TemplateTest { private: T x; public: TemplateTest<T> operator+(const TemplateTest<T>& t1)const { return TemplateTest<T>(x + t1.x); } } in my main function i have void main() { TemplateTest intTt1 = TemplateTest<int>(2); TemplateTest intTt2 = TemplateTest<int>(4); TemplateTest doubleTt1 = TemplateTest<double>(2.1d); TemplateTest doubleTt2 = TemplateTest<double>(2.5d); std::cout << intTt1 + intTt2 << /n; std::cout << doubleTt1 + doubleTt2 << /n; } I want to be able to also do this std::cout << doubleTt1 + intTt2 << /n;

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  • How to Populate a 'Tree' structure 'Declaratively'

    - by mackenir
    I want to define a 'node' class/struct and then declare a tree of these nodes in code in such a way that the way the code is formatted reflects the tree structure, and there's not 'too much' boiler plate in the way. Note that this isn't a question about data structures, but rather about what features of C++ I could use to arrive at a similar style of declarative code to the example below. Possibly with C++0X this would be easier as it has more capabilities in the area of constructing objects and collections, but I'm using Visual Studio 2008. Example tree node type: struct node { string name; node* children; node(const char* name, node* children); node(const char* name); }; What I want to do: Declare a tree so its structure is reflected in the source code node root = node("foo", [ node("child1"), node("child2", [ node("grand_child1"), node("grand_child2"), node("grand_child3" ]), node("child3") ]); NB: what I don't want to do: Declare a whole bunch of temporary objects/colls and construct the tree 'backwards' node grandkids[] = node[3] { node("grand_child1"), node("grand_child2"), node("grand_child3" }; node kids[] = node[3] { node("child1"), node("child2", grandkids) node("child3") }; node root = node("foo", kids);

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  • c++ specialized overload?

    - by acidzombie24
    -edit- i am trying to close the question. i solved the problem with boost::is_base_and_derived In my class i want to do two things. 1) Copy int, floats and other normal values 2) Copy structs that supply a special copy function (template T copyAs(); } the struct MUST NOT return int's unless i explicitly say ints. I do not want the programmer mistaking the mistake by doing int a = thatClass; -edit- someone mention classes dont return anything, i mean using the operator Type() overload. How do i create my copy operator in such a way i can copy both 1) ints, floats etc and the the struct restricted in the way i mention in 2). i tried doing template <class T2> T operator = (const T2& v); which would cover my ints, floats etc. But how would it differentiate from structs? so i wrote T operator = (const SomeGenericBase& v); The idea was the GenericBase would be unsed instead then i can do v.Whatever. But that backfires bc the functions i want wouldnt exist, unless i use virtual, but virtual templates dont exist. Also i would hate to use virtual I think the solution is to get rid of ints and have it convert to something that can do .as(). So i wrote something up but now i have the same problem, how does that differentiate ints and structs that have the .as() function template?

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  • streaming xml pretty printer in C/C++ using expat or libxml2?

    - by Mark Zeren
    I have a library that outputs xml without whitespace all on one line. In some cases I'd like to pretty print that output. I'm looking for a BSD-ish licensed C/C++ library or sample code that will take a raw xml byte stream and pretty print it. Here's some pseudo code showing one way that I might use this functionality: void my_write(const char* buf, int len); PrettyPrinter pp(bind(&my_write)); while (...) { // ... get some more xml ... const char* buf = xmlSource.get_buf(); int len = xmlSource.get_buf_len(); int written = pp.write(buf, len); // calls my_write with pretty printed xml // ... error handling, maybe call write again, etc. ... } I'd like to avoid instantiating a DOM representation. I already have dependencies on the expat and libxml2 shared libraries, and I'd rather not add any more shared library dependencies.

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  • C++: Copy contructor: Use Getters or access member vars directly?

    - by cbrulak
    Have a simple container class: public Container { public: Container() {} Container(const Container& cont) //option 1 { SetMyString(cont.GetMyString()); } //OR Container(const Container& cont) //option 2 { m_str1 = cont.m_str1; } public string GetMyString() { return m_str1;} public void SetMyString(string str) { m_str1 = str;} private: string m_str1; } So, would you recommend this method or accessing the member variables directly? In the example, all code is inline, but in our real code there is no inline code. Update (29 Sept 09): Some of these answers are well written however they seem to get missing the point of this question: this is simple contrived example to discuss using getters/setters vs variables initializer lists or private validator functions are not really part of this question. I'm wondering if either design will make the code easier to maintain and expand. Some ppl are focusing on the string in this example however it is just an example, imagine it is a different object instead. I'm not concerned about performance. we're not programming on the PDP-11

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  • std::stringstream GCC Abnormal Behavior

    - by FlorianZ
    I have a very interesting problem with compiling a short little program on a Mac (GCC 4.2). The function below would only stream chars or strings into the stringstream, but not anything else (int, double, float, etc.) In fact, the fail flag is set if I attempt to convert for example an int into a string. However, removing the preprocessor flag: _GLIBCXX_DEBUG=1, which is set by default in XCode for the debug mode, will yield the desired results / correct behavior. Here is the simple function I am talking about. value is template variable of type T. Tested for int, double, float (not working), char and strings (working). template < typename T > const std::string Attribute<T>::getValueAsString() const { std::ostringstream stringValue; stringValue << value; return stringValue.str(); } Any ideas what I am doing wrong, why this doesn't work, or what the preprocessor flag does to make this not work anymore? Thanks!

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  • VC9 C1083 Cannot open include file: 'boost...' after trying to abstract an include dependency

    - by ronivek
    Hey, So I've been working on a project for the past number of weeks and it uses a number of Boost libraries. In particular I'm using the boost::dynamic_bitset library quite extensively. I've had zero issues up until now; but tonight I discovered a dependency between some includes which I had to resolve; and I tried to do so by providing an abstract callback class. Effectively I now have the following: First include... class OtherClassCallback { public: virtual int someOtherMethod() const = 0; }; class SomeClass { public: void someMethod(OtherClassCallback *oc) { ... oc->someOtherMethod(); ... } }; Second include... #include "SomeClass.h" class SomeOtherClass : public OtherClassCallback { public: int someOtherMethod() const { return this->someInt; } }; Here is the issue; ever since I implemented this class I'm now getting the following error: fatal error C1083: Cannot open include file: 'boost/dynamic_bitset/dynamic_bitset.hpp': No such file or directory Now I'm getting no other compiler errors; and it's a pretty substantial project. My include paths and so on are perfect; my files are fully accessible and removing the changes fixes the issue. Does anyone have any idea what might be going on? I'm compiling to native Windows executables in VS9. I should confess that I'm very inexperienced with C++ in general so go easy on me if it's something horribly straightforward; I can't figure it out.

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  • Preprocessor #define vs. function pointer - best practice?

    - by Dustin
    I recently started a small personal project (RGB value to BGR value conversion program) in C, and I realised that a function that converts from RGB to BGR can not only perform the conversion but also the inversion. Obviously that means I don't really need two functions rgb2bgr and bgr2rgb. However, does it matter whether I use a function pointer instead of a macro? For example: int rgb2bgr (const int rgb); /* * Should I do this because it allows the compiler to issue * appropriate error messages using the proper function name, * not to mention possible debugging benefits? */ int (*bgr2rgb) (const int bgr) = rgb2bgr; /* * Or should I do this since it is merely a convenience * and they're really the same function anyway? */ #define bgr2rgb(bgr) (rgb2bgr (bgr)) I'm not necessarily looking for a change in execution efficiency as it's more of a subjective question out of curiosity. I am well aware of the fact that type safety is neither lost nor gained using either method. Would the function pointer merely be a convenience or are there more practical benefits to be gained of which I am unaware?

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  • c++ STL vector is not acccepting the copy constructor

    - by prabhakaran
    I wrote a code ( c++,visual studio 2010) which is having a vector, even I though copy const is declared, but is still showing that copy const is not declared Here the code #include<iostream> #include<vector> using namespace std; class A { public: A(){cout << "Default A is acting" << endl ;} A(A &a){cout << "Copy Constructor of A is acting" << endl ;} }; int main() { A a; A b=a; vector<A> nothing; nothing.push_back(a); int n; cin >> n; } The error I got is Error 1 error C2558: class 'A' : no copy constructor available or copy constructor is declared 'explicit' c:\program files\microsoft visual studio 10.0\vc\include\xmemory 48 1 delete Anybody please help me

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  • Convert enumeration to string

    - by emptyheaded
    I am trying to build a function that converts an item from an enum to its corresponding string. The enums I use are fairly long, so I didn't want to use a switch-case. I found a method using boost::unordered_map very convenient, but I don't know how to make a default return (when there is no item matching the enum). const boost::unordered_map<enum_type, const std::string> enumToString = boost::assign::map_list_of (data_1, "data_1") (data_2, "data_2"); I tried to create an additional function: std::string convert(enum_type entry) { if (enumToString.find(entry)) // not sure what test to place here, return enumToString.at(entry); //because the find method returns an iter else return "invalid_value"; } I even tried something exceedingly wrong: std::string convert(enum_type entry) { try{ return enumToString.at(entry); } catch(...){ return "invalid_value"; } } Result: evil "Debug" runtime error. Can somebody give me a suggestion on how to either 1) find an easier method to convert enum to a string with the same name as the enum item 2) find a way to use already built boost methods to get a default value from a hash map (best option) 3) find what to place in the test to use a function that returns either the pair of the key-value, or a different string if the key is not found in the map. Thank you very much.

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  • insert data using sqlite issue on iphone ( not reflecting on table)

    - by prajakta
    i can insert my data but i cant show them on my table view ..i did [tableview reload data] but of no success here is my code -(void)gButtonTapped:(id)sender { NSLog(@"right nav bar button is hit%@ ",storePaths); //[self readAnimalsFromDatabase2]; appDelegate = (DatabaseTestAppDelegate *)[[UIApplication sharedApplication] delegate]; sqlite3 *database; sqlite3_stmt *compiled_statement1; if(sqlite3_open([storePaths UTF8String], &database) == SQLITE_OK) { //const char *sqlStatement = NSString *newQuery = [NSString stringWithFormat:@"insert into cat_tbl (cat_id,names,imgs) values ('12','test1','r.png')"]; // NSString *newQuery = [NSString stringWithFormat:@"select * from list_tbl"]; const char *sql = [newQuery cStringUsingEncoding:NSASCIIStringEncoding]; NSLog(@"update query is %@",newQuery); if(sqlite3_prepare_v2(database, sql, -1, &compiled_statement1, NULL) == SQLITE_OK) { int result = sqlite3_step(compiled_statement1); sqlite3_reset(compiled_statement1); NSLog(@"result %d", result); if(result != SQLITE_ERROR) { int lastInsertId = sqlite3_last_insert_rowid(database); NSLog(@"x %d", lastInsertId); } } } sqlite3_finalize(compiled_statement1); sqlite3_close(database); [tabelView reloadData];// this is also not working }

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  • What is the purpose of the QAbstractButton::checkStateSet() method?

    - by darkadept
    I'm writing my own 4 state button and I'm not quite sure what to put in the checkStateSet() method, if anything. Here is what I've got so far: SyncDirectionButton::SyncDirectionButton(QWidget *parent) : QAbstractButton(parent) { setCheckable(true); setToolTip(tr("Click to change the sync direction")); _state = NoSync; } void SyncDirectionButton::paintEvent(QPaintEvent *e) { static QPixmapCache::Key noneKey; static QPixmapCache::Key bothKey; static QPixmapCache::Key leftKey; static QPixmapCache::Key rightKey; QPainter p(this); QPixmap pix; if (checkState() == SyncLeft) { if (!QPixmapCache::find(leftKey, &pix)) { pix.load(":/icons/sync-left.png"); leftKey = QPixmapCache::insert(pix); } } else if (checkState() == SyncBoth) { if (!QPixmapCache::find(rightKey, &pix)) { pix.load(":/icons/sync-right.png"); rightKey = QPixmapCache::insert(pix); } } else if (checkState() == SyncRight) { if (!QPixmapCache::find(bothKey, &pix)) { pix.load(":/icons/sync-both.png"); bothKey = QPixmapCache::insert(pix); } } else if (checkState() == NoSync) { if (!QPixmapCache::find(noneKey, &pix)) { pix.load(":/icons/application-exit.png"); noneKey = QPixmapCache::insert(pix); } } p.drawPixmap(0,0,pix); } SyncDirectionButton::DirectionState SyncDirectionButton::checkState() const { return _state; } void SyncDirectionButton::setCheckState(DirectionState state) { setChecked(state != NoSync); if (state != _state) { _state = state; } } QSize SyncDirectionButton::sizeHint() const { return QSize(180,90); } void SyncDirectionButton::checkStateSet() { } void SyncDirectionButton::nextCheckState() { setCheckState((DirectionState)((checkState()+1)%4)); }

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  • Compile time type determination in C++

    - by dicroce
    A coworker recently showed me some code that he found online. It appears to allow compile time determination of whether a type has an "is a" relationship with another type. I think this is totally awesome, but I have to admit that I'm clueless as to how this actually works. Can anyone explain this to me? template<typename BaseT, typename DerivedT> inline bool isRelated(const DerivedT&) { DerivedT derived(); char test(const BaseT&); // sizeof(test()) == sizeof(char) char (&test(...))[2]; // sizeof(test()) == sizeof(char[2]) struct conversion { enum { exists = (sizeof(test(derived())) == sizeof(char)) }; }; return conversion::exists; } Once this function is defined, you can use it like this: #include <iostream> class base {}; class derived : public base {}; class unrelated {}; int main() { base b; derived d; unrelated u; if( isRelated<base>( b ) ) std::cout << "b is related to base" << std::endl; if( isRelated<base>( d ) ) std::cout << "d is related to base" << std::endl; if( !isRelated<base>( u ) ) std::cout << "u is not related to base" << std::endl; }

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