Search Results

Search found 2566 results on 103 pages for 'struct'.

Page 88/103 | < Previous Page | 84 85 86 87 88 89 90 91 92 93 94 95  | Next Page >

• How to create an array of buttons in C++

  - by mangoman13

  Hi, I'm using C++ in VS2005 and have an 8x8 grid of buttons on a form. I want to have these buttons in an array, so when I click on any of them it will open the same event handler (I think that is what they are called), but I will know the index of which one was clicked on. I know how to do this in VB and C#, but I can't seem to figure it out with C++ Right now I have all my buttons labelled by their location, i.e. b00, b10, b21, etc. So I think what I am looking for is a way to do something like this: Button b[8][8]; //this causes me errors (error C2728: 'System::Windows::Forms::Button' : a native array cannot contain this managed type) and (error C2227: left of '->{ctor}' must point to class/struct/union/generic type) void Assignment(){ b[0][0] = b00; b[1][0] = b10; ... } and then in form1.h: private: System::Void b_Click(System::Object^ sender, System::EventArgs^ e) { //somehow read the coordinates into variables x and y //do something based on these values } Any help would be appreciated. Also let me know if I am going in the complete wrong direction with this. Thanks!

  Read the article

• Fast sketching tools for drawing C/C++ structs, pointers, etc...

  - by tomasorti

  Hi. I would like to know what do you use to sketch relations between different entities in C/C++. This can be a very broad issue, so I'll try to clarify a bit more my question and give an example. I'm looking for something that is simple enough as a user, and let me sketch easily containers, pointers, etc... in an informal way. The aim is to document some structs relations to pass them to junior developers. A look at the drawings is supposed to accelerate the understanding of the code. My solutions at this moment are to use: 1) Paper & pencil. 2) Microsoft PowerPoint/Word Autoshapes. 3) Freeware Dia. Other ones could be: 4) Microsoft Visio, but my company does not own licenses. 5) UML tools. I don't want to go this way. This is what I mean a more formal solution. I know tools like Rational Rose are great, and I tried boUML and violet and they are fine in some parts, but I prefer the flexibility of options 2) or 3). Finally, let me write down a more concrete example: Let's say I what to sketch a map that contains another map as the mapped value, and that one contains a struct as the mapped value, that holds a vector of pointers of a type and a pointer to other type. Also, there exist other structs that hold pointers to the objects pointed by the previous map, so there are objects pointed from different places. This is just one example I have, but you can easily come with one from you experience. What would you use to sketch this example or another similar you have dealt with? Best regards, Tomas.

  Read the article

• How to enforce users to create objects of class derived from mine with "new" only?

  - by sharptooth

  To implement reference counting we use an IUnknown-like interface and a smart pointer template class. The interface has implementation for all the reference-count methods, including Release(): void IUnknownLike::Release() { if( --refCount == 0 ) { delete this; } } The smart pointer template class has a copy constructor and an assignment operator both accepting raw pointers. So users can do the following: class Class : public IUnknownLike { }; void someFunction( CSmartPointer<Class> object ); //whatever function Class object; someFunction( &object ); and the program runs into undefined behavior - the object is created with reference count zero, the smart pointer is constructed and bumps it to one, then the function returns, smart pointer is destroyed, calls Release() which leads to delete of a stack-allocated variable. Users can as well do the following: struct COuter { //whatever else; Class inner;// IUnknownLike descendant }; COuter object; somefunction( &object.Inner ); and again an object not created with new is deleted. Undefined behavior at its best. Is there any way to change the IUnknownLike interface so that the user is forced to use new for creating all objects derived from IUnknownLike - both directly derived and indirectly derived (with classes in between the most derived and the base)?

  Read the article

• What is the merit of the "function" type (not "pointer to function")

  - by anatolyg

  Reading the C++ Standard, i see that there are "function" types and "pointer to function" types: typedef int func(int); // function typedef int (*pfunc)(int); // pointer to function typedef func* pfunc; // same as above I have never seen the function types used outside of examples (or maybe i didn't recognize their usage?). Some examples: func increase, decrease; // declares two functions int increase(int), decrease(int); // same as above int increase(int x) {return x + 1;} // cannot use the typedef when defining functions int decrease(int x) {return x - 1;} // cannot use the typedef when defining functions struct mystruct { func add, subtract, multiply; // declares three member functions int member; }; int mystruct::add(int x) {return x + member;} // cannot use the typedef int mystruct::subtract(int x) {return x - member;} int main() { func k; // the syntax is correct but the variable k is useless! mystruct myobject; myobject.member = 4; cout << increase(5) << ' ' << decrease(5) << '\n'; // outputs 6 and 4 cout << myobject.add(5) << ' ' << myobject.subtract(5) << '\n'; // 9 and 1 } Seeing that the function types support syntax that doesn't appear in C (declaring member functions), i guess they are not just a part of C baggage that C++ has to support for backward compatibility. So is there any use for function types, other than demonstrating some funky syntax?

  Read the article

• Go - Using a map for its set properties with user defined types

  - by Seth Hoenig

  I'm trying to use the built-in map type as a set for a type of my own (Point, in this case). The problem is, when I assign a Point to the map, and then later create a new, but equal point and use it as a key, the map behaves as though that key is not in the map. Is this not possible to do? // maptest.go package main import "fmt" func main() { set := make(map[*Point]bool) printSet(set) set[NewPoint(0, 0)] = true printSet(set) set[NewPoint(0, 2)] = true printSet(set) _, ok := set[NewPoint(3, 3)] // not in map if !ok { fmt.Print("correct error code for non existent element\n") } else { fmt.Print("incorrect error code for non existent element\n") } c, ok := set[NewPoint(0, 2)] // another one just like it already in map if ok { fmt.Print("correct error code for existent element\n") // should get this } else { fmt.Print("incorrect error code for existent element\n") // get this } fmt.Printf("c: %t\n", c) } func printSet(stuff map[*Point]bool) { fmt.Print("Set:\n") for k, v := range stuff { fmt.Printf("%s: %t\n", k, v) } } type Point struct { row int col int } func NewPoint(r, c int) *Point { return &Point{r, c} } func (p *Point) String() string { return fmt.Sprintf("{%d, %d}", p.row, p.col) } func (p *Point) Eq(o *Point) bool { return p.row == o.row && p.col == o.col }

  Read the article

• Difference in behaviour (GCC and Visual C++)

  - by Prasoon Saurav

  Consider the following code. #include <stdio.h> #include <vector> #include <iostream> struct XYZ { int X,Y,Z; }; std::vector<XYZ> A; int rec(int idx) { int i = A.size(); A.push_back(XYZ()); if (idx >= 5) return i; A[i].X = rec(idx+1); return i; } int main(){ A.clear(); rec(0); puts("FINISH!"); } I couldn't figure out the reason why the code gives a segmentation fault on Linux (IDE used: Code::Blocks) whereas on Windows (IDE used: Visual C++) it doesn't. When I used Valgrind just to check what actually the problem was, I got this output. I got Invalid write of size 4 at four different places. Then why didn't the code crash when I used Visual C++? Am I missing something?

  Read the article

• Difference in behaviour( gcc and MSVC++ )

  - by Prasoon Saurav

  Consider the following code. #include <stdio.h> #include <vector> #include <iostream> struct XYZ { int X,Y,Z; }; std::vector<XYZ> A; int rec(int idx) { int i = A.size(); A.push_back(XYZ()); if (idx >= 5) return i; A[i].X = rec(idx+1); return i; } int main(){ A.clear(); rec(0); puts("FINISH!"); } I couldn't figure out the reason why the code gives segmentation fault on Linux(IDE used: Code::Blocks) whereas on Windows(IDE used : MSVC++) it doesn't. When I used valgrind just to check what actually the problem was, I got this output. I got Invalid write of size 4 at four different places. Then why didn't the code crash when I used MSVC++? Am I missing something?

  Read the article

• Why Does My Vector<PEVENTLOGRECORD> Mysteriously Get Cleared?

  - by Eric

  Hello everyone, I am making a program that reads and stores data from Windows EventLog files (.evt) in C++. I am using the calls OpenBackupEventLog(ServerName, FileName) and ReadEventLog(...). Also using this: PEVENTLOGRECORD Anyway, without supplying all of the code, here is the basic idea: 1. I get a handle to the .evt file using OpenBackupEventLog() and passing in a file name. 2. I then use ReadEventLog() to fill up a buffer with an unknown number of EventLog messages. 3. I traverse through the buffer and add each message to a vector 4. I keep filling up buffers (repeat steps 2 and 3) until I reach the end of the file. Here is my code for filling the vector: vector<PEVENTLOGRECORD> allRecords; while(_status == ERROR_SUCCESS) { if(!ReadEventLog(...)) CheckStatus(); else FillVectorFromBuffer(allRecords) } // Function FillVectorFromBuffer FillVectorFromBuffer(vector(PEVENTLOGRECORD) &allRecords) { int bytesExamined = 0; PBYTE pRecord = (PBYTE)_lpBuffer; // This is one of the params in ReadEventLog() while(bytesExamined < _pnBytesRead) // Another param from ReadEventLog { PEVENTLOGRECORD currentRecord = (PEVENTLOGRECORD)(pRecord); allRecords.push_back(currentRecord); pRecord += currentRecord->Length; bytesExamined += currentRecord->Length; } } Anyway, whenever I run this, it will get all the EventLogs in the file, and the vector will have everything I want it to. But as soon as this line: if(!ReadEventLog()) gets called and returns true (aka ReadEventLog() returns false), then every field in my vector gets set to zero. The vector will still contain the correct number of elements, it's just that all of the fields in the PEVENTLOGRECORD struct are now zero. Anyone with better debugging experience have any ideas? Thanks.

  Read the article

• Presenting collection of structures of strings in grid or similar in WPF - Example? Ideas?

  - by Andrew

  Hi, I have a collection of structures. The structure is just some strings. Example public struct ReportLine { public string Name; public string Address; public string Phone; ...// about 10 other strings } I can't change this part. What I want to do is display it in a simple grid or simlar in WPF. My only requirements are: a) need column headers b) rows must alternate in color c) columns big enough to hold largest datum (which is not know until run time) Can someone point me to an example to get me started? Is the GridView the way to go? Or DataGrid? Or perhaps just the grid? I have the book Pro WPF in C# 2008 and it covers binding ListBox's to collections, but the collections always seem to be collections of one field (ex. a collection of 40 names). Here I have a collection (an array in fact) of a structure. How do I setup the databinding? As you can see, I'm new to this and probably would most benefit from a reference to an article. I've found articles covering collections of 1 field, but no examples covering binding to an array of structures. Also, my intitial research indicates c) can't be easily done, if you demand that the column is big enough for all the data in that column, not just the visible data. Thanks, dave

  Read the article

• Regarding the ViewModel

  - by mizipzor

  Im struggling to understand the ViewModel part of the MVVM pattern. My current approach is to have a class, with no logic whatsoever (important), except that it implements INotifyPropertyChanged. The class is just a collection of properties, a struct if you like, describing an as small part of the data as possible. I consider this my Model. Most of the WPF code I write are settings dialogs that configure said Model. The code-behind of the dialog exposes a property which returns an instance of the Model. In the XAML code I bind to subproperties of that property, thereby binding directly to the Model's properties. Which works quite well since it implements the INotifyPropertyChanged. I consider this settings dialog the View. However, I havent really been able to figure out what in all this is the ViewModel. The articles Ive read suggests that the ViewModel should tie the View and the Model together, providing the logic the Model lacks but is still to complex to go directly into the View. Is this correct? Would, in my example, the code-behind of the settings dialog be considered the ViewModel? I just feel a bit lost and would like my peers to debunk some of my assumptions. Am I completely off track here?

  Read the article

• [C++] My First Go With Function Templates

  - by bobber205

  Thought it was pretty straight forward. But I get a "iterator not dereferencable" errro when running the below code. What's wrong? template<typename T> struct SumsTo : public std::binary_function<T, T, bool> { int myInt; SumsTo(int a) { myInt = a; } bool operator()(const T& l, const T& r) { cout << l << " + " << r; if ((l + r) == myInt) { cout << " does add to " << myInt; } else { cout << " DOES NOT add to " << myInt; } return true; } }; void main() { list<int> l1; l1.push_back(1); l1.push_back(2); l1.push_back(3); l1.push_back(4); list<int> l2; l2.push_back(9); l2.push_back(8); l2.push_back(7); l2.push_back(6); transform(l1.begin(), l1.end(), l2.begin(), l2.end(), SumsTo<int>(10) ); }

  Read the article

• Nullable<T> as a parameter

  - by ferch

  I alredy have this: public static object GetDBValue(object ObjectEvaluated) { if (ObjectEvaluated == null) return DBNull.Value; else return ObjectEvaluated; } used like: List<SqlParameter> Params = new List<SqlParameter>(); Params.Add(new SqlParameter("@EntityType", GetDBValue(EntityType))); Now i wanted to keep the same interface but extend that to use it with nullable public static object GetDBValue(int? ObjectEvaluated) { if (ObjectEvaluated.HasValue) return ObjectEvaluated.Value; else return DBNull.Value; } public static object GetDBValue(DateTime? ObjectEvaluated) {...} but i want only 1 function GetDBValue for nullables. How do I do that and keep the call as is is? Is that possible at all? I can make it work like: public static object GetDBValue<T>(Nullable<T> ObjectEvaluated) where T : struct { if (ObjectEvaluated.HasValue) return ObjectEvaluated.Value; else return DBNull.Value; } But the call changes to: Params.Add(new SqlParameter("@EntityID ", GetDBValue<int>(EntityID)));

  Read the article

• How to use boost::fusion::transform on heterogeneous containers?

  - by Kyle

  Boost.org's example given for fusion::transform is as follows: struct triple { typedef int result_type; int operator()(int t) const { return t * 3; }; }; // ... assert(transform(make_vector(1,2,3), triple()) == make_vector(3,6,9)); Yet I'm not "getting it." The vector in their example contains elements all of the same type, but a major point of using fusion is containers of heterogeneous types. What if they had used make_vector(1, 'a', "howdy") instead? int operator()(int t) would need to become template<typename T> T& operator()(T& const t) But how would I write the result_type? template<typename T> typedef T& result_type certainly isn't valid syntax, and it wouldn't make sense even if it was, because it's not tied to the function.

  Read the article

• Error_No_Token by adding printer driver (c#)

  - by user1686388

  I'm trying to add printer drivers using the windows API function AddPrinterDriver. The Win32 error 1008 (An attempt was made to reference a token that does not exist.) was always generated. My code is shown as following [DllImport("Winspool.drv")] static extern bool AddPrinterDriver(string Name, Int32 Level, [in] ref DRIVER_INFO_3 DriverInfo); [StructLayout(LayoutKind.Sequential)] public struct DRIVER_INFO_3 { public Int32 cVersion; public string Name; public string Environment; public string DriverPath; public string DataFile; public string ConfigFile; public string HelpFile; public string DependentFiles; public string MonitorName; public string DefaultDataType; } //....................... DRIVER_INFO_3 di = new DRIVER_INFO_3(); //...................... AddPrinterDriver(Environment.MachineName, 3, ref di); I have also tried to get a token by "ImpersonateSelf" before adding the printer driver. But the error 1008 insists. Does anyone have an idea? best regards.

  Read the article

• Reverse reading WORD from a binary file?

  - by Angel

  Hi, I have a structure: struct JFIF_HEADER { WORD marker[2]; // = 0xFFD8FFE0 WORD length; // = 0x0010 BYTE signature[5]; // = "JFIF\0" BYTE versionhi; // = 1 BYTE versionlo; // = 1 BYTE xyunits; // = 0 WORD xdensity; // = 1 WORD ydensity; // = 1 BYTE thumbnwidth; // = 0 BYTE thumbnheight; // = 0 }; This is how I read it from the file: HANDLE file = CreateFile(filename, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0); DWORD tmp = 0; DWORD size = GetFileSize(file, &tmp); BYTE *DATA = new BYTE[size]; ReadFile(file, DATA, size, &tmp, 0); JFIF_HEADER header; memcpy(&header, DATA, sizeof(JFIF_HEADER)); This is how the beginning of my file looks in hex editor: 0xFF 0xD8 0xFF 0xE0 0x00 0x10 0x4A 0x46 0x49 0x46 0x00 0x01 0x01 0x00 0x00 0x01 When I print header.marker, it shows exactly what it should (0xFFD8FFE0). But when I print header.length, it shows 0x1000 instead of 0x0010. The same thing is with xdensity and ydensity. Why do I get wrong data when reading a WORD? Thank you.

  Read the article

• Is it poor design to create objects that only execute code during the constructor?

  - by Curtix

  In my design I am using objects that evaluate a data record. The constructor is called with the data record and type of evaluation as parameters and then the constructor calls all of the object's code necessary to evaluate the record. This includes using the type of evaluation to find additional parameter-like data in a text file. There are in the neighborhood of 250 unique evaluation types that use the same or similar code and unique parameters coming from the text file. Some of these evaluations use different code so I benefit a lot from this model because I can use inheritance and polymorphism. Once the object is created there isn't any need to execute additional code on the object (at least for now) and it is used more like a struct; its kept on a list and 3 properties are used later. I think this design is the easiest to understand, code, and read. A logical alternative I guess would be using functions that return score structs, but you can't inherit from methods so it would make it kind of sloppy imo. I am using vb.net and these classes will be used in an asp.net web app as well as in a distributed app. thanks for your input

  Read the article

• libcurl (c api) READFUNCTION for http PUT blocking forever

  - by Duane

  I am using libcurl for a RESTful library. I am having two problems with a PUT message, I am just trying to send a small content like "hello" via put. My READFUNCTION for PUT's blocks for a very large amount of time (minutes) when I follow the manual at curl.haxx.se and return a 0 indicating I have finished the content. (on os X) When I return something 0 this succeeds much faster (< 1 sec) When I run this on my linux machine (ubuntu 10.4) this blocking event appears to NEVER return when I return 0, if I change the behavior to return the size written libcurl appends all the data in the http body sending way more data and it fails with a "too much data" message from the server. my readfunction is below, any help would be greatly appreciated. I am using libcurl 7.20.1 typedef struct{ void *data; int body_size; int bytes_remaining; int bytes_written; } postdata; size_t readfunc(void *ptr, size_t size, size_t nmemb, void *stream) { if(stream) { postdata ud = (postdata)stream; if(ud->bytes_remaining) { if(ud->body_size > size*nmemb) { memcpy(ptr, ud->data+ud->bytes_written, size*nmemb); ud->bytes_written+=size+nmemb; ud->bytes_remaining = ud->body_size-size*nmemb; return size*nmemb; } else { memcpy(ptr, ud->data+ud->bytes_written, ud->bytes_remaining); ud->bytes_remaining=0; return 0; } }

  Read the article

• How to use two parameters pointing to the same structure in one function ?

  - by ZaZu

  Hey guys, I have my code below that consits of a structure, a main, and a function. The function is supposed to display two parameters that have certain values, both of which point to the same structure. The problem I dont know how to add the SECOND parameter onto the following code : #include<stdio.h> #define first 500 #define sec 500 struct trial{ int f; int r; float what[first][sec]; }; int trialtest(trial *test); main(){ trial test; trialtest(&test); } int trialtest(trial *test){ int z,x,i; for(i=0;i<5;i++){ printf("%f,(*test).what[z][x]); } return 0; } I need to add a new parameter test_2 there (IN THE SAME FUNCTION) using this code : for(i=0;i<5;i++){ printf("%f,(*test_2).what[z][x]); How does int trialtest(trial *test) changes ? and how does it change in main ? I know that I should declare test_2 as well, like this : trial test,test_2; But what about passing the address in the function ? I do not need to edit it right ? trialtest(&test); --- This will remain the same ? So please, tell me how would I use test_2 as a parameter pointing to the same structure as test, both in the same function.. Thank you !! Please tell me if you need more clarification

  Read the article

• Rails problem with Delayed_Job and Active Record

  - by Michael Waxman

  I'm using Delayed_Job to grab a Twitter user's data from the API, but it's not saving it in the model for some reason! Please help! (code below) class BandJob < Struct.new(:band_id, :band_username) #parameter def perform require 'json' require 'open-uri' band = Band.find_by_id(band_id) t = JSON.parse(open("http://twitter.com/users/show/#{band_username}.json").read) band.screen_name = t['screen_name'] band.profile_background_image = t['profile_background_image_url'] band.url = 'http://' + band_username + '.com' band.save! end end To clarify, I'm actually not getting any errors, it's just not saving. Here's what my log looks like: * [JOB] acquiring lock on BandJob [4;36;1mDelayed::Job Update (3.1ms)[0m [0;1mUPDATE "delayed_jobs" SET locked_at = '2009-11-09 18:59:45', locked_by = 'host:dhcp128036151228.central.yale.edu pid:2864' WHERE (id = 10442 and (locked_at is null or locked_at < '2009-11-09 14:59:45') and (run_at <= '2009-11-09 18:59:45')) [0m [4;35;1mBand Load (1.5ms)[0m [0mSELECT * FROM "bands" WHERE ("bands"."id" = 34) LIMIT 1[0m [4;36;1mBand Update (0.6ms)[0m [0;1mUPDATE "bands" SET "updated_at" = '2009-11-09 18:59:45', "profile_background_image" = 'http://a3.twimg.com/profile_background_images/38193417/fbtile4.jpg', "url" = 'http://Coldplay.com', "screen_name" = 'coldplay' WHERE "id" = 34[0m [4;35;1mDelayed::Job Destroy (0.5ms)[0m [0mDELETE FROM "delayed_jobs" WHERE "id" = 10442[0m * [JOB] BandJob completed after 0.5448 1 jobs processed at 1.8011 j/s, 0 failed ... Thanks!

  Read the article

• BUG - ProteaAudio with Lua does not work

  - by Stackfan

  Any idea why i cant use or cant build in Lua the ProTeaAudio ? 1) Exist [root@example ~]# yum install lua-devel Loaded plugins: presto, refresh-packagekit Setting up Install Process Package lua-devel-5.1.4-4.fc12.i686 already installed and latest version Nothing to do 2) get failed to build the RtAudio [sun@example proteaAudio_src_090204]$ make g++ -O2 -Wall -DHAVE_GETTIMEOFDAY -D__LINUX_ALSA__ -Irtaudio -Irtaudio/include -I../lua/src -I../archive/baseCode/include -c rtaudio/RtAudio.cpp -o rtaudio/RtAudio.o rtaudio/RtAudio.cpp:365: error: no ‘unsigned int RtApi::getStreamSampleRate()’ member function declared in class ‘RtApi’ rtaudio/RtAudio.cpp: In member function ‘virtual bool RtApiAlsa::probeDeviceOpen(unsigned int, RtApi::StreamMode, unsigned int, unsigned int, unsigned int, RtAudioFormat, unsigned int*, RtAudio::StreamOptions*)’: rtaudio/RtAudio.cpp:5835: error: ‘RTAUDIO_SCHEDULE_REALTIME’ was not declared in this scope rtaudio/RtAudio.cpp:5837: error: ‘struct RtAudio::StreamOptions’ has no member named ‘priority’ make: *** [rtaudio/RtAudio.o] Error 1 [sun@example proteaAudio_src_090204]$ Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio > require("proAudioRt"); stdin:1: module 'proAudioRt' not found: no field package.preload['proAudioRt'] no file './proAudioRt.lua' no file '/usr/share/lua/5.1/proAudioRt.lua' no file '/usr/share/lua/5.1/proAudioRt/init.lua' no file '/usr/lib/lua/5.1/proAudioRt.lua' no file '/usr/lib/lua/5.1/proAudioRt/init.lua' no file './proAudioRt.so' no file '/usr/lib/lua/5.1/proAudioRt.so' no file '/usr/lib/lua/5.1/loadall.so' stack traceback: [C]: in function 'require' stdin:1: in main chunk [C]: ?

  Read the article

• Getting ellipses function parameters without an initial argument

  - by Tox1k

  So I've been making a custom parser for a scripting language, and I wanted to be able to pass only ellipses arguments. I don't need or want an initial variable, however Microsoft and C seem to want something else. FYI, see bottom for info. I've looked at the va_* definitions #define _crt_va_start(ap,v) ( ap = (va_list)_ADDRESSOF(v) + _INTSIZEOF(v) ) #define _crt_va_arg(ap,t) ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)) ) #define _crt_va_end(ap) ( ap = (va_list)0 ) and the part I don't want is the v in va_start. As a little background I'm competent in goasm and I know how the stack works so I know what's happening here. I was wondering if there is a way to get the function stack base without having to use inline assembly. Ideas I've had: #define im_va_start(ap) (__asm { mov [ap], ebp }) and etc... but really I feel like that's messy and I'm doing it wrong. struct function_table { const char* fname; (void)(*fptr)(...); unsigned char maxArgs; }; function_table mytable[] = { { "MessageBox", &tMessageBoxA, 4 } }; ... some function that sorts through a const char* passed to it to find the matching function in mytable and calls tMessageBoxA with the params. Also, the maxArgs argument is just so I can check that a valid number of parameters is being sent. I have personal reasons for not wanting to send it in the function, but in the meantime we can just say it's because I'm curious. This is just an example; custom libraries are what I would be implementing so it wouldn't just be calling WinAPI stuff. void tMessageBoxA(...) { // stuff to load args passed MessageBoxA(arg1, arg2, arg3, arg4); } I'm using the __cdecl calling convention and I've looked up ways to reliably get a pointer to the base of the stack (not the top) but I can't seem to find any. Also, I'm not worried about function security or typechecking.

  Read the article

• MSVC 2003 doesn't see any definitions from a nested include file

  - by ezpresso

  I have a piece of code with COM class declaration as follows: #include "PathTypes.h" MIDL_INTERFACE("552C7555-0555-4444-BA86-56CF39AAFFFF") IPathCalc : public IUnknown { virtual HRESULT STDMETHODCALLTYPE GetLocation( /* [retval][out] */ GeoLocation* pLoc) = 0; virtual HRESULT STDMETHODCALLTYPE SetLocation( /* [in] */ GeoLocation* pLoc) = 0; ... }; Below is the contents of PathTypes.h file: #if !defined(PATHCALC_TYPES_INCLUDED) #define PATHCALC_TYPES_INCLUDED #include "libastro/AstronomyStructs.h" #endif And the libastro/AstronomyStructs.h from an external cross-platform library: #ifndef _ASTRONOMY_STRUCTS_INCLUDED #define _ASTRONOMY_STRUCTS_INCLUDED typedef struct { double lattitude; double longitude; } GeoLocation; ... #endif /* _ASTRONOMY_STRUCTS_INCLUDED */ When I'm trying to build this code with g++ everything goes well. That's not the case with MSVC 2003 which returns error C2061: syntax error : identifier 'GeoLocation'. Seems like MSVC doesn't "see" the definitions from the libastro/AstronomyStructs.h file. When I replace #include "PathTypes.h" with #include "libastro/AstronomyStructs.h" the code compiles without errors. How to make MSVC 2003 to actually "see" the definitions from the nested include files?

  Read the article

• Is memory allocation in linux non-blocking?

  - by Mark

  I am curious to know if the allocating memory using a default new operator is a non-blocking operation. e.g. struct Node { int a,b; }; ... Node foo = new Node(); If multiple threads tried to create a new Node and if one of them was suspended by the OS in the middle of allocation, would it block other threads from making progress? The reason why I ask is because I had a concurrent data structure that created new nodes. I then modified the algorithm to recycle the nodes. The throughput performance of the two algorithms was virtually identical on a 24 core machine. However, I then created an interference program that ran on all the system cores in order to create as much OS pre-emption as possible. The throughput performance of the algorithm that created new nodes decreased by a factor of 5 relative the the algorithm that recycled nodes. I'm curious to know why this would occur. Thanks. *Edit : pointing me to the code for the c++ memory allocator for linux would be helpful as well. I tried looking before posting this question, but had trouble finding it.

  Read the article

• Output problem in mysql query in MFC program

  - by D.Gaughan

  Im currently working on a small MFC program that outputs data from a mysql database. I can get output when im using an sql statement that does not contain any variable eg. select album from Artists; but when i try to use a variable the program compiles but i get no output eg. mysql_perform_query(conn,select album from Artists where artists = '"+m_search_edit"'") Here is the function for mysql_perform_query: MYSQL_RES* mysql_perform_query(MYSQL *conn, const char* query) { // send the query to the database if (mysql_query(conn, query)) { // printf("MySQL query error : %s\n", mysql_error(conn)); // exit(1); } return mysql_use_result(conn); } And here is the code block for outputting the data: struct connection_details mysqlD; mysqlD.server = "www.freesqldatabase.com"; // where the mysql database is mysqlD.user = "**********"; // the root user of mysql mysqlD.password = "***********"; // the password of the root user in mysql mysqlD.database = "***************"; // the databse to pick // connect to the mysql database conn = mysql_connection_setup(mysqlD); CStringA query; query.Format("select album from Artists where artist = '%s'", CT2CA(m_search_edit)); res = mysql_perform_query(conn, query); //res = mysql_perform_query (conn, "select distinct artist from Artists"); while((row = mysql_fetch_row(res)) != NULL){ CString str; UpdateData(); str = ("%s\n", row[0]); UpdateData(FALSE); m_list_control.AddString(str); } The m_search_edit variable is the variable for an edit box. I am using Visual Studio 2008 with one copy of this program unicode and one nonunicode, I also have a version built with VC++ 6. Any tips on how I can get output from the databse using the m_search_edit variable??

  Read the article

• Casting Type array to Generic array?

  - by George R

  The short version of the question - why can't I do this? I'm restricted to .NET 3.5. T[] genericArray; // Obviously T should be float! genericArray = new T[3]{ 1.0f, 2.0f, 0.0f }; // Can't do this either, why the hell not genericArray = new float[3]{ 1.0f, 2.0f, 0.0f }; Longer version - I'm working with the Unity engine here, although that's not important. What is - I'm trying to throw conversion between its fixed Vector2 (2 floats) and Vector3 (3 floats) and my generic Vector< class. I can't cast types directly to a generic array. using UnityEngine; public struct Vector { private readonly T[] _axes; #region Constructors public Vector(int axisCount) { this._axes = new T[axisCount]; } public Vector(T x, T y) { this._axes = new T[2] { x, y }; } public Vector(T x, T y, T z) { this._axes = new T[3]{x, y, z}; } public Vector(Vector2 vector2) { // This doesn't work this._axes = new T[2] { vector2.x, vector2.y }; } public Vector(Vector3 vector3) { // Nor does this this._axes = new T[3] { vector3.x, vector3.y, vector3.z }; } #endregion #region Properties public T this[int i] { get { return _axes[i]; } set { _axes[i] = value; } } public T X { get { return _axes[0];} set { _axes[0] = value; } } public T Y { get { return _axes[1]; } set { _axes[1] = value; } } public T Z { get { return this._axes.Length (Vector2 vector2) { Vector vector = new Vector(vector2); return vector; } public static explicit operator Vector(Vector3 vector3) { Vector vector = new Vector(vector3); return vector; } #endregion }

  Read the article

< Previous Page | 84 85 86 87 88 89 90 91 92 93 94 95  | Next Page >