c++

C++ stdext hashmap efficiency - reorganising (?)

Hello, I have faced a quite strange thing related to stdext hashmap. I have to work with a lot of objects and it is a priority to access the elements in a fast way. My program read the object values from a file and if it's a new element, then insert this value in a hashmap, if it is an already processed object, then changes the stored ...

C++ code in header files

My personal style with C++ has always to put class declarations in an include file, and definitions in a .cpp file, very much like stipulated in Martin York's answer to C++ Header Files, Code Separation. Admittedly, part of the reason I like this style probably has to do with all the years I spent coding Modula-2 and Ada, both of which h...

How can I detect when an SD card is plugged in?

I'm writing a PC application in C++ that needs to detect when a user connects an SD card to his/her computer. I know how to detect when the card reader is connected, but I do not know how to detect when individual cards are connected/removed. Does Windows have an IO interface to detect arrival/removal of SD cards? [Update] the WM_DEVIC...

Have you ever read C++ standard paper

Whenever I follow C++ related IRC channels, I see folk giving each other C++ papers' standard's links to come to a decision on ongoing discussions, since they all boil down to standard, naturally. However, those papers are rather boring and hard to read. How do you manage to read those bloated papers? and Is reading those papers inevitab...

Linking classes in Geany

I am writing a CLI application for Linux in Geany (a C++ IDE). I want to link a simple config file reader class so it can be used in my program. Just including it doesn't work, I get undefined reference errors. I know how to do this in Dev-C++ on Windows, but not Geany. Thanks for helping! ...

How do I return hundreds of values from a C++ function?

In C++, whenever a function creates many (hundreds or thousands of) values, I used to have the caller pass an array that my function then fills with the output values: void computeValues(int input, std::vector<int>& output); So, the function will fill the vector output with the values it computes. But this is not really good C++ style...

Is there a beginner's book for C++ socket programming?

I'm fairly new to C++ sockets. Is there a book for beginners for C++ socket programming? for windows i really need help ive been through alot of tutorials dont get any of it and im using dev-C++ ...

Connecting to an mssql server from a remote machine gives Login failed for user ''

I get this error when I try to connect to a remote SQL server using this connection string. Error: ODBC error: 28000118452[Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user ''. The user is not associated with a trusted SQL Server connection. Connection string: "DRIVER={SQL Server};SERVER=testserver,...

Is it possible to get a valid token from a remote computer?

Is it possible to impersonate a u/p on a remote computer? Ideally I would like to call the ImpersonateLoggedOnUser with a token I would obtain from logging into a remote computer. I know I can make a valid connection using wnet functions, but just don't know about impersonation. ...

How do I build an import library (.lib) AND a DLL in Visual C++?

I want to have a single Visual Studio project that builds a DLL file and an import library (.lib) file. (An import library is a statically-linked library that takes care of loading that DLL file in other projects that use it). So I went to Visual Studio C++ 2008 Express Edition, created a New Project of type Class Library, and set the ...

Machine dependent _write failures with EINVAL error code

This has some lengthy background before the actual question, however, it bears some explaining to hopefully weed out some red herrings. Our application, developed in Microsoft Visual C++ (2005), uses a 3rd party library (whose source code we luckily happen to have) to export a compressed file used in another 3rd party application. The ...

C++ Library for modifying a ZIP file in place

I'm looking for a way to add or remove files to/from an existing ZIP archive, or any other archive format for that matter as long as there are cross platform APIs, without having to rewrite a new zip file with new files added to it, or sans items deleted from it. With ZIP files, the catalog is placed at the end of the file so that, an...

Different methods to use a class/struct - C++

struct Foo { void SayHello() { std::cout << "Hi, I am Foo"; } }; I have the above given struct. I have seen a usage like this in one of our code base. Foo foo; { foo.SayHello(); } IMO, It does same like Foo foo; foo.SayHello(); Or is there any advantage/difference for the first method? Any thoughts? ...

Are there alternatives to polymorphism in C++?

The CRTP is suggested in this question about dynamic polymorphism. However, this pattern is allegedly only useful for static polymorphism. The design I am looking at seems to be hampered speedwise by virtual function calls, as hinted at here. A speedup of even 2.5x would be fantastic. The classes in question are simple and can be cod...

How do I fix my while Error?

I'm writing a program in Microsoft Visual Studio with C++ that will retrieve information from a .txt file. In that file there are negative numbers, but when I try to write a while loop that states what to do if there is a negative number, I get several errors. Can someone please help me with this? Here is my code and I do realize th...

When is it appropriate to use C++ exceptions?

I'm trying to design a class that needs to dynamically allocate some memory.. I had planned to allocate the memory it needs during construction, but how do I handle failed memory allocations? Should I throw an exception? I read somewhere that exceptions should only be used for "exceptional" cases, and running out of memory doesn't seem ...

Gui toolkits, which should I use?

I am writing a fairly large and complex data analysis program and I have reached the point where I think it is about time to build a GUI for the program. So my question is: Which GUI toolkit should I use? I am completely new to coding and building GUIs and would appreciate any guidance that can be offered. It doesn't have to be the sim...

Guaranteed lifetime of temporary in C++?

Does C++ provide a guarantee for the lifetime of a temporary variable that is created within a function call but not used as a parameter? Here's an example class: class StringBuffer { public: StringBuffer(std::string & str) : m_str(str) { m_buffer.push_back(0); } ~StringBuffer() { m_str = &m_buffer[0...

dSYM Directories While Compiling C++ Code in MacOS

Hi, Why compiling C++ in Mac always create *.dSYM directories? Is there a way to disable that? ...

C++ best learning path: just utopia?

C++ is a great language (imho). But starting off with C++ as a completely new language to learn, which formative path would you suggest? Books, websites, anything that could speed up learning without trading in knowledge and understanding for memorization and confusion. A path indeed, which leads to C++ knowledge and understanding in ...