c++

how to open many files simultaneously for reading in c

I'm trying to port some of my c++ code into c. I have the following construct class reader{ private: FILE *fp; alot_of_data data;//updated by read_until() method public: reader(const char*filename) read_until(some conditional dependent on the contents of the file, and the arg supplied) } Im then instantiating hundreds of these obj...

Qt -how to know whether content in child widgets has been changed?

In QMainWindow I have 2 QSplitters. In that splitters I have QTextEdit, QLineEdits, QTableWinget, Ragio buttons and so on... I want to know if somthing has been chaged after pressing File->New menu button. Is there any general method for doing this? Somwhere I have read that it is recomended to use isWindowModified() function of QMainWi...

Unable to load libsctp.so for non root user

I have a Linux application that uses the libsctp.so library. When I run it as root, it runs fine. But when I run it as an ordinary user, it gives the following error: error while loading shared libraries: libsctp.so.1: cannot open shared object file: No such file or directory But, when I do ldd as ordinary user, it is able to see...

private destructor for singleton class

Is it compulsory to have a private destructor for a singleton class. ...

Accessing subclass members from a superclass pointer C++

I have an array of custom class Student objects. CourseStudent and ResearchStudent both inherit from Student, and all the instances of Student are one or the other of these. I have a function to go through the array, determine the subtype of each Student, then call subtype-specific member functions on them. The problem is, because thes...

How are arrays passed?

Are arrays passed by default by ref or value? Thanks. ...

Having Public properties in c++ class

How do I have properties in C++ class, as you have in a C# class. I don't want to have getter and setter methods. ...

Determining line orientation using vertex shaders

Hi, I want to be able to calculate the direction of a line to eye coordinates and store this value for every pixel on the line using a vertex and fragment shader. My idea was to calculate the direction gradient using atan2(Gy/Gx) after a modelview tranformation for each pair of vertices then quantize this value as a color intensity to pa...

Create an instance of an exported C++ class from Delphi

I followed an excellent article by Rudy Velthuis about using C++ classes in DLL's. Everything was golden, except that I need access to some classes that do not have corresponding factories in the C++ DLL. How can I construct an instance of a class in the DLL? The classes in question are defined as class __declspec(dllexport) exampleC...

Benchmarks used to test a C and C++ allocator?

Please kindly advise on benchmarks used to test a C and C++ allocator? Benchmarks satisfying any of the following aspects are considered: Speed Fragmentation Concurrency Thanks! ...

project organization between x86 and x64

I have a mixed language solution in VS2008. I would like to structure the bin such that I have bin\x86\Release and bin\x64\Release among the other options. I can do something like this if I have all C# or all C++, but as the platform names don't overlap (x86 vs. Win32) between C++ and C#, I can't seem to do this with the macros (an...

openssl crypto library - base64 conversion

I'm using openssl BIO objects to convert a binary string into a base64 string. The code is as follows: void ToBase64(std::string & s_in) { BIO * b_s = BIO_new( BIO_s_mem() ); BIO * b64_f = BIO_new( BIO_f_base64() ); b_s = BIO_push( b64_f , b_s); std::cout << "IN::" << s_in.length(); BIO_write(b_s, s_in.c_str(), s_i...

Returning an array of tm* structs from a function

Hi Guys, Im trying to create an array of tm* structs, and then return them at the end of the function. This is what i have at the moment: struct tm* BusinessLogicLayer::GetNoResponceTime() { struct tm* time_v[3]; struct tm* time_save; int s = 3; time_save = LastSavedTime(); time_v[0] = time_save; sleep(5); time_s...

in free(): error: junk pointer, too high to make sense Segmentation fault: 11 (core dumped) gprof

I am trying to profile my application. For this I compiled my code with -pg and -lc_p option, it compiled successfully During run time I am getting the following error. in free(): error: junk pointer, too high to make sense Segmentation fault: 11 (core dumped) Doing GDB gives error as. (gdb) b main Breakpoint 1 at 0x5124d4: (gdb) r w...

How to execute a function called many times, only once !

Hello, is there a way to execute a function that is called thousand of times only once ? I have a function that adds items in a container of sort, and there is code in there, that updates lists and other windows (GUI staff). So, if i have to add a million items (the number of which is impossible to tell, anyone could call the function ...

exposing subcontrols from the custom widget plugin in QT

I am using QT 4.3. I have created one custom widget plugin. I could be able to show it in the desiner tool box as well as use it on the form with no problem. This custom widget internally holds QGroupBox, QLabel, QTextEdit. Now I want to apply the styles to individual componets of this custom widget. I want to expose these internal ...

Compile batch file into an EXE file

I want to compile a batch file into an EXE file using C++. I can get through parsing the batch file and writing a new .cpp file. But I don't know how to compile the new .cpp file into an EXE file for the end user. OK, here's the thing, I am creating an application in DevC++ that will read in a batch file. Then, one by one parsing it usi...

Modern equivalent of BoundsChecker for Visual Studio 2008

In VS6 times there was BoundsChecker from Numega. I understand it is dead now, please correct me if I am wrong. What are the reliable alternatives? Preferably free or at least with trial version available. ...

Reference to a pointer question

Please refer to the code below. In this code i am storing the const char* returned by test.c_str() into a reference. My question is Will the data be correctly refering to the contents of test. I am thinking that ptr returned by test.c_str() will be a temporary and if i bound it to a reference that reference will not be valid. Is my think...

Am I abusing Policies?

I find myself using policies a lot in my code and usually I'm very happy with that. But from time to time I find myself confronted with using that pattern in situations where the Policies are selected and runtime and I have developed habbits to work around such situations. Usually I start with something like that: class DrawArrays { pro...