C++ - Страница 1252

I have this code, but I need help to use OpenMP #pragmas to increase its speed. I want to parallelize the for loops over variables i and j. The values of n and m can be much larger, too. For example, n = 1000, m = 500.

My code:
for (int i = 0; i...

(Note: This question is about not having to specify the number of elements and still allow nested types to be directly initialized.)
This question discusses the uses left for a C array like int arr ;. On his answer, @James Kanze shows one of the...

I'm confused about how scoping and memory persistence works with std::vectors. Consider the following:

#include #include class Entity { std::string name; } class MyClass { std::vector class_vec; MyClass() { std::vector local_vec(100); class_vec =...

Suppose I have 2 meshes and I used one VBO for each mesh. The vertex attributes (position, normal, color) are contained in a struct:

struct Vertex { glm::vec3 position; glm::vec3 normal; glm::vec3 color; } and they are interleaved in the VBO;...

As it is known, declaring extern C to C++ function makes its name have C linkage, enabling C code to link.

My question is - are there other programming languages we can make C++ function names have linkage to, something like extern Lisp or extern...

I have written a code to encrypt according to AES 256 algorithm and it works to give me an output file but I realised that it hangs after running the EncryptDecryptString function and does not perform anything else after that. Why is this so? How...

Consider a Base class and a derived class that inherits from it called Child. Assume the Base class has a member function declared virtual, and that Child overrides that function. I would like to declare a variable as a Base class object, initialize...

I'm having a problem with the RMB Context menus, In my main frame I have a grid control with the RMB context menu event. The shortcut keys appear correctly. See Copy for Ctrl + C,Paste for Ctrl + V, etc...

Then I have a dialog with already a...

I am trying to use a library (Intel TBB) in my R package on Windows, but not sure how to write makevars.win.

I have Rtools installed, and there are the library under include:

C:\RBuildTools\4.3\x86_64-w64-mingw32.static.posix\include\tbb

My...

I tried to use backtrace_symbols in a sianal handler, but now I know the function is not signal-safe.

And there is always the backtrace in android log when the crash happened, I want my program to be convenient like the backtrace in android...

I am trying to understand a C++ OpenGL project (github/XCSoar) using VSCode on a Debian Linux box (don't think that is significant, but...). I have noticed that the 'active/inactive' code block highlighting is wrong sometimes, and it really screws...

In general, (quiet) NAN times zero should give NAN -- and it does.

However, in one particular performance-critical part of my code, I want zero times anything to be zero.

What's a fast way to do this in C++?

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I have no issues reading file paths with ASCII characters but have issues reading file paths with Unicode characters. I have tried to ensure that the code is correctly encoded to support unicode characters but it still doesnt work. How do i read the...

I have a non-template class (Uart) and want to create template constructor. It needs to take another template class object (SafeQueue). Then this constructor will call another template function defined inside the class.

class signatures are given...

Compiling the following code gives the error message: type illegal.

int main() { // Compilation error - switch expression of type illegal switch(std::string( raj )) { case sda : } } You cannot use string in either switch or case. Why? Is there any...

I have a complex cc_test which has tons of args and envs specified in the rules:

cc_test( name= my_test , args= , env= {...tons of envs...}, ) Now I want to run it locally by running ./bazel-bin/my_test, so that I can use GDB to debug it.

The...

env: I use vscode ssh remote plug-in link ubuntu20.04(it run in orangepi3b, I don't know if that's the problem.) question:
1.1 when I ctrl + mouse leftclick, after clicking open() function is not into usr/include/fcntl.h function declaration, but...

Is there anything like boost::thread_group in C++11?

I'm just trying to port my program from using boost:thread to C++11 threads and wasn't able to find anything equivalent.

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How can I add values to graph nodes in c++?

int n,v,u; cin>>n>>q; vector g; for(int i=0; i>v>>u; v--,u--; g .pb(u); } I was solving a dfs problem and I got into this

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I working on my game engine with both support of Windows and Linux. And for Linux i added support for Xlib and XCB libraries that help me to create window and handling events in it. With Xlib all working good, but when i turn off vsync in XCB and...

If ShellExecute is called with the following parameters, no action is taken, and no errors are reported:

nResult = ShellExecute(nullptr, L open , strPptBuilderPath, strParameters, nullptr, SW_SHOWNORMAL); When strPptBuilderPath resembles...

Please let me know if my answers are good. I think I have an issue with the two while loops for number 2. I know how to do it in one while loop, but not two while loops for question 2.
Write C++ code to copy elements from an old queue to new queue...

I'm executing this function to push to a specific location of a vector a new pair of objects. But as soon the program tries to execute the push_back (emplace_back) function. The program gets stuck and I get it returns without any clear errors:...

In my code base there is code like the example below. A stringstream is used to collect output and later, if there have been things written to the stream these things are written to another stream. To check if there are things on the collecting...

I try to create a small app based on Vulkan v1.3.275.0 (and MoltenVK driver for macOS).

I successfully bundle my app into *.app with recommended Vulkan structure for macOS. My app opens a window using metal-cpp library and creates a Vulkan...