Recent questions tagged C++

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c++ - localtime vs localtime_s and appropriate input arguments

time_t rawtime; struct tm * timeinfo; time ( &rawtime ); timeinfo = localtime ( &rawtime ); This returns: ... the whole localtime safety issue. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Arduino sprintf float not formatting

I have this arduino sketch, char temperature[10]; float temp = 10.55; sprintf(temperature,"%f F", temp); Serial. ... it to be a char string. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - std::dynarray vs std::vector

C++14 presents std::dynarray: std::dynarray is a sequence container that encapsulates arrays with a size that is ... (and also re-sizable)? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can a declaration affect the std namespace?

#include <iostream> #include <cmath> /* Intentionally incorrect abs() which seems to override std::abs() */ int abs( ... the use of std or what? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - When do I use fabs and when is it sufficient to use std::abs?

I assume that abs and fabs are behaving different when using math.h. But when I use just cmath and std::abs, ... fabs? Or isn't this defined? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Load an PEM encoded X.509 certificate into Windows CryptoAPI

I need to load a PEM encoded X.509 certificate into a Windows Crypto API context to use with C++. ... error" programming and getting nowhere. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Opengl: 2d HUD over 3D

I have looked at some questions posted here on the matter and still cant work out why my 2d HUD appears but ... turn cancels out the 3d space. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - std::copy to std::cout for std::pair

I have next code: #include <iostream> #include <algorithm> #include <map> #include <iterator> //namespace std //{ ... this problem do you know? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Erasing using backspace control character

I am trying to use the backspace control character '' to erase trailing commas at the end of line. Although it works ... 9. How do I do this ? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - "APIENTRY _tWinMain" and "WINAPI WinMain" difference

What are the difference from these 2 function?: int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, ... , int nCmdShow) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to sleep or pause a PThread in c on Linux

I am developing an application in which I do multithreading. One of my worker threads displays images on the ... achieve threads pause/suspend? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to tell if a lib was compiled with /mt or /md?

Given a compiled lib, is there a way to tell if it was compiled with /md or /mt just by looking at it ( ... that was optimized in such a way? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - is it possible to make function that will accept multiple data types for given argument?

Writing a function I must declare input and output data types like this: int my_function (int argument) {} Is it ... int bool char] argument) {} See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Forcing NVIDIA GPU programmatically in Optimus laptops

I'm programming a DirectX game, and when I run it on an Optimus laptop the Intel GPU is used, resulting in ... reported (the one in use). See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Specializing a template on a lambda in C++0x

I've written a traits class that lets me extract information about the arguments and type of a function or ... to accept a lambda expression? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to execute a piece of code only once?

I have an application which has several functions in it. Each function can be called many times based on ... efficient way of handling this. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Use of typename keyword with template function parameters

In C++, the typename keyword is needed so the compiler can disambiguate between nested types and nested values in ... one but not the other? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - std::map thread-safety

Is reference to object in std::map is thread safe? std::map< std::string, Object > _objects; map can be ... items to map? will it reallocate? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is the ranged based for loop beneficial to performance?

Reading various questions here on Stack Overflow about C++ iterators and performance**, I started wondering ... non-invalidating containers? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is "std::cout" usable in Android-ndk

In Android-ndk, we could use "__android_log_write", "__android_log_print", ... etc to output messages to ... equivalent to logging messages ? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Compile-time constant id

Given the following: template<typename T> class A { public: static const unsigned int ID = ?; }; I want ID ... the cases of a switch statement. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Check if one string is a prefix of another

I have two strings which I'd like to compare: String and String:. Is there a library function that would ... string is a prefix of another. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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247 views

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c++ - Disabling g++'s return-value optimisation

What flag(s) do I need on the command line to disable the return-value optimisation automatically enabled by the g++ compiler? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How do static variables in lambda function objects work?

Are static variables used in a lambda retained across calls of the function wherein the lambda is used? Or is ... would like a decent source. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is there a C++11 syntax file for vim?

In particular, the display of initialization lists is really bad: vector<int> v({1,2,3}); will highlight the ... in red (denoting an error). See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - gsl::not_null<T*> vs. std::reference_wrapper<T> vs. T&

C++ Core Guidelines has been presented recently (congrats!) and I am concerned about gsl::not_null type. As ... for this, I hope properly. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Which is faster: x<<1 or x<<10?

I don't want to optimize anything, I swear, I just want to ask this question out of curiosity. I know that on ... hate me for this question. :) See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Using emit vs calling a signal as if it's a regular function in Qt

Let's say I have this signal: signals: void progressNotification(int progress); I only recently learned about the ... it just syntactic sugar? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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