Recent questions tagged C++

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c++ - Building mongo-cxx-driver using CMake ExternalProject_Add

I am trying to build mongo-cxx-driver in a CMake based project. This project is supposed to build on Windows, ... out where it is installed. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - hana::second can't deduce type

I'm trying to access a hana::type from a pair using hana::second... namespace hana = boost::hana; ... the contained hana::type as expected? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - checking for equality between an int and float in C

I came across this piece of code : int x=3; float y=3.0; if(x==y) printf("x and y are equal" ... . Someone please explain how is this happening. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why static_assert in template gives me different result with equivalent expressions?

I've noticed strange behavior of static_assert: #include <iostream> template <typename T, unsigned int D> struct Vec ... case gcc is correct? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - check if value exists in all indexes of array

So i have an array (size 5) of characters, each index containing a character, and i'm getting user input of ... condition 200 times. Any ideas? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Passing an array by reference to thread

I have an array that needs to be passed to multiple threads to be worked on. The array size is know ... when calling the function directly? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - VS 2008 - Link against older C runtime

How can I compile using Visual C++ 2008 and link against an older version of the C runtime (I want version 7 instead of 9)? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to enable c++20 in Visual Studio 2019 (16.3 preview 4)

How to enable c++20 in Visual Studio 2019 (16.3 preview 4)? I'm interesting to test some C++20 features. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Argument evaluation order between chained static function calls

I am curious why there is a difference in the argument evaluation order between chained static functions and member ... interesting is going on. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - GCC debugger stack trace displays wrong file name and line number

I am trying to port a fairly large C++ project to using g++ 4.0 on Mac OS X. My project compiles without ... not still not sure how to proceed. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why using namespace std is necessary here?

#include <iostream> using namespace std; int main() { cout << "!!!Hello World!!!" << endl; // prints ! ... build will fail. Why is it necessary? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Can't get past "undefined reference to `XXXX'"

I'm currently writing a header-only wrapper library which is supposed to provide C++ access to some FORTRAN code. ... out! :) EDIT: fixed typos See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - undefined reference to `shm_open' using CMake

I am using CMake under Ubuntu 14.04 to configure my project. I need to use a 3rd party library (say stuff. ... see my CMakeLists.txt. Thank you. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Add+Mul become slower with Intrinsics - where am I wrong?

Having this array: alignas(16) double c[voiceSize][blockSize]; This is the function I'm trying to optimize: ... } Why? Is _mm_setr_pd expensive? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Resolving a linker error: undefined reference to static class members

My code is Arduinoish. I turned on verbose compiling so I could verify that all the .o files are indeed ... is the compiled AVR library. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Combine multiple DLL's into 1

I'm wondering if it's possible to combine multiple DLL's into 1. I'm currently working on a C++ project that is ... if so, how would I do that? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - cout print hex instead of decimal

has it occurred to anyone that a simple std::cout might print a value in hex format when it is supposed to ... ).size()) any hints? thanks See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Deleting textures in opengl

Do I have to delete all the textures I created (using glDeleteTextures) before the program exists, or does ... delete the textures by himself? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - "Unpack" an array to call a function with variadic template

I'm using the ben strasser C++ fast csv parser: https://github.com/ben-strasser/fast-cpp-csv-parser. ... modifications to the fast csv parser. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Why the compiler complains that std::thread arguments must be invocable after conversion to rvalues?

Why the compiler complains if the the thread function delaration is changed to void thr(std::shared_ptr<Base>& ... the last one deleted Derived See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Computation of Cpu percentage by a single process in unix by the "top" command

I would like to know how does the "top" command compute the cpu percentage used by any process. I have tried ... be done. Thanks in advance. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - How to install METIS on ubuntu

I want to install the METIS package on ubuntu. I tried the instructions on the install.txt file which says ... me with the installation process? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Qt for iOS: code signing is required

I have yes smite version installed on my MaC and also Xcode version is 6.1. I downloaded Qt from official ... do build my applications on qt? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Delay execution 1 second

So I am trying to program a simple tick-based game. I write in C++ on a linux machine. The code below ... ); } Same result here. Anybody? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Import std lib as modules with clang

I am experimenting with modules in clang, and would like to include the standard lib as modules instead of ... also mentions std.core. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - What are the dangers of uninitialised variables?

In a program I am writing I currently have several uninitialised variables in my .h files, all of which ... I overlooking something? Thanks. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - bitwise shift promotes unsigned char to int

The following code: unsigned char result; result = (result << 4 ); Compiled with gcc version 4.6.4 (Debian ... value [-Wconversion] Why is that? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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c++ - Is there a reason on not allowing lambdas to deduce the return type if it contains more than one statement?

Taken from the C++0x FDIS (n3290): If a lambda-expression does not include a lambda-declarator, it is as if ... standard says so" answers. :) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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