Recent questions tagged C++

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c++ - Are IEEE floats valid key types for std::map and std::set?

Background The requirement for a comparator on the key type of an associative container (for example std::map ... commitee member or something. 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 use std::stoul and std::stoull in Android?

C++11 has two new string conversion functions into unsigned long and long long: std::stoul() and std::stoll(). ... LOCAL_CPPFLAGS += -std=c++11 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++ - what is SDKDDKVer.h for?

All project created with MSVC have stdafx, which is precompiled headers, which I know what they are but what about ... . What is this for ? 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++ - Understanding GCC 5's _GLIBCXX_USE_CXX11_ABI or the new ABI

https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html I ran into crashing/valgrind issues with using std:: ... --a place to start. 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 any reason not to make a member function virtual?

Is there any real reason not to make a member function virtual in C++? Of course, there's always the ... member functions virtual by default? 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++ - Getting std::thread/mutex to work under Win7 with mingw and g++ 4.7.2

Greetings, I've recently moved out of my unix shelter to test a supposedly cross-platform networking library only to ... c++11 Sincerely, Chris. 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 overload a function that can tell a fixed array from a pointer?

Motivation: Almost for fun, I am trying to write a function overload that can tell apart whether the argument is a fixed ... arr" << std::endl;} 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++ - cmake find_package specify path

I have 2 versions of OpenCV installed on my machine. One is in /usr/local/opencv3.1. I presume the install ... for any help. Thank you. 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++ - Why am I not provided with a default copy constructor from a volatile?

This code: class X { int member; }; volatile X a; X b = a; Fails with the error: prog.cpp:6:7 ... generate a volatile copy constructor for me? 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++ - What's time complexity of this algorithm for finding all combinations?

Combinations Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example ... .pop_back(); } } }; 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++ - Performance degradation due to default initialisation of elements in standard containers

(Yes, I know there is a question with almost the same title, but the answer was not satisfactory, see below ... and this question for details). 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++ - This case of template function overloading eludes my understanding

#include <iostream> template<typename T> struct identity { typedef T type; }; template<typename T> void bar ... resolution is involved here? 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++ - Treat C cstyle array as std::array

Is there any safe and standard compliant way to treat a C style array as an std::array without copying the data ... to the existing data as one. 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++ - Clean up your #include statements?

How do you maintain the #include statements in your C or C++ project? It seems almost inevitable that ... like a somewhat universal problem. 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++ - Why does initializing an extern variable inside a function give an error?

This code compiles fine: extern int i = 10; void test() { std::cout << "Hi" << i << std::endl; } ... the same is allowed at a global scope? 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++ - Getting a buffer into a stringstream in hex representation:

If I had a buffer like: uint8_t buffer[32]; and it was filled up completely with values, how could I get ... great help to achieve this somehow. 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++ - Eclipse indexer can't resolve shared_ptr

After researching this on the internet, I've been unable to get the Eclipse indexer to resolve "shared_ptr" ... what's breaking the indexer? 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++ - what does `using std::swap` inside the body of a class method implementation mean?

I was trying to learn and adopt the copy-swap idiom following this thorough explanation on this question: the Copy- ... ? what does ADL mean ? 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++ - Cannot open include file: 'ctype.h': No such file or directory

I installed c++ package on VS 2015 , if I tried to build the project ,the following problem appears : C1083 ... 31 Any possible solution .... 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++ - Undefined symbols for architecture x86_64: Which architecture should I use?

I'm trying to do some really simple stuff in C++, but I can't find any information on how to tackle this. ... Mac but not using XCode, just gcc. 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++ - Why is std::iterator deprecated?

Template class std::iterator is set to be deprecated in C++17. Why so? It has been a handy way to make sure std:: ... way of doing it in C++17? 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++ - Multi-dimensional array initialization

I have seen a question in C++ exam today: Given the array int Multi[2][3][2] = {14,11,13,10,9, ... element with such indeces? It's so confusing. 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 observer_ptr

What exactly is the point of the construct std::observer_ptr in the library fundamentals technical specification ... self-documenting 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++ - How to disable #pragma warnings?

While developing a C++ application, I had to use a 3rd party library which produced a huge amount of warnings ... using the GNU C++ 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++ - Why does an object returned by value have the same address as the object inside the method?

#include <stdio.h> #include <array> #include <vector> std::vector<int> foo() { int i; std: ... 0x7ffee28d290c, 0x7ffee28d28f0, 0x7ff401402c00 $ 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++ - Unexpected end of file error

I hope you can help me, cause I have no idea about what's going on. I'm having the following error while ... #endif Sorry for so much code. 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++ - Avoiding unused variables warnings when using assert() in a Release build

Sometimes a local variable is used for the sole purpose of checking it in an assert(), like so - int Result = ... isn't an option either...). 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 begin() == end() for any empty() vector?

I have long assumed that for any empty std::vector V, V.begin() == V.end(). Yet I see nothing in ... happen to be true on most implementations? See Question&Answers more detail:os...

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

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