Recent questions tagged C++

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c++ - `filesystem` with c++17 doesn't work on my mac os x high sierra

I'm following this tutorial: http://www.bfilipek.com/2017/08/cpp17-details-filesystem.html to checkout new c++ ... of string.h. Any thoughts? 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++ - Accessing map value by index

If I have a structure like std::map<string, int> myMap; myMap["banana"] = 1; myMap["apple"] = 1; ... hugely inefficient? Is there a better 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++ - Virtual Inheritance: Error: no unique final overrider

I know virtual inheritance is covered here before and before asking this question, I went through the detail of the virtual ... g++ 4.6.3. 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 using a vector of boolean values slower than a dynamic bitset?

Is using a vector of boolean values slower than a dynamic bitset? I just heard about boost's dynamic ... vector of boolean values instead? 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++ - calculating factorial using template meta-programming

I do not understand how this piece of code (from Wikipedia) works: template <int N> struct Factorial { enum { ... was I missing out on? Thanks! 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++ - Setting thread priority in Linux with Boost

The Boost Libraries don't seem to have a device for setting a thread's priority. Would this be the ... alot of Linux programming experience. 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 undefined behavior worth it?

Many bad things happened and continue to happen (or not, who knows, anything can happen) due to ... time without considerable overhead? 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 the use of "delete this"?

Today, I have seen some legacy code. In the destructor there is a statement like "delete this". I ... situations for using such statements? 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 rebasing DLLs (or providing an appropriate default load address) worth the trouble?

Rebasing a DLL means to fix up the DLL such, that it's preferred load adress is the load address that ... Chapter 20, DLL Advanced Techniques. 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++ - vector <unsigned char> vs string for binary data

Which is a better c++ container for holding and accessing binary data? std::vector<unsigned char> or std::string ... one a more 'correct' usage? 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++ - execv() and const-ness

I often use the execv() function in C++, but if some of the arguments are in C++ strings, it annoys me ... Does anyone know the reason for 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++ - Pointers to elements of std::vector and std::list

I'm having a std::vector with elements of some class ClassA. Additionally I want to create an index using a ... :list instead of std::vector? 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++ - C++11: What happens if you don't call join() for std::thread

Given below: void test() { std::chrono::seconds dura( 20 ); std::this_thread::sleep_for( dura ); } int ... of timeout behavior on the thread? 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++ - template class member function only specialization

I am reading the Complete Guide on Templates and it says the following: Where it is talking about class ... ? Can someone please clarify? 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 I find the 'temp' directory in Linux?

How do I find the 'temp' directory in Linux? I am writing a platform neutral C++ function that returns the temp directory. ... --------------- 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++ - GCC: Difference between -O3 and -Os

I am quite familiar with GCC -O3 flag, but how it differs from -Os, in which situation we should prefer one over 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++ - How to use C++20's likely/unlikely attribute in if-else statement

This question is about C++20's [[likely]]/[[unlikely]] feature, not compiler-defined macros. This documents ... in an if-else 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++ - Which sorting algorithm is used by STL's list::sort()?

I have a list of random integers. I'm wondering which algorithm is used by the list::sort() method. E. ... See also this more specific 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++ - G++ error:/usr/lib/rpm/redhat/redhat-hardened-cc1: No such file or directory

I'm studying qt on platform Fedora linux, It threw a g++ error as below while I make a sample cpp g++ ... indicate how to do for me please? 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 call function after window is shown?

Using Qt I create a QMainWindow and want to call a function AFTER the windows is shown. When I call the ... called before the window is shown. 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++ - Making QLabel behave like a hyperlink

how can I make a QLabel to behave like a link? What I mean is that I'd like to be able to click on ... this would invoke some command on it. 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 I convert boost::posix_time::ptime to time_t?

Is there some "standard" way or the best I can do is to compute it directly by subtracting from gregorian::date(1970,1,1)? 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::max - expected an identifier

I'm having a problem with std::max. I can't figure it out. int border = 35; int myInt = 2; int myOtherInt ... error : '::' What is wrong? 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++ - STL deque accessing by index is O(1)?

I've read that accessing elements by position index can be done in constant time in a STL deque. As far ... common implementation for a deque? 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++ - Are mutex lock functions sufficient without volatile?

A coworker and I write software for a variety of platforms running on x86, x64, Itanium, PowerPC, and ... it invulnerable to caching issues? 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++ - Does dereferencing a pointer make a copy of it?

Does dereferencing a pointer and passing that to a function which takes its argument by reference create a copy of the object? 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++ - Does std::array<> guarantee allocation on the stack only?

Is std::array<int,10> (without myself using new) guaranteed to be allocated in the stack rather then the ... use new inside its implementation. 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 this error mean: "error: expected specifier-qualifier-list before 'type_name'"?

I've been working on the Cell processor and I'm trying to create a struct that will hold an ... uintptr32_t args; } PTHREAD_BLOCK; See Question&Answers more detail:os...

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

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