Recent questions tagged C++

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c++ - std::istream_iterator<> with copy_n() and friends

The snippet below reads three integers from std::cin; it writes two into numbers and discards the third: std::vector ... a question of its own. 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::thread - "terminate called without an active exception", don't want to 'join' it

As per This Question, I'm using a thread to terminate a function on user input. My code looks something like: ... it isn't necessarily). 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++ - Under what circumstances is it advantageous to give an implementation of a pure virtual function?

In C++, it is legal to give an implementation of a pure virtual function: class C { public: virtual int ... comment why this should be faster. 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 resize an image to a specific size in OpenCV?

IplImage* img = cvLoadImage("something.jpg"); IplImage* src = cvLoadImage("src.jpg"); cvSub(src, img, img); But ... resize it to the img size? 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++ - Handling overflow when casting doubles to integers in C

Today, I noticed that when I cast a double that is greater than the maximum possible integer to an integer, I ... the cast the best 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++ - Inserting a variadic argument list into a vector?

Forgive me if this has been answered already, as I couldn't find it... Basically I have an object that ... :vector<GenericNode*> inputs_; }; 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 'auto func(int)' before deduction of 'auto' in C++14

I have compiled following program in GCC using C++14. #include <iostream> using namespace std; auto func(int i); ... , what am I missing 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++ - Move the string out of a std::ostringstream

If I construct a string made of a list of space separated floating point values using std::ostringstream: std ... copying the entire content? 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++ - `static constexpr` function called in a constant expression is...an error?

I have the following code: class MyClass { static constexpr bool foo() { return true; } void bar() noexcept(foo ... , inside the class or out. 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 create constexpr std::vector

I can create constexpr std::array: constexpr std::array<int,5> values {1,2,3,4,5}; It works fine. But I cannot create ... > vec = {1,2,3,4,5}; 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++ - Meaning of default initialization changed in C++11?

C++2003 8.5/5 says: To default-initialize an object of type T means: - if T is a non-POD ... preserves the expected behavior. Citations welcome. 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 control memory allocation strategy in third party library code?

Previous header: "Must I replace global operators new and delete to change memory allocation strategy in third ... Please share your 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++ - How-to ensure that compiler optimizations don't introduce a security risk?

I have to write a Windows service that handles at some point confidential data (such as PIN codes, passwords, and ... won't be optimized-out ? 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 extra bits in a bool makes it true and false at the same time

If I get a bool variable and set its second bit to 1, then variable evaluates to true and false at ... = 1; end function return_true 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 the default constructor of std::pair<> set basic types (int, etc) to zero?

After writing: std::pair<int, int> x; Am I guaranteed that x.first and x.second are both zero? Or could ... NULL)? Or is the behavior undefined? 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 wrap a function with variable length arguments?

I am looking to do this in C/C++. I came across Variable Length Arguments but this suggests a solution with ... Any point where did I miss?? 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++ ld: symbol(s) not found for architecture x86_64

I'm trying to compile the Sam Hare's Struck code. I'm using mac OSX10.9, opencv 2.4.6 and Eigen 2.0. ... v to see invocation) Any ideas? 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++ - Why are std::shuffle methods being deprecated in C++14?

According to the cppreference.com reference site on std::shufle, the following method is being deprecated in c++ ... kind of alternative added? 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++ - Do I need to put constexpr after else-if?

Inspired by this answer, I tried to copy and paste (and add testing in main()) this code: template<typename T> std: ... ? I am using GCC 7.3. 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++ - How to implement an easy_bind() that automagically inserts implied placeholders?

I recently found this nifty snippet on the web - it allows you to bind without having to pass in explicit ... useful in generic TMP 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++ back end call the python level defined callbacks with swig wrapper

I am wrapping a library which was written in C++ to Python API libwebqq There is a type which is defined in ... and a solution to this 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++ - constexpr initialization of array to sort contents

This is a bit of a puzzle rather than a real-world problem, but I've gotten into a situation where I ... zeroes" problem instead of sorting.) 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 this macro be converted to a function?

While refactoring code and ridding myself of all those #defines that we're now taught to hate, I came across this ... I pasted it 'as is'. 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 rvalue reference vs const reference

This may be obvious but I think it is something difficult to me. Given this: void test(std::string&&) { } ... ? If no, are there differences? 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 boost::asio thread pool for general purpose tasks

In this blog I found a pretty neat example on how to create a simple thread pool using boost::asio. I ... implementations that are also as neat? 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 properly setup googleTest on OS X aside from XCode

How do I setup gTest, so that I can link aganist the library? I will code in vim, so I just ... mainroutine, the explicit -lgtest_main flag. 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++ - Common Uses For Pointers?

I'm a programming student with two classes in C#, but I'm just taking my first class in C++, and ... applications for pointers, so 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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609 views

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c++ - double to string without scientific notation or trailing zeros, efficiently

This routine is called a zillion times to create large csv files full of numbers. Is there a more efficient way to ... decimal (123. => 123) } See Question&Answers more detail:os...

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

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