Recent questions tagged C++

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c++ - Viewing a dynamically-allocated array with the Xcode debugger?

Let's say I have an array in C++: double* velocity = new double[100]; Using the GDB command line, I can ... as such. Anyone know what it is? 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++ - filling contours with opencv python

I have binary image with polylines created with: cv2.polylines(binaryImage,contours,1, (255,255,255)) What I ... . Please share your thoughts.. 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++ - Concatenating/Merging/Joining two AVL trees

Assume that I have two AVL trees and that each element from the first tree is smaller then any element from ... haven't found anything useful. 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 synchronizing with `std::mutex` slower than with `std::atomic(memory_order_seq_cst)`?

The main reason for using atomics over mutexes, is that mutexes are expensive but with the default memory model ... is very little contention. 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++ - std::mem_fun vs std::mem_fn

What is the difference between std::mem_fun and std::mem_fn? Why is the naming so confusing? Boost's documentation ... still use std::mem_fun? 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 can I detect if a type can be streamed to an std::ostream?

I'm trying to write a type trait to detect if a type has overloaded operator<<() suitable to use to an output ... /ikSBoT What am I doing wrong? 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 do I create and use a class arrow operator?

So, after researching everywhere for it, I cannot seem to find how to create a class arrow operator, i.e. ... I properly declare/prototype it? 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 use VC++ intrinsic functions w/o run-time library

I'm involved in one of those challenges where you try to produce the smallest possible binary, so I' ... : unresolved external symbol _memset 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++ - Definitions of sqrt, sin, cos, pow etc. in cmath

Are there any definitions of functions like sqrt(), sin(), cos(), tan(), log(), exp() (these from math.h ... wanted to know how do they work. 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 swap two numbers without using temp variables or arithmetic operations?

This equation swaps two numbers without a temporary variable, but uses arithmetic operations: a = (a+b) - (b=a) ... ? I was thinking about XOR. 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++ - memcpy vs for loop - What's the proper way to copy an array from a pointer?

I have a function foo(int[] nums) which I understand is essentially equivalent to foo(int* nums). Inside foo ... third option that I'm missing? 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++ - #ifdef DEBUG with CMake independent from platform

I am using CMake for building my projects on Windows (Visual Studio) as well as on Linux machines(gcc). I'd ... when the build type is Debug.) 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++ - Call to implicitly deleted copy constructor in LLVM

As per C++11 rules 6 things (default constructor, copy constructor, move constructor, copy assignment, move assignment ... deleted. why ? } 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's your convention for typedef'ing shared_ptr?

I'm flip-flopping between naming conventions for typedef'ing the boost::shared_ptr template. For example: typedef boost:: ... , would 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++ - Header file best practices for typedefs

I'm using shared_ptr and STL extensively in a project, and this is leading to over-long, error-prone ... add additional options for discussion. 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++ - Random Engine Differences

The C++11 standard specifies a number of different engines for random number generation: linear_congruential_engine, ... generally be preferred? 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 does the order of template argument substitution matter?

C++11 14.8.2 - Template Argument Deduction - [temp.deduct] 7 The substitution occurs in all types ... of template argument substitution matter? 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 get IP address of boost::asio::ip::tcp::socket?

I'm writing a server in C++ using Boost ASIO library. I'd like to get the string representation of client IP ... Does anyone know how to do it? 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 does everybody typedef over standard C types?

If you want to use Qt, you have to embrace quint8, quint16 and so forth. If you want to use GLib, you ... some kind of tradition for libraries? 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++ - OpenCV - Object matching using SURF descriptors and BruteForceMatcher

I have a question about objects matching with OpenCV. I'm useing SURF algorithm implemented in opencv 2.3 to first ... cv::waitKey(); return 0; 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 and why one would use Boost signals2?

Learning c++ and trying to get familiar with some patterns. The signals2 doc clearly has a vast array ... signals2::connection m_connection; }; 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++ - C: Where is union practically used?

I have a example with me where in which the alignment of a type is guaranteed, union max_align . I am ... practically, to explain my friend. 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 write vector values to a file

I have a large vector. The ways that I use multiply the run-time of the program hugely. The first is ... text file immediately with line breaks? 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++ - Cmake generator expressions

I'm trying for long time to understand the benefit of generator expressions such as $<xxx:yy> in CMake, ... examples. Many thank 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++ - gcc optimization flags for Xeon?

I'd want your input which gcc compiler flags to use when optimizing for Xeons? There's no 'xeon' in mtune or ... so which is the closest match? 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++ - Recursive Fibonacci

I'm having a hard time understanding why #include <iostream> using namespace std; int fib(int x) { if (x ... 1 shouldn't it eventually return? 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-4.9 Undefined Behavior Sanitizer

In gcc-4.9 changes it says: UndefinedBehaviorSanitizer (ubsan), a fast undefined behavior detector, has been added ... or what features it has? 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++ - Convert wchar_t to char

I was wondering is it safe to do so? wchar_t wide = /* something */; assert(wide >= 0 && wide < 256 ... wide char will fall within ASCII range. See Question&Answers more detail:os...

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

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