Recent questions tagged C++

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c++ - Get the points of intersection from 2 rectangles

Let say that we have two rectangles, defined with their bottom-left and top-right corners. For example: rect1 ... only if 2 rectangle intersect. 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 and order dependent linking of shared libraries

I have a few small components that I am building as shared libraries for my main application. Lets use an ... libraries for linking in CMake? 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 push_back is slower than operator[] for a previously allocated vector

I just read this blog http://lemire.me/blog/archives/2012/06/20/do-not-waste-time-with-stl-vectors/ comparing performance ... int (s1 + s2); } 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++ - Defining constructor in header file vs. implementation (.cpp) file

I can define the body of a class constructor in the class .h file or in the implementation file .cpp. These ... What is your opinion about this? 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++ - Columns auto-resize to size of QTableView

I am new to Qt and I have just managed to make a QTableView work with my model. It has fixed 3 columns. ... every the the window gets resized. 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 the use of .map files the linker produces?

What is the use of .map files VC++ linker produces when /MAP parameter or "Generate map file" project setting is ... how do I benefit from them? 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++ - Ubuntu - Linking boost.python - Fatal error: pyconfig cannot be found

Having some issues, now I have read the following: hello world python extension in c++ using boost? I have ... there's just a problem linking? 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++ - fatal error: mpi.h: No such file or directory #include <mpi.h>

when I compile my script with only #include <mpi.h> it tells me that there is no such file or directory. But ... . Anyone know how to fix this? 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++ and opencv get and set pixel color to Mat

I'm trying to set a new color value to some pixel into a cv::Mat image my code is below: Mat image = ... in the output image dont change. 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++ - Get time since epoch in milliseconds, preferably using C++11 chrono

All I want is to get the time since epoch in milliseconds and store it in an unsigned long. I found this ... want it to be platform independent. 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 no emplacement iterators in C++11 or C++14?

C++98 has front_inserter, back_inserter, and inserter, but there don't seem to be any emplacement versions of ... , back_emplacer, and emplacer? 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 the proper way to enable AddressSanitizer in CMake that works in Xcode

I've added AddressSanitizer flag as follow: set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address") Everything ... be much appreciated. 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++ - Should custom containers have free begin/end functions?

When creating a custom container class that plays by the usual rules (i.e. works with STL algorithms, works with ... ; or using std::begin;? 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++ - Proper way of casting pointer types

Considering the following code (and the fact that VirtualAlloc() returns a void*): BYTE* pbNext = reinterpret_cast< ... instead of the other? 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 do we need argc while there is always a null at the end of argv?

It seems that the argv[argc] is always NULL, so I think we can traverse the argument list without argc. A single ... , why do we need an argc? 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 Clang optimize away x * 1.0 but NOT x + 0.0?

Why does Clang optimize away the loop in this code #include <time.h> #include <stdio.h> static size_t const N ... answer is different for each.) 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 does Visual Studio do with a deleted pointer and why?

A C++ book I have been reading states that when a pointer is deleted using the delete operator the memory ... instead of some random address? 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 set initial size of std::vector?

I have a vector<CustomClass*> and I put a lot of items in the vector and I need fast access, so I don't ... to avoid copy when I insert new)? 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 is a variable's linkage and storage specifier?

When someone talks about a variables storage class specifier, what are they talking about? They also often talk about ... context, what 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++ - How does the centripetal Catmull–Rom spline work?

From this site, which seems to have the most detailed information about Catmull-Rom splines, it seems that four ... those input values give? 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 know that a triangle triple exists in our array?

I was stuck in solving the following interview practice question: I have to write a function: int triangle(int[] ... this problem. 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++ - Why use a perfectly forwarded value (a functor)?

C++11 (and C++14) introduces additional language constructs and improvements that target generic programming. These include ... f(std::get...? 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++ - Ndk-build: CreateProcess: make (e=87): The parameter is incorrect

I get an error when build static lib with NDK on Windows platform: process_begin: CreateProcess( "PATH"android-ndk- ... I can solve this issue? 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 use variadic arguments now when initializer lists are available?

I've been wondering what are the advantages of variadic arguments over initializer lists. Both offer the same ability ... in C as well? 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 is wrong with "checking for self-assignment" and what does it mean?

In Herb Sutter's book Exceptional C++ (1999), he has words in item 10's solution: "Exception-unsafe" ... , he explains about self-assignment. 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++ - Forcing GCC to compile .cpp file as C

I have an externally provided .cpp file. It is a mixture of C compatible code and a bit of C++ as well. ... it to remain as a pristine copy. 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++ - Does alignment really matter for performance in C++11?

Does alignment really matter for performance in C++11? There is an advice in Stroustrup's book to order the ... think about when writing code. 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++ - Get return type of member function without an object

I have a number of classes that I cannot modify. Each has a copy constructor, at least one other constructor, ... any way of avoiding this? See Question&Answers more detail:os...

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

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