Recent questions tagged C++

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c++ - array decay to pointer and overload resolution

I want to be able to differentiate array from pointers in overload resolution : class string { public: string(const ... if a better way exist 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 convert a byte array into double in C?

I've got a byte array containing 8 bytes and would like to convert and use them as a double precision binary ... tell me how to convert 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++ - Undocumented GCC Extension: VLA in struct

While reading the Clang documentation, I came across the following intriguing tidbit: [1] clang does not support the ... . Thanks for the help! 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 you mark a struct template as friend?

I have code like this: template <typename T, typename U> struct MyStruct { T aType; U anotherType; }; ... give friendship to the template ? 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 I use the result of a C++17 captureless lambda constexpr conversion operator as a function pointer template non-type argument?

While answering How do I write a lambda expression that looks like a method?, I tried to turn a captureless lambda ... question is, who's right? 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++ - Code runs 6 times slower with 2 threads than with 1

Original Problem: So I have written some code to experiment with threads and do some testing. The code should create ... 2 Threads: 0.35 seconds 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 C4250 VC++ warning mean?

What does C4250 Visual C+ warning mean in practical terms? I've read the linked MSDN page, but I still don't ... arise if I ignore the warning? 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 constructor in a class template - how to explicitly specify template argument for the 2nd parameter?

Template constructor in a class template - how to explicitly specify template argument for the 2nd parameter? compile ... again return 0; } 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 the main function work with no return value?

This question is out of curiosity; while writing a main for a test program, I returned nothing from main(no ... the same for main function? 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 members representations

I'm trying to make some callbacks from member functions and everything was ok until I tried to use a ... is the difference between them? 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++ - Calling constructor with braces

Simple question about C++11 syntaxis. There is a sample code (reduced one from source) struct Wanderer { explicit ... 's the thing is 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++ - Does calling a destructor explicitly destroy an object completely?

If I call a destructor explicitly ( myObject.~Object() ) does this assure me that the object will be ... as an important optimization. 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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205 views

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c++ - How to get the address of the std::vector buffer start most elegantly?

I want to use std::vector for dynamically allocating memory. The scenario is: int neededLength = computeLength(); / ... way to achieve the same? 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++ - Add elements to a vector during range-based loop c++11

I have used the new range-based for loop provided by C++11 standard and I came up with the following ... come up with a segmentation fault. 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++ - Win32 - read from stdin with timeout

I'm trying to do something which I think should be simple: do a blocking read from standard input, but timing ... for the event with a timeout. See Question&Answers more detail:os...

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

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193 views

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c++ - How can I find the size of all files located inside a folder?

Is there any API in c++ for getting the size of a specified folder? If not, how can I get the ... folder including all subfolders and files? See Question&Answers more detail:os...

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

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386 views

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c++ - Does GDI+ have standard image encoder CLSIDs?

The GDI+ Image::Save method requires a CLSID parameter to specify the encoder to use. The documentation points ... Microsoft's include files. 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 (i|o)fstream take a const char* parameter for a file name?

Why does the constructor and open method of the std::(i|o)fstream classes take the name of a file as a ... they wrote a class to replace. 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 the sequence-operation algorithms predicates are passed by copy?

I'm wondering why functors are passed by copy to the algorithm functions: template <typename T> struct summatory ... the pass-by-reference 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++ - Why isn't operator overloading for pointers allowed to work?

As per the comment under this answer, references were introduced primarily to support operator overloading which quotes ... used in its place. See Question&Answers more detail:os...

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

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102 views

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c++ - i++ less efficient than ++i, how to show this?

I am trying to show by example that the prefix increment is more efficient than the postfix increment. In ... better example to show 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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150 views

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c++ - Different sizeof results

Why does n not equal to 8 in the following function? void foo(char cvalue[8]) { int n = sizeof (cvalue); } But ... ]; int n = sizeof (cvalue); } 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++ - Forward Declaration of variables/classes in std namespace

I usually use forward declaration predominantly, if I have a class that does not need complete definition in .hpp ... does it have side effects? See Question&Answers more detail:os...

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

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240 views

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c++ - Are dollar-signs allowed in identifiers in C++03?

What does the C++ standard say about using dollar signs in identifiers, such as Hello$World? Are they legal? 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++ - Lambdas and capture by reference local variables : Accessing after the scope

I am passing my local-variables by reference to two lambda. I call these lambdas outside of the function scope. Is ... would expect output 2 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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162 views

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c++ - Get path to My Documents

From Visual C++, how do I get the path to the current user's My Documents folder? Edit: I have this: TCHAR ... thoughts as to why this might be? See Question&Answers more detail:os...

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

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372 views

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c++ - Set the digits after decimal point

I have a float number for example 12.12123 Is there a function which would display only number with 2 digits after ... it does not seem to help. See Question&Answers more detail:os...

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

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306 views

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c++ - Why do I need to include both the iostream and fstream headers to open a file

#include <iostream> #include <fstream> using namespace std; int main () { ofstream myfile; myfile.open ("test. ... needed to make it compile? See Question&Answers more detail:os...

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

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