Recent questions tagged C++

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c++ - How should I handle "cast from ‘void*’ to ‘int’ loses precision" when compiling 32-bit code on 64-bit machine?

I have a package that compiles and works fine on a 32-bit machine. I am now trying to get it to compile ... these files to avoid these casts? 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++ - Rule of thumb for when passing by value is faster than passing by const reference?

Suppose I have a function that takes an argument of type T. It does not mutate it, so I have the choice of ... to be "very cheap to 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++ - C pointer arithmetic without object of structure

I think it is not possible in C but ask to verify this. Is it possible to make arithmetic between structure ... the case is interesting for me. 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 declare an __stdcall function pointer

I tried this typedef void (* __stdcall MessageHandler)(const Task*); This compiles but gives me this warning (VS2003 ... 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 to call std::min() when min has been defined as a macro?

How do I call std::min when min has already been defined as a macro? 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 tell valgrind to memcheck forked processes?

I have a process x that I want to check for leaks with valgrind. The problem is that x is run by y, and y ... linux and valgrind-2.4.0. 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++ - Why can const members be modified in a constructor?

I'm curious why const members can be modified in the constructor. Is there any standard rule in initialization that ... be an error 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++ - Calling a static method by repeating the object name?

I have a singleton: struct foo { static foo& instance() { static foo f; return f; } }; When re-arranging ... ::foo::instance() compiles. 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++ - Create string with specified number of characters

Is there a way to create a string of say 256 characters at initialization with c++? Part of my assignment ... like there is an easier way. 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++ - Valgrind reporting a segment overflow

When running my program with valgrind / callgrind I get the following message a lot: ==21734== brk segment ... valgrind, or of my program? 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 the gcc warning "project parameter passing for X changed in GCC 7.1" mean?

I have a C++ project that builds fine and without warnings with gcc 7.2 on x86 Linux and Windows, I needed to ... of what they mean.. any clue? 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++ - Avoiding implicit conversion in constructor. The 'explicit' keyword doesn't help here

I am able to avoid the implicit conversion of a constructor using the explicit keyword. So now, conversions like A a1 = ... a1.num; 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++ - Does new char actually guarantee aligned memory for a class type?

Is allocating a buffer via new char[sizeof(T)] guaranteed to allocate memory which is properly aligned for the type ... is an over-aligned type? 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++ - Redefining lambdas not allowed in C++11, why?

Example: #include <functional> int main() { auto test = []{}; test = []{}; return 0; } This ... to be omitted for lambdas generally. 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 point of const void?

Apparently, it is possible to declare a function returning const void: const void foo() { } g++ seems ... void have any practical significance? See Question&Answers more detail:os...

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

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252 views

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c++ - How to alphabetically sort strings?

I have been trying to use this c++ program to sort 5 names alphabetically: #include <iostream> #include < ... whats wrong with my program? 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 access variables in different class from other class?

Let just say that we have two classes, A and B. Here is code for both of them class A { public: int ... because of this line SubMenu.resize(3); See Question&Answers more detail:os...

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

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210 views

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c++ - USB Programming with Qt

Is there anyway I can do USB programming in Qt? I am using Qt Creator 2.6 which is based on Qt version 5.0 ... OS is windows 7 ultimate 32 bit. 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++ - Constructing and sending binary data over network

I am creating a command-line client for minecraft. There is a full spec on the protocol that can be found ... the modified UTF-8 yet though. See Question&Answers more detail:os...

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

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490 views

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c++ - How to Read the certificates file from the PKCS7.p7b certificate file using openssl?

I am getting PKCS7 file (p7b). I want to read the content of the file and extract certificate in X509 ... PKCS container using openssl library? 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 --gc-sections and finding symbol dependencies

I'm trying to reduce the size of my elf executable. I'm compiling with -ffunction-sections -fdata-sections and ... .ld Thanks for the help. See Question&Answers more detail:os...

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

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200 views

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c++ - Virtual inheritance doesn't break static composition?

I was working the last 5 years with the assumption that virtual inheritance breaks static composition. But now I ... instance. Is this right? 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++ - Calling function in injected DLL

I want to call a function in a remote process of an injected DLL that I've made. I have successfully injected ... crash. How can I solve 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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351 views

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c++ - cin.getline( ) with larger size

#include<iostream> using namespace std; int main() { char test[10]; char cont[10]; cin.getline(test,10); ... is empty. Could someone explain 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++ - Detect insertion of media into a drive using windows messages

I am currently using WM_DEVICECHANGE to be notified when new USB drives are connected to the computer. This works ... having to use polling? See Question&Answers more detail:os...

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

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183 views

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c++ - Recursive lambda callbacks without Y Combinator

I wish to create a callback that recursively returns itself as a callback. The suggested method to recurse is ... and then segmentation faults. See Question&Answers more detail:os...

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

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305 views

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c++ - Is it direct-initialization or copy-initialization?

Initializing objects (instances of classes or structs) in C++ can be done in various ways. Some syntaxes evoke ... of a non-optimizing compiler? See Question&Answers more detail:os...

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

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328 views

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c++ - How to generate random permutations with CUDA

What parallel algorithms could I use to generate random permutations from a given set? Especially proposals or links to papers ... 6, ..., 1}. See Question&Answers more detail:os...

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

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