Recent questions tagged C++

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c++ - Boost Spirit Qi: Omit element in Kleene Star parser

I want to parse special constructs and throw the rest away. But I don't want to use a skipper. I want to get a ... "failure" << std::endl; } } 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++ - Using boost::spirit::qi to parse numbers with separators

I am attempting to use boost::spirit::qi to do some parsing. It's actually going quite well, and I successfully have ... std::endl; return 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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c++ - Difference between lookup rules for friend function defined inside vs outside of the class

The following code: struct X { X() {} }; struct Y { Y() {} Y(X) {} Y(int) {} friend bool ... But I don't quite understand what it means. 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++ - g++ cannot find header file

I am migrating from Java to C++. It seems that C++ makes classes declaration in separate files, ... directory compilation terminated. 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++ - How does function-style cast syntax work?

I guess I am a bit puzzled by the syntax. What does the following mean? typedef char *PChar; hopeItWorks = PChar( 0x00ff0000 ); See Question&Answers more detail:os...

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

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532 views

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c++ - Multi-Dimensional Arrays in Memory

I am wondering if the C++ standard guarantees that multidimensional arrays (not dynamically allocated) are flattened into ... keep y[i] aligned? 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++ - Generate subsequences

I have a string like "0189", for which I need to generate all subsequences, but the ordering of the individual ... C/C++ would be 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++ - How to compile a project with C++11 under Xcode 8?

This question was asked many times and I failed to replicate all of the solutions I could find. I am unable to ... it will work for me too. 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++ - Programs compiles in g++ but exits with linker errors in gcc

I'm trying out the solution to a question about specialized template classes. This code with a compiles fine in g++, but ... f(); */ return 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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c++ - After writing BMP file, image is flipped upside down

I am using the following code: f = fopen( _stringhelper.STR("%s.bmp", filename), "wb" ); if( !f ) { _core ... t get it. What may be the problem? 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++ - Inserting a comment in __asm results in C2400 error (VS2012)

I was trying to check the compiled assembler of some code in VS 2012. I added two lines (before and ... adding an instruction, including NOP? 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 a const cast do differently?

Is there an actual difference between a const_cast and c style cast (ObjectType) ? 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++ - Problem overridding virtual function

Okay, I'm writing a game that has a vector of a pairent class (enemy) that s going to be filled with children ... it to call B's print function? See Question&Answers more detail:os...

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

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400 views

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c++ - Whitespace skipper when using Boost.Spirit Qi and Lex

Let's consider following code: #include <boost/spirit/include/lex_lexertl.hpp> #include <boost/spirit/include/qi.hpp> ... it like it is now? See Question&Answers more detail:os...

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

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326 views

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c++ - Boost.Spirit.Qi crashes when assigning rule to a sequence including itself

I have the following MWE: #include <string> #include <boost/spirit/include/qi.hpp> #include <boost/spirit/include/phoenix ... , one at a time. See Question&Answers more detail:os...

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

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681 views

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c++ - Can't get "a" to output a beep sound

I'm on another person's Mac-book Pro and I'm trying to output the alarm sound in C++ by outputting "a" ... be happening? I'm using Eclipse. See Question&Answers more detail:os...

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

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427 views

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c++ - can not print global objects in gdb

I have this simple c++ code : #include<bits/stdc++.h> using namespace std; vector<string> q; int main() { ... No symbol "q" in current context. See Question&Answers more detail:os...

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

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551 views

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c++ - how to access a text file while debugging with eclipse CDT

I am writing this code to access a file in eclipse CDT ifstream inFile; ofstream outFile; string next; inFile.open( ... should I put the file? See Question&Answers more detail:os...

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

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621 views

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c++ - inner loop with same variable name as outer loop

assuming the following simple code: for(int i=0; i < 1000; i++) { cout << "Outer i: " << i << endl; ... i from outer loop. A bit confused I am. 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++ - Cannot access private member in singleton class destructor

I'm trying to implement this singleton class. But I encountered this error: 'Singleton::~Singleton': cannot access ... ++ 6.0 to compile. See Question&Answers more detail:os...

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

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532 views

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c++ - Preventing slicing in copy constructor

I want to copy a vector of type Foo objects but the objects can be several different derived types of Foo. ... I copy the data without slicing? See Question&Answers more detail:os...

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

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564 views

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c++ - Boost asio TCP async server not async?

I am using the code provided in the Boost example. The server only accepts 1 connection at a time. This ... second connection in the meantime. See Question&Answers more detail:os...

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

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541 views

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c++ - Why is forwarding reference constructor called instead of copy constructor?

Given the following code #include <iostream> using namespace std; template <typename Type> struct Something { ... defined in stack overflow. See Question&Answers more detail:os...

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

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331 views

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c++ - Multi-threaded GEMM slower than single threaded one?

I wrote some Naiive GEMM code and I am wondering why it is much slower than the equivalent single threaded GEMM code ... std::move(result); } 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++ - When are variable-length arrays legal?

I'm not a C++ expert, but as far as I know this code should fail due to size not being constant: #include<iostream> ... )? ./test 7 7 /test 2 2 See Question&Answers more detail:os...

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

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506 views

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c++ - msvc is_copy_assignable always true?

#include <type_traits> class Test { public: Test(const Test &) = delete; Test &operator=(const Test &) = ... way to test for this condition? See Question&Answers more detail:os...

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

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410 views

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c++ - this is not a real pointer?

I am reading something about virtual table. When it comes to pointer __vptr, it is stated that by the author Unlike ... is not a real pointer? See Question&Answers more detail:os...

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

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391 views

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c++ - Function template with reference template parameter

There is this code: #include <iostream> template<const double& f> void fun5(){ std::cout << f << std::endl; ... should be done to make it 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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