Recent questions tagged C++

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c++ - Wrapping FILE* with custom std::ostream

I have a function which works with a std::ostream. I need to support using a C file handle (FILE*). ... ostream which delegates to a FILE*? 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 tell if template type is an instance of a template class?

I have a function that takes a template type to determine a return value. Is there any way to tell at ... to test for all possible types. 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 is it that we can write outside of bounds in C?

I recently finished reading about virtual memory and I have a question about how malloc works within the Virtual address ... on a 32-bit system. 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++ - localtime returns GMT for windows programs running on cygwin shells

Consider the following code: time_t t; t = time( NULL ); elog << "timezone: " << getenv( "TZ" ) << ... ); timet += localTimeOffset; Good times. 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 is overloading operator&() prohibited for classes stored in STL containers?

Suddenly in this article ("problem 2") I see a statement that C++ Standard prohibits using STL containers ... ::addressof() workaround exists? 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 make C++11 functions taking function<> parameters accept lambdas automatically

C++11 has both lambda's and std::function<>, but unfortunately, they have different types. One consequence ... hope this clarifies the question. 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++ - SFINAE with C++14 return type deduction

Thanks to C++14, we'll soon be able to curtail verbose trailing return types; such as the generic min ... to return types which are integral? 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++ - G++ updated on MingW gets massive error messages

I'm on Windows 10 with MinGW, and recently updated my g++, using mingw-get update and mingw-get upgrade. This ... from c:mingwlibgccmingw324.9.3includec++ios:40:0, from c:mingwl...

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

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c++ - Why can one specify the size of an array in a function parameter?

I don't understand why the following example compiles and works: void printValues(int nums[3], int length) { for( ... . What is going on here? 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 get ride of console box of a GUI program compile by MinGW + Code::Block

When I compile and run a simple Win32 GUI program in MinGW+MSys with command line: $ g++ main.cpp -o app -std ... I get rid of the console box? 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++ - Observing quadratic behavior with quicksort - O(n^2)

The quicksort algorithm has an average time complexity of O(n*log(n)) and a worst case complexity ... Sorting and Selection Algorithms 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++ - Compound literals in MSVC

In GCC, I'm able to do this: (CachedPath){ino} inode->data = (struct Data)DATA_INIT; where: struct ... implementations of C++ is appreciated. 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++ - Split string using loop to specific length sub-units

I need to split a string into specific lengths, e.g. if user specifies it to units of max length 4, then ... is less than the specified length). 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++ - lvalue required as increment operand error

#include <stdio.h> int main() { int i = 10; printf("%d ", ++(-i)); // <-- Error Here } What is wrong with ++(-i)? Please clarify. 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++ - Must a reference type be initialized in constructor initialization list?

As self-exercise, I have written this simple code: #include <iostream> int gIndex = 3; template <class ... in constructor initialization list? See Question&Answers more detail:os...

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

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161 views

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c++ - How to traverse graph in boost use BFS

I have problems getting to compile the BFS of a very simple graph. Whatever I do I get various compiler messages about ... " but it didn't 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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512 views

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c++ - How to output float to cout without scientific notation or trailing zeros?

What is the most elegant way to output a floating point number in C++ with no scientific notation or trailing ... don't want trailing zeros. See Question&Answers more detail:os...

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

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378 views

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c++ - Why is comparing two parameters of a constexpr function not a constant condition for static assertion?

constexpr uint32_t BitPositionToMask(int i,int Size){ static_assert(i < Size,"bit position out of range"); return 1 << i; ... ; return 1 << i; } 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 parameter cannot be deduced

I don't understand why T cannot be deduced in this scenario: template<class T> class MyType { T * ... the compiler have enough information? 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++ - Trying to link Boost 1.52 thread

I am trying to compile my program but it wouldn't link at all. I have specified the path to the boost lib ... boost 1.52. Will update later. See Question&Answers more detail:os...

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

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509 views

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c++ - initializing char arrays in a way similar to initializing string literals

Suppose I've following initialization of a char array: char charArray[]={'h','e','l','l','o',' ' ... . I'm thankful for your answers. See Question&Answers more detail:os...

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

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415 views

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c++ - Confusion about in-class initialization of static data members

I'm reading lippman's c++ primer where on p. 303 they give this: class Account { private: static constexpr int ... said I should get. Why not? See Question&Answers more detail:os...

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

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232 views

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c++ - Binding temporary to a lvalue reference

I have the following code string three() { return "three"; } void mutate(string& ref) { } int main() { ... tried : VS 2008 and VS2010 Beta 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++ - Class inherited from class without default constructor

Right now I have a class A that inherits from class B, and B does not have a default constructor. I am trying ... ) How would I fix this error? 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++ - Cannot have typeof(std::endl) as template parameter?

So, I was trying to write a function like this: void append_to_stream(std::ostream &stream) { } template < ... 've added using namespace std; 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++ - Is it possible to use cin with Qt?

Is it possible to use cin in Qt? I can use cout but cannot find examples of how to use cin within a Qt console application. See Question&Answers more detail:os...

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

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547 views

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c++ - Understanding gsl::narrow implementation

The C++ Core Guidelines has a narrow cast that throws if the cast changes the value. Looking at the microsoft ... <U>::value> { }; See Question&Answers more detail:os...

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

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216 views

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c++ - GDB jumps to wrong lines in out of order fashion

Application Setup : I've C++11 application consuming the following 3rd party libraries : boost 1.51.0 cppnetlib ... root causing this issue ? See Question&Answers more detail:os...

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

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