Recent questions tagged C++

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c++ - Conflict between copy constructor and forwarding constructor

This problem is based on code that works for me on GCC-4.6 but not for another user with CLang-3.0, ... error for coming up with a conflict? 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++ - When would you use an array rather than a vector/string?

I'm a beginner C++ programmer and so I've learnt using arrays rather than vectors (this seems to be the ... classic array/char* (if ever)? 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++ - Use CreateProcess to Run a Batch File

I am trying to use CreateProcess to start a new environment block and run a batch file in the new environment ... INFINITE); return TRUE; } 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++ - Move out element of std priority_queue in C++11

Minimal working example. #include <cassert> #include <list> #include <queue> //#define USE_PQ struct MyClass { const ... same error with 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++ - Why does a function declaration with a const argument allow calling of a function with a non-const argument?

Take note of the following C++ code: #include <iostream> using std::cout; int foo (const int); int main ... Why are there no compilation errors? 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 can I get the mouse position in a console program?

How can I get the mouse click position in C++ in a Windows console program? (A variable that returns the ... the mouse position when clicked. 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++ - Portable end of line (newline)

It's been an unpleasant surprise that ' ' is replaced with " " on Windows, I did not know that. (I am ... program doing the text file I/O. 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 std::launder be used to convert an object pointer to its enclosing array pointer?

The current draft standard (and presumably C++17) say in [basic.compound/4]: [ Note: An array object ... to its enclosing array pointer? 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++ - cmake include header into every source file

I actually have a simple question, but couldn't find an answer. Maybe you can point me to a duplicate. So, ... to put #include foo.h? 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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c++ - name hiding and fragile base problem

I've seen it stated that C++ has name hiding for the purposes of reducing the fragile base class problem. ... , because it's an overload. See Question&Answers more detail:os...

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

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523 views

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c++ - How do I find the current directory?

I am trying to read a file which I read previously successfully. I am reading it through a library, and I ... is the current/working directory? 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's the difference between type(myVar) and (type)myVar?

I'm going through the full tutorial at cplusplus.com, coding and compiling each example manually. Regularly, I ... way rather than the other? 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 write a password-safe class?

This question follows a suggestion made by @sharptooth in this related question. Can std::string be tweaked so ... it before destruction) ? See Question&Answers more detail:os...

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

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549 views

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c++ - How serious is the new/delete operator mismatch error?

I have discovered the classic new/delete mismatch error in our codebase as follows: char *foo = new char[10]; ... or Corrupt memory is some way? See Question&Answers more detail:os...

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

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538 views

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c++ - How do you tell pyximport to use the cython --cplus option?

pyximport is super handy but I can't figure out how to get it to engage the C++ language options for ... the equivalent with pyximport? 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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427 views

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c++ - Can I get polymorphic behavior without using virtual functions?

Because of my device I can't use virtual functions. Suppose I have: class Base { void doSomething() { } }; ... the compiler doesn't support 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++ - sprintf for unsigned _int64

I am having following code. output of second %d in sprintf is always shown as zero. I think i am specifying wrong ... XML file size = 0 bytes See Question&Answers more detail:os...

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

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488 views

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c++ - About Pointers To Functions in function declarations

#include<stdio.h> #include<stdlib.h> int fun1() { printf("I am fun1."); return 0; } int fun2(int fun()) { ... fun2(int fun()) works. Thank you. See Question&Answers more detail:os...

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

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580 views

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c++ - How to enforce copy elision, why it won't work with deleted copy constructor?

I have an uncopiable class. Copying this would be problematic. I want to guarantee that it won't be ever copied, ... ever called. Why is it so? 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++ - Passing a lambda into a function template

I'm learning C++, and I'm trying to implement a binary search function that finds the first element for which ... my lambda has the right type? See Question&Answers more detail:os...

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

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433 views

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c++ - Why is a class allowed to have a static member of itself, but not a non-static member?

class base { public: base a; }; It gives compilation error. class base { public: static base a; }; ... code does not give compilation 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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394 views

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c++ - How do I run the preprocessor on local headers only?

I want the preprocessor to read in the includes of local headers, but ignore the includes of system headers. ... processing of system headers. See Question&Answers more detail:os...

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

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558 views

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c++ - gprof reports no time accumulated

I'm trying to profile a C++ application with gprof on a machine running OSX 10.5.7. I compile with g++ in ... gprof gmon.out | less Any ideas? 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++ - __attribute__((format(printf, 1, 2))) for MSVC?

With GCC, I can specify __attribute__((format(printf, 1, 2))) , telling the compiler that this function ... + compiler have anything similar ? 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 clearing a vector affect its capacity?

I instantiate an std::vector foo(1000). foo.size() is now 1000 and foo.capacity() is also 1000. If I ... the standard say anything about that? See Question&Answers more detail:os...

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

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495 views

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c++ - Is it possible to connect a signal to a static slot without a receiver instance?

Is it possible to connect a signal to static slot without receiver instance? Like this: connect(&object, SIGNAL(some() ... Qt 5 it is possible. See Question&Answers more detail:os...

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

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575 views

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c++ - std::optional specialization for reference types

Why std::optional (std::experimental::optional in libc++ at the moment) does not have specialization for ... existing object semantics in STL? See Question&Answers more detail:os...

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

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671 views

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c++ - Specialization of 'template<class _Tp> struct std::less' in different namespace

I am specializing the 'less' (predicate) for a data type. The code looks like this: template<> struct std::less< ... the "old way" still valid? See Question&Answers more detail:os...

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

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