Recent questions tagged C++

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c++ - Error C1083: Cannot open include file: 'stdafx.h'

When I compiled this program (from C++ Programming Language 4th edition): main.cpp #include <stdafx.h> #include <iostream ... 7. How to fix 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++ - STL algorithms: Why no additional interface for containers (additional to iterator pairs)?

I'm wondering why the STL doesn't overload their algorithm functions such that I can call them by simply providing ... } Am I missing something? 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++ - Is constexpr a "hint" (like inline) or "a binding request" to the compiler?

Is constexpr an indicator for the compiler or does it mandate a behaviour ? The example at hand is the following ... request" to the compiler ? 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++ - Potential Problem in "Swapping values of two variables without using a third variable"

I recently came along this method for swapping the values of two variables without using a third variable. a^= ... terribly wrong with the code? 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++ - Spurious warning about binding temporary to reference member in constructor

I understand that if a temporary is bound to a reference member in the constructor's initializer list, the ... FOR A PARTICULAR PURPOSE. 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++ - Is it legal to modify the result of std::string::op[]?

Consider the following from C++11: [C++11: 21.4.5]: basic_string element access [string.access] ... this not rather ambiguous wording? 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++ - Is Visual Studio 2013 optimizing correctly in the presence of /OPT:ICF?

I expect the following program to return 0 all of the time. However with Visual Studio 2013 (Update 4), the program ... return 1; } 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++ - What are the reasons that extending the std namespace is considered undefined behavior?

Why is adding names to the std namespace undefined behaviour? The obvious answer is "because the standard says ... for this Undefined Behaviour? 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 can't I use <experimental/filesystem> with g++ 4.9.2?

I am trying to use filesystem. I have -std=c++11 -std=c++1y in my CMakeLists.txt. GCC version is 4 ... way to use std::experimental::filesystem? 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++ - Making only one column of a QTreeWidgetItem editable

I have a QTreeWidgetItem with two columns of data, is there any way to make only the second column editable? ... ); all columns become editable. 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 one double promote every int in the equation to double?

Does the presence of one floating-point data type (e.g. double) ensure that all +, -, *, /, %, etc math operations ... // equal to 4 or to 4.5? 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++ - Void Pointer Arithmetic

Given a void pointer, if I want to make the void pointer point to x bytes ahead, how will this be best done ... than casting to a char 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++ - How does sizeof know the size of the operand array?

This may be a stupid question but how does the sizeof operator know the size of an array operand when you don' ... curious as to how this works. 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 check if a file is gzip compressed?

I have a C / C++ program which needs to read in a file that may or may not be gzip compressed. I know we can ... file is gzipped from C / C++? 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++ - Qt - Determine absolute widget and cursor position

I have a QWidget that contains multiple children. The ultimate goal is to be able to drag and drop from one widget ... (mousePos)) { // Logic } 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 C++11 not support anonymous structs, while C11 does?

C11 supports anonymous structures, like so: struct Foo { struct { size_t x, y; }; }; struct Foo f; f.x ... standard. So why weren't they added? 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++ - QTextEdit vs QPlainTextEdit

What's the difference between QTextEdit and QPlainTextEdit, why use one over the other? I'm coding a text ... would compare the two classes. 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 is the meaning of `struct X typedef` vs. `typedef struct X`?

I have the following (working) code in an existing code base, used in include file that is shared between C ... below? Am I missing something? 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 `std::basic_ifstream<char16_t>` not work in c++11?

The following code works as expected. The source code, file "file.txt" and "out.txt" are all encoded with utf8 ... run-time as shown by @Brian. 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 set error_code to asio::yield_context

I'd like to create an asynchronous function which takes as it's last argument boost::asio::yield_context. E.g.: ... best. Is there another 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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226 views

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c++ - Hide the console of a C program in the Windows OS

I want to hide my console of C when I run my application. How can I make my application run in the background? 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++ - parsing into several vector members

I want to recursively parse a string and store the results in one struct. I've written a parser that can ... a simplification of my problem. 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 getline and std::istream::operator>>()?

#include <iostream> #include <string> using namespace std; int main() { string username; cout<< "username" ; cin ... getline (cin,username) ; } 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 it mean to return a reference?

I understand the concept of references in C++, and I understand what they do when used in function parameters, but ... { //insert useful code } 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++ - Explicit Type Conversion and Multiple Simple Type Specifiers

To value initialize an object of type T, one would do something along the lines of one of the following: ... a question about initialization). 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++ - STL map containing references does not compile

The following: std::map<int, ClassA &> test; gives: error C2101: '&' on constant While the following std::map ... does the first case not work? 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++ - Understanding how Lambda closure type has deleted default constructor

From 5.1.2 [19] The closure type associated with a lambda-expression has a deleted (8.4.3) default constructor and ... b = a; //all good though 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++ - SSE reduction of float vector

How can I get sum elements (reduction) of float vector using sse intrinsics? Simple serial code: void(float *input, ... result += input[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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