c++

问题 Currently, I can compose ranges-v3 views like this: auto v = ranges::view::reverse | ranges::view::filter([](int l){return l>5;}); But if I wanted to return v from a function I'd need to know its type. What is the type of a ranges-v3 view? 回答1: Since C++14 you can use auto as the return type of functions and it will get deduced: auto f() { return ranges::view::reverse | ranges::view::filter([](int l){return l>5;}); } // f's return type is the type of the return expression, exactly as is I had

问题 I want to disable/grey a system menu button on the console window, particularly the minimize button. I've tried functions mentioned on another thread, but even after using them, the console window still doesn't have the minimize button grayed out. I have also looked into the DeleteMenu() function, but it doesn't seem to have the option to grey out buttons. Here's the test code: #include <Windows.h> using namespace std; int main() { //SetConsoleTitle(L"CPU Information"); HWND consoleWindow =

问题 I am working on project with Qt Quick Control 2 . When I try to run my software in debug mode FileDialog.qml opens perfectly but when I deploy it as release mode it doesn't work. Here is my code: import QtQuick 2.4 import QtQuick.Window 2.2 import QtQuick.Controls 1.3 import QtQuick.Dialogs 1.0 // File Dialog to browse FileDialog { id: openDialog title: "Please Select An Image" folder: shortcuts.pictures nameFilters: ["Image files (*.BMP)"] modality: Qt.NonModal selectExisting: true /* * do

问题 I am writing a Key board emulator program in Linux, As a start I was able to render key strokes into X11 window but this is not working in virtual terminals and try out a different way. I referred to http://thiemonge.org/getting-started-with-uinput and tried with uinput kernel module. According to the tutorial key strokes can be injected as a uinput event and I wrote below code accordingly. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <fcntl.h>

问题 If I have the data look like this: Michael 30 Tom 35 I can handle it by the following code: #include <iostream> #include <string> int main() { std::string name; int age; while(std::cin >> name >> age) { std::cout << name << " is " << age << " years old." << std::endl; } return 0; } However if my data looks like this: Michael Corleone 30 Tom Hagen 35 I tried using this code, but it only read the first line , the logic seems that it should read all the lines, so I don't know why this attempt

问题 I am trying to create Error bar in QT using Box and Whiskers. I get the following plot: But desired is something like this Code for box i used is: QBoxSet *box = new QBoxSet(0); box->setValue(QBoxSet::LowerExtreme, min); box->setValue(QBoxSet::UpperExtreme, max); box->setValue(QBoxSet::LowerQuartile,fres); The QBoxSet::LowerExtreme is behind the box, how I can move it on top of the box? or is there any other method to do this? 来源： https://stackoverflow.com/questions/46276086/error-bar-in-qt

问题 I'm trying to create a wrapper class W in C++, which is constructed with a pointer to a generic object OBJ . When you call one of OBJ methods through W , W (containing a condition variable cv ) issues a cv.wait() before calling OBJ method and a cv.notify() when OBJ method has finished. I've been able to do it with inheritance for a specific class, but would like a generic approach like the one described above. This is the inheritance approach: struct A { virtual void foo(int i) { bar = i; };

问题 I have 2 yocto pkgs that can be successfully compiled with gcc 5.4, cmake 3.6.1 on yocto 2.0.2 but I'm facing the following issue with: gcc 6.3, cmake 3.6.1 on yocto 2.4 . After some research, I observed that yocto changed the sysroot structure (sysroot per package instead of a common sysroot). The error looks like this: CMake Warning at src/mytest/CMakeLists.txt:71 (add_executable): Cannot generate a safe linker search path for target mytest because files in some directories may conflict

问题 I'm trying to create a wrapper class W in C++, which is constructed with a pointer to a generic object OBJ . When you call one of OBJ methods through W , W (containing a condition variable cv ) issues a cv.wait() before calling OBJ method and a cv.notify() when OBJ method has finished. I've been able to do it with inheritance for a specific class, but would like a generic approach like the one described above. This is the inheritance approach: struct A { virtual void foo(int i) { bar = i; };

问题 As of late I have been working extensively with struct and classes in visual studio.Most of them have a lot of values witch makes them hard to track in the watch windows while debugging because the watch windows and the floating watch windows ( the one you can pin , dont know precise term ) always show the memory address which obscures the view of the values. Is there a way to make it so that the watch windows only show the values and not memory addresses 回答1: Write the custom natvis would be