在 Linux（Ubuntu 13.10 和 14.04）下运行没​​有 QtCoreApplication/QCoreApplication 的 Qt C++ 代码

Posted 2023-02-14

【中文标题】在 Linux（Ubuntu 13.10 和 14.04）下运行没​​有 QtCoreApplication/QCoreApplication 的 Qt C++ 代码

【英文标题】：Running Qt C++ code without QtCoreApplication/QCoreApplication under Linux (Ubuntu 13.10 and 14.04)

【发布时间】：2015-01-06 17:47:06

【问题描述】：

我在 Linux 下运行我的程序时遇到了一个奇怪的错误。消息说： QApplication::qAppName: 请先实例化 QApplication 对象。 它在 Windows 8 下正常运行，但我想将它移植到没有这种依赖关系的 Linux 上。 这是我的代码：

#include <QtCore/QCoreApplication>
#include <iostream>
#include <omd/opto.h>
#include <QThread>

int main(int argc, char *argv[])

//QCoreApplication a(argc, argv);

OptoPorts ports;
OPort* list=ports.listPorts(true);

std::cout<<"Available ports:"<<std::endl;
std::cout<<std::endl;
int i=0;
for (i=0;i<ports.getLastSize();i++)
    std::cout<<"   "<<i+1<<". "<<list[i].name<<" "<<list[i].deviceName<<std::endl;

std::cout<<ports.getLastSize();

std::cout<<std::endl;

if (i==0)
    
    std::cout<<"No sensor found"<<std::endl;
    return -1;
    

        int input;
        int timing;

        if (ports.getLastSize()==1)
            input=1;
        else
            std::cin>>input;

        OptoDAQ daq;
        daq.open(list[input-1]);


        while (true)
        
        if (daq.getVersion()!=_95)
        
                    OptoPackage* pa=0;

                    int size=daq.readAll(pa);

                    for (int i=0;i<size;i++)
                    
                    std::cout<<"x: "<<pa[i].x<<" y: "<<pa[i].y<<" z: "<<pa[i].z<<" s1: "<<pa[i].s1<<" s2: "<<pa[i].s2<<" s3: "<<pa[i].s3<<" s4: "<<pa[i].s4<<" TEMP: "<<pa[i].temp<<std::endl;
                    
        
        else if (daq.getVersion()==_95)
        
        OptoPackage6D* p6d=0;
        int size=daq.readAll6D(p6d,false);

        std::cout<<"SIZE:"<<size<<std::endl;
        for (int i=0;i<size;i++)
        
            std::cout<<"Sensor1.x: "<<p6d[i].Sensor1.x<<" Sensor1.y: "<<p6d[i].Sensor1.y<<" Sensor1.z: "<<p6d[i].Sensor1.z<<" Sensor1.s1: "<<p6d[i].Sensor1.s1<<" Sensor1.s2: "<<p6d[i].Sensor1.s2<<" Sensor1.s3: "<<p6d[i].Sensor1.s3<<"  Sensor1.s4: "<<p6d[i].Sensor1.s4<<" TEMP: "<<p6d[i].Sensor1.temp<<std::endl;
            std::cout<<"Sensor2.x: "<<p6d[i].Sensor2.x<<" Sensor2.y: "<<p6d[i].Sensor2.y<<" Sensor2.z: "<<p6d[i].Sensor2.z<<" Sensor2.s1: "<<p6d[i].Sensor2.s1<<" Sensor2.s2: "<<p6d[i].Sensor2.s2<<" Sensor2.s3: "<<p6d[i].Sensor2.s3<<"  Sensor2.s4: "<<p6d[i].Sensor2.s4<<" TEMP: "<<p6d[i].Sensor2.temp<<std::endl;
            std::cout<<"Sensor3.x: "<<p6d[i].Sensor3.x<<" Sensor3.y: "<<p6d[i].Sensor3.y<<" Sensor3.z: "<<p6d[i].Sensor3.z<<" Sensor3.s1: "<<p6d[i].Sensor3.s1<<" Sensor3.s2: "<<p6d[i].Sensor3.s2<<" Sensor3.s3: "<<p6d[i].Sensor3.s3<<"  Sensor3.s4: "<<p6d[i].Sensor3.s4<<" TEMP: "<<p6d[i].Sensor3.temp<<std::endl;
            std::cout<<"Sensor4.x: "<<p6d[i].Sensor4.x<<" Sensor4.y: "<<p6d[i].Sensor4.y<<" Sensor4.z: "<<p6d[i].Sensor4.z<<" Sensor4.s1: "<<p6d[i].Sensor4.s1<<" Sensor4.s2: "<<p6d[i].Sensor4.s2<<" Sensor4.s3: "<<p6d[i].Sensor4.s3<<"  Sensor4.s4: "<<p6d[i].Sensor4.s4<<" TEMP: "<<p6d[i].Sensor4.temp<<std::endl;
        
        

        QThread::msleep(50);
        

        daq.close();


//return a.exec();
return 0;

【问题讨论】：

为什么QCoreApplication 行被注释掉了？

QCoreApplication 是强制性的。如果你只使用 Qt 中的 QThread::msleep，你应该考虑从 C++11 迁移到 std::this_thread::sleep_for 并完全摆脱你的 Qt 依赖。

如何忽略 QCoreApplication 在 Code::Blocks 或 NetBeans 下运行我的代码？

【参考方案1】：

如果你所做的只是 QThread::msleep，你就不需要 QCoreApplication。我建议使用标准库进行睡眠，但如果你坚持，这对我来说在 Qt5 的 Windows 8.1 和 Ubuntu 15.04 中都很好。

main.cpp:

#include <QThread>

int main()

    QThread::sleep(5);
    return 0;

使用 CMake 进行两端配置，无需更改任何内容：

CMakeLists.txt：

cmake_minimum_required(VERSION 2.8.11)

find_package(Qt5Core REQUIRED)

add_executable(main main.cpp)
qt5_use_modules(main Core)