c++ - 由于连接信号和槽的问题导致代码崩溃

Question

我有以下代码创建people 对象并通过QVector 存储对象。出于调试目的，我添加了一个名为 foo() 的信号和一个名为 outputData() 的插槽，以查看 QVector (list) 是否存储值正确。

我通过以下方式连接了信号和插槽:

 connect(People, SIGNAL(foo()), this , SLOT( outputData() ) ); 

在 mainwindow.cpp 文件上。 Gcc 构建代码并且不输出任何错误或警告。但是，当我运行该程序时，SIGSEV 终止了该进程。

谁能告诉我 connect() 的错误是什么？

QVector 存储对象的正确用法是什么？

code.pro

QT       += core gui
QT += network

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled1
TEMPLATE = app


SOURCES += main.cpp\
        mainwindow.cpp \
    people.cpp

HEADERS  += mainwindow.h \
    people.h

FORMS    += mainwindow.ui

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QUdpSocket>
#include <QString>
#include "people.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);

    ~MainWindow();
   // void outputData();
public slots:
    void outputData();
private slots:
    void readyRead();



signals: void foo();

private:
    Ui::MainWindow *ui;
    QUdpSocket udpSocket;
    people *People;
    void processPendingDatagrams();
    void udp_transfer(QString data);
    void ParseData(QByteArray data);
};
#endif // MAINWINDOW_H

---

people.h

#ifndef PEOPLE_H
#define PEOPLE_H

#include <QObject>
#include <QString>
#include <QMainWindow>

class people : public QObject
{
    Q_OBJECT
public:
    people();
    people(QString Name, int Age);
    QString getName();
    int getAge();
    void setName(QString Name);
    void setAge(int Age);


private:
   QString name;
   int age;
};

#endif // PEOPLE_H

---

main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

---

主窗口.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QHostAddress>
#include <QtNetwork>
#include <QVector>


QVector<people*> list;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
   udpSocket.bind(2222); 
    connect(&udpSocket, SIGNAL(readyRead()), this, SLOT(readyRead()));
    connect(People, SIGNAL(foo()), this , SLOT( outputData() ) );   //HERE IS THE PROBLEMATIC PART!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
}


MainWindow::~MainWindow()
{
    delete ui;
}


void MainWindow::readyRead(){
    do {
      QByteArray datagram;
      datagram.append(udpSocket.pendingDatagramSize());
      udpSocket.readDatagram(datagram.data(), datagram.size());
      ParseData(datagram);
    } while (udpSocket.hasPendingDatagrams());

}



void MainWindow::ParseData(QByteArray data){
    QString name;
    int i = 0;
    for (i=0; i<4; i++){
        name.append(QString("%1").arg(data[i]));
    }

    QString temp;
    for (i=0; i<2; i++){
        temp.append(QString("%1").arg(data[i+4]));
    }
    int age = temp.toInt();
    People = new people(name, age);
    qDebug() << "msg is received";
    list.push_back(People);
    emit foo();

}


void MainWindow::outputData(){
    qDebug() << "size:" << list.size();
    qDebug() <<  "name:" << list[0]->getName();
    qDebug() <<  "Age:" << list[0]->getAge();
}

---

人.cpp

#include "people.h"

people::people(){
   name = "No name";
   age = 0;
}

people::people(QString Name, int Age){
   name = Name;
   age = Age;
}

QString people::getName(){
    return name;
}

int people::getAge(){
   return age;
}

void people::setName(QString Name){
    name = Name;
}

void people::setAge(int Age){
    age = Age;
}

Answer 1

People 似乎是一个未初始化的指针。您不创建 people 对象，而只是在 connect 调用中使用未初始化的指针。然后，这将尝试在 People 可能指向的任何随机内存位置访问 people 对象，从而导致段错误。

您可能想先创建 People 对象，例如将 People(new people()) 添加到初始化列表。