Tips：

参数重载时需要函数指针明确重载的是哪一个，避免出现二义性

 案例修改：

重载学生类中的treat函数，增加foodName参数

//Teacher.h
#ifndef TEACHER_H
#define TEACHER_H

#include <QObject>

class Teacher : public QObject
{
    Q_OBJECT
public:
    explicit Teacher(QObject *parent = 0);

    //自定义信号 写到signals下
    //1：返回值是woid
    //2：只需要声明，不需要实现
    //3：可以有参数，可以发生重载

signals:
    void hungry();
    void hungry(QString foodName);

public slots:
};

#endif // TEACHER_H

//Student.h
#ifndef STUDENT_H
#define STUDENT_H

#include <QObject>

class Student : public QObject
{
    Q_OBJECT
public:
    explicit Student(QObject *parent = 0);

signals:

//槽函数写在public solts下，或者public下，或者全局函数，lambda
//    返回值为void
//    需要声明，需要实现
//    可以有参数，可以重载
public slots:
    void treat();
    void treat(QString foodName);
};

#endif // STUDENT_H

//Student.cpp
#include "student.h"
#include "QDebug"

Student::Student(QObject *parent) : QObject(parent)
{

}

void Student::treat(){
    qDebug()<<"请老师吃饭";
}

void Student::treat(QString foodName){
    qDebug()<<"请老师吃饭,老师要吃:"<<foodName;
}

//widget.cpp
#include "widget.h"

//Teacher老师类 Student 学生类
//下课，老师发送饿了的信号，学生响应信号，请老师吃饭

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    //加this则不需要手动delete
    this->zt = new Teacher(this);
    this->st = new Student(this);

    // 连接信号和槽
//    connect(this->zt,&Teacher::hungry,this->st,&Student::treat);

    //连接有参的信号和槽
    //函数指针 指向 函数地址
    void (Teacher:: * teacherSignal)(QString) = &Teacher::hungry;
    void (Student:: *studentSlot)(QString) = &Student::treat;
    connect(this->zt,teacherSignal,this->st,studentSlot);

    //下课函数调用
    classOver();
}

void Widget::classOver(){
    //触发自定义信号
    emit this->zt->hungry();

    //触发有参信号
    emit this->zt->hungry("宫保鸡丁");
}

Widget::~Widget()
{

}

运行结果：QString默认加双引号

 如果想要去掉双引号，需要将QString转换为char*

void Student::treat(QString foodName){
    //QSTring 转为char*
    //先调用toUtf-8 转为QByteArray
    //再调用data转为char*
    qDebug()<<"请老师吃饭,老师要吃:"<<foodName.toUtf8().data();
}