Qt实现QLineEdit输入前提示输入范围并用正则表达式限制输入范围

    //设置输入范围，实现输入框只能输入0.0-100.0且小数点后两位
    QDoubleValidator *validator = new QDoubleValidator(0.0, 100.0, 2);
    m_myLineEdit->setValidator(validator);

    QIntValidator *validator = new QIntValidator(0, 100);
    m_myLineEdit->setValidator(validator);

#include <QWidget>
#include <QLineEdit>

class MyLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    explicit MyLineEdit(QWidget *parent = nullptr);
public:
    //设置最大最小输入范围
    void setMaxValue(double max);
    void setMinValue(double min);
signals:

public slots:
    //当输入的值不在范围内，光标离开编辑框时清空
    void slotClearEdit(QString text);
private:
    double m_max;
    double m_min;
};

#include "MyLineEdit.h"

MyLineEdit::MyLineEdit(QWidget *parent) : QLineEdit(parent)
{
    connect(this, SIGNAL(textChanged(QString)), this, SLOT(slotClearEdit(QString)));
}

void MyLineEdit::setMaxValue(double max)
{
    m_max = max;
}

void MyLineEdit::setMinValue(double min)
{
    m_min = min;
}

void MyLineEdit::slotClearEdit(QString text)
{
    if(text.toDouble() < m_min || text.toDouble() > m_max)
    {
        this->clear();
    }
}

#include "MainWindow.h"
#include "ui_MainWindow.h"
#include "MyLineEdit.h"
#include <QGridLayout>
#include <QDoubleSpinBox>
#include <QIntValidator>
#include <QDoubleValidator>
#include <QRegExpValidator>

MainWindow::MainWindow(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::MainWindow),
    m_myLineEdit(nullptr),
    m_lab(nullptr)
{
    ui->setupUi(this);
    initUI();
}

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

void MainWindow::initUI()
{
    QGridLayout* layout = new QGridLayout(this);
    m_myLineEdit = new MyLineEdit();
    m_lab = new QLabel("输入：");
    layout->addWidget(m_lab, 0, 0);
    layout->setColumnStretch(0,1);
    layout->addWidget(m_myLineEdit, 0, 1);
    layout->setColumnStretch(1,4);

    //设置lineedit的提示
    m_myLineEdit->setPlaceholderText("请输入0.0-100.0的数");
    //设置最大最小值
    m_myLineEdit->setMaxValue(100.0);
    m_myLineEdit->setMinValue(0.0);
    //设置输入范围
    QDoubleValidator *validator = new QDoubleValidator(0.0, 100.0, 2);
    m_myLineEdit->setValidator(validator);
}

   //设置lineedit的提示
   m_myLineEdit->setPlaceholderText("请输入0-100的数");
   //设置最大最小值
   //m_myLineEdit->setMaxValue(100);
   //m_myLineEdit->setMinValue(0);
   //设置输入范围
   QRegExpValidator *validator = new QRegExpValidator(QRegExp("\\d{2}|100"), this);
   m_myLineEdit->setValidator(validator);