Qlineedit of QT notes (74) specifies the input type

One . Preface
The landlord is actually developing , The text box can only enter numbers or letters , I thought I needed to do event filtering by myself , little does one think Qt Relevant interfaces have been provided , The landlord then sorted out the records and shared them

Two . Example of setting limit input type
1. Only numbers are allowed

    ui->lineEdit->setValidator(new QIntValidator(ui->lineEdit_pid));
    ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("[0-9]+$")));

2. Only letters are allowed

ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("^[A-Za-z]+$")));

3. Only letters and numbers are allowed Case insensitive

ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("[a-zA-Z0-9]+$")));

4. Only uppercase letters are allowed

ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("^[A-Z]+$")));

5. Only lowercase letters are allowed

ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("^[a-z]+$")));

6. Only Chinese is allowed

ui->lineEdit->setValidator(new QRegExpValidator(QRegExp("[\u4e00-\u9fa5]+$")));