How to Restrict Input Content in QLineEdit in Qt

• Only allow input of integers:

  lineEdit->setValidator(new QIntValidator(lineEdit));
  

• Only allow input of numbers:

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

• Only allow input of letters and numbers:

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

• Only allow input of uppercase data:

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

• Only allow input of lowercase data:

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

• Only allow input of letters:

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