Spin Box
------------

- This example demonstrates how to use the QSpinBox widget:
  
.. code-block:: python
  :caption: scripts/PYQT2/02_sub_widget/02_spin_box/main.py
  :linenos:

  # -*- coding: utf-8 -*-

  import sys
  from PyQt5.QtWidgets import QApplication, QMainWindow, QSpinBox, QVBoxLayout, QWidget, QLabel

  class SpinBoxExample(QMainWindow):
      def __init__(self):
          super(SpinBoxExample, self).__init__()

          self.init_ui()

      def init_ui(self):
          layout = QVBoxLayout()

          self.label = QLabel("Selected Value:", self)

          self.spin_box = QSpinBox(self)
          self.spin_box.setRange(0, 100)  # 0부터 100까지의 범위 설정
          self.spin_box.setSingleStep(5)  # 5단위로 값 변경
          self.spin_box.setPrefix("$")    # 접두사로 달러 표시
          self.spin_box.valueChanged.connect(self.update_label)  # 값 변경 시 라벨 업데이트

          layout.addWidget(self.label)
          layout.addWidget(self.spin_box)

          container = QWidget()
          container.setLayout(layout)
          self.setCentralWidget(container)

      def update_label(self, value):
          self.label.setText("Selected Value: ${}".format(value))

  if __name__ == '__main__':
      app = QApplication(sys.argv)
      window = SpinBoxExample()
      window.show()
      sys.exit(app.exec_())

      
- ``QSpinBox``: A widget that allows the user to input an integer value. Users can click the arrows within the widget or directly input numbers to change the value.
  
- In this example, the ``QSpinBox`` ranges from 0 to 100, adjusting in increments of 5. It also prefixes the displayed value with the '$' sign. When the user changes the value, the connected slot function ``update_label`` is invoked to update the text of the label widget.