使用PyQt5实现一个简单的图形界面计算器程序 点击按钮输入数字，在显示区域(白色只读框)回显 点击运算符输入运算符 点击等号(=)后，显示等号前计算式的计算结果 点击加减乘除运算符后，显示之前计算式的计算结果 点击按钮“Backspace“删除上一个输入的数字或运算符 点击按钮“C”清除已输入内容，并清除显示区域中的内容

好的，以下是一个简单的图形界面计算器程序的实现，使用了PyQt5库：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel, QLineEdit, QPushButton, QVBoxLayout

class Calculator(QWidget):

    def __init__(self):
        super().__init__()
        self.setWindowTitle('Calculator')
        self.setGeometry(100, 100, 300, 400)
        self.initUI()

    def initUI(self):
        self.answer_label = QLabel(self)
        self.answer_label.setStyleSheet('background-color:white')
        self.answer_label.setGeometry(10, 10, 280, 50)

        self.result_label = QLabel(self)
        self.result_label.setStyleSheet('background-color:white')
        self.result_label.setGeometry(10, 70, 280, 50)

        self.one_button = QPushButton('1', self)
        self.one_button.setGeometry(10, 130, 50, 50)
        self.one_button.clicked.connect(lambda: self.add_to_answer('1'))

        self.two_button = QPushButton('2', self)
        self.two_button.setGeometry(70, 130, 50, 50)
        self.two_button.clicked.connect(lambda: self.add_to_answer('2'))

        self.three_button = QPushButton('3', self)
        self.three_button.setGeometry(130, 130, 50, 50)
        self.three_button.clicked.connect(lambda: self.add_to_answer('3'))

        self.four_button = QPushButton('4', self)
        self.four_button.setGeometry(10, 190, 50, 50)
        self.four_button.clicked.connect(lambda: self.add_to_answer('4'))

        self.five_button = QPushButton('5', self)
        self.five_button.setGeometry(70, 190, 50, 50)
        self.five_button.clicked.connect(lambda: self.add_to_answer('5'))

        self.six_button = QPushButton('6', self)
        self.six_button.setGeometry(130, 190, 50, 50)
        self.six_button.clicked.connect(lambda: self.add_to_answer('6'))

        self.seven_button = QPushButton('7', self)
        self.seven_button.setGeometry(10, 250, 50, 50)
        self.seven_button.clicked.connect(lambda: self.add_to_answer('7'))

        self.eight_button = QPushButton('8', self)
        self.eight_button.setGeometry(70, 250, 50, 50)
        self.eight_button.clicked.connect(lambda: self.add_to_answer('8'))

        self.nine_button = QPushButton('9', self)
        self.nine_button.setGeometry(130, 250, 50, 50)
        self.nine_button.clicked.connect(lambda: self.add_to_answer('9'))

        self.zero_button = QPushButton('0', self)
        self.zero_button.setGeometry(70, 310, 50, 50)
        self.zero_button.clicked.connect(lambda: self.add_to_answer('0'))

        self.plus_button = QPushButton('+', self)
        self.plus_button.setGeometry(190, 130, 50, 50)
        self.plus_button.clicked.connect(lambda: self.add_to_answer('+'))

        self.minus_button = QPushButton('-', self)
        self.minus_button.setGeometry(190, 190, 50, 50)
        self.minus_button.clicked.connect(lambda: self.add_to_answer('-'))

        self.multiply_button = QPushButton('*', self)
        self.multiply_button.setGeometry(190, 250, 50, 50)
        self.multiply_button.clicked.connect(lambda: self.add_to_answer('*'))

        self.divide_button = QPushButton('/', self)
        self.divide_button.setGeometry(190, 310, 50, 50)
        self.divide_button.clicked.connect(lambda: self.add_to_answer('/'))

        self.equal_button = QPushButton('=', self)
        self.equal_button.setGeometry(250, 310, 50, 50)
        self.equal_button.clicked.connect(self.calculate_answer)

        self.clear_button = QPushButton('C', self)
        self.clear_button.setGeometry(250, 130, 50, 50)
        self.clear_button.clicked.connect(self.clear_answer)

        self.backspace_button = QPushButton('Backspace', self)
        self.backspace_button.setGeometry(250, 190, 50, 50)
        self.backspace_button.clicked.connect(self.backspace_answer)

    def add_to_answer(self, value):
        current_answer = self.answer_label.text()
        self.answer_label.setText(current_answer + value)

    def calculate_answer(self):
        current_answer = self.answer_label.text()
        try:
            result = eval(current_answer)
        except:
            result = 'Error'
        self.result_label.setText(str(result))

    def clear_answer(self):
        self.answer_label.setText('')
        self.result_label.setText('')

    def backspace_answer(self):
        current_answer = self.answer_label.text()
        self.answer_label.setText(current_answer[:-1])

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

这个程序有一个显示区域和一些按钮，可以输入数字和运算符，点击等号可以计算结果，点击Backspace可以删除上一个输入的数字或运算符，点击C可以清除已输入内容，并清除显示区域中的内容。