Question

所以我目前正在制作GUI计算器，但我不确定如何编写将执行计算器操作的代码。现在我目前已经设置了窗口，输入框和计算器按钮，但目前它们都没有做任何事情。

我对如何在代码中表示这些按钮感到困惑，因此我不确定如何编写能够读取这些按钮输入并执行加法，减法等的代码块。

到目前为止，这是我的代码

class Calculator(Frame):
def __init__(self,master):
    Frame.__init__(self,master)
    self.grid()

    self.dataEnt = Entry(self)
    self.dataEnt.grid(row = 0, column = 1, columnspan = 4)

    labels =[['AC','%','/'],
         ['7','8','9','*'],
         ['4','5','6','-'],
         ['1','2','3','+'],
         ['0','.','=']]
    label = Button(self,relief = RAISED, padx = 10, text = labels[0][0]) #AC
    label.grid(row = 1, column = 0, columnspan = 2)
    label = Button(self,relief = RAISED, padx = 10, text = labels[0][1]) # %
    label.grid(row = 1, column = 3)
    label = Button(self,relief = RAISED, padx = 10, text = labels[0][2]) # /
    label.grid(row = 1, column = 4)
    for r in range(1,4):
        for c in range(4):
            #create label for row r and column c 
            label = Button(self,relief = RAISED,
                          padx = 10,
                          text = labels[r][c]) # 789* 456- 123+ 
            # place label in row r and column c
            label.grid(row = r+1, column = c+1)

    label = Button(self,relief = RAISED, padx = 10, text = labels[4][0]) #0
    label.grid(row = 5, column = 0, columnspan = 2)
    label = Button(self,relief = RAISED, padx = 10, text = labels[4][1]) # .
    label.grid(row = 5, column = 3)
    label = Button(self,relief = RAISED, padx = 10, text = labels[4][2]) # =
    label.grid(row = 5, column = 4)

  def operations(self,num ):

def main():
    root = Tk()
    root.title('Calculator')
    obj = Calculator(root)
    root.mainloop()

and here is what the calculator looks like so far

我的猜测是我需要能够以某种方式将输入作为字符串读取然后让python将该字符串作为数学表达式进行评估，但我不确定如何去做。

感谢您的帮助！

Answer 1

您可以做的是绑定所有按钮到标识按钮的方法，并将字符串附加到列表或评估表达式。然后可以在标签中显示该列表。

def button_press(self, event):
    widget = event.widget
    text = widget["text"]
    if text != "AC" and text != "=":
        self.operations.append(text)
    elif text == "AC":
        self.operations = []  # Clear the list.
    elif text == "=":
        self.evaluate()
    self.label["text"] = "".join(self.operations)

def evaluate(self):
    try:
        self.operations = [str(eval("".join(self.operations)))]
    except (ArithmeticError, SyntaxError, TypeError, NameError):
        self.operations = ["ERROR"]

此代码不能只是粘贴到您的程序中，而只是为了演示如何解决问题。

Python Tkinter GUI计算器

1 个答案: