如何从用户那里获取条目？

Question

这是我的全部代码：

import sys
import tkinter as tk
import os

def bowlingspeedcalc ():
        entry = float(mEntry)
        if type(entry) == float:
            speed = 0.01890*3600/entry

            if speed >165:
                Label1 = tk.Label (str(speed) + " kph !!! You don't bowl that fast!!!o_0 ").place (x = 50,y = 50)                             

            elif speed >=140:
                Label2 = tk.Label ("You are a fast bowler,you bowl at: " + str(speed) + " kilometers per hour").place (x = 50,y = 50) 

            elif speed >= 130:
                Label3 = tk.Label ("You are a fast-medium bowler,you bowl at: " + str(speed) + " kilometers per hour").place (x = 50,y = 50)

            elif speed >= 120:
                Label4 = tk.Label ("You are a medium-fast bowler,you bowl at: " + str(speed) + " kilometers per hour").place (x = 50,y = 50)

            elif speed >= 105:
                Label5 = tk.Label ("You are a medium pace bowler,you bowl at: " + str(speed) + " kilometers per hour").place (x = 50,y = 50)

            elif speed < 105 and speed > 60:
                Label6 = tk.Label ("You are a spin bowler,you bowl at: " + str(speed) + " kilometers per hour").place (x = 50,y = 50)

            elif speed <= 60:
                Label7 = tk.Label ("You bowl at: " + str(speed) + " kilometers per hour; you bowl like my grandma!!!").place (x = 50,y = 50)

def forget_page ():
    widgets = [mlabel1,mlabel2,mlabel3,mEntry,mButton]
    for widget in widgets:
        widget.place_forget ()
    bowlingspeedcalc ()


    mGui = tk.Tk()
    mGui.geometry("300x300")
    mGui.title("YourBowlingSpeed")
    mlabel1 = tk.Label (text = "How much time does your ball take to cover the")
    mlabel2 = tk.Label (text = "20m/22yrds ,from the release to crossing ")
    mlabel3 = tk.Label (text = "the stumps?")
    mlabel1.place (x = 20,y = 5)
    mlabel2.place (x = 17,y = 22)
    mlabel3.place (x = 130,y = 39)
    mEntry = tk.Entry()
    mEntry.place (x = 115,y = 56)
    mButton = tk.Button (text = "Calculate",command = forget_page)
    mButton.place (x = 125, y = 73)
    mGui.mainloop()

这是我的代码，我知道问题出在哪里，但我不知道如何解决它。一个命令转到 Bowlingspeedcalc () 并且探针开始没有出现。那是因为 mEntry 不能转换为浮点数，但是有没有办法可以将 mEntry 转换为用户输入的浮点值？任何帮助将不胜感激！

这是错误信息：

Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Python33\lib\tkinter\__init__.py", line 1475, in __call__
return self.func(*args)
File "C:\Python33\Projects\YourBowlingSpeed.py", line 36, in forget_page

bowlingspeedcalc ()
File "C:\Python33\Projects\YourBowlingSpeed.py", line 7, in bowlingspeedcalc
entry = float(mEntry)
TypeError: float() argument must be a string or a number

Answer 1

使用mEntry.get()获取用户提供的文字。所以，bowlingspeedcalc 的第一行应该是：

entry= float(mEntry.get())

另外，我不确定你是如何让mEntry 对bowlingspeedcalc 可见的。它可能是您帖子的格式。或者您可能需要global。