Entry.get（）不返回用户输入的值

Question

我试图用python编写一个数值积分程序，但是在使用Entry.get()时，有些用户输入并没有存储为变量。如何正确使用Entry.get()

我对编码是相当陌生的，我正在尝试创建一个计算数值积分的程序。集成的代码是自己工作的，但是我尝试使用tkinter库来创建用户界面。我在给定行中得到以下错误：

finalValue = ((a-b)/n)*initialValue

ZeroDivisionError: float division by zero

由此我意识到用户值没有存储在变量中，因此n、a和b都返回零。我通过在用户输入之后打印变量来验证这一点。我想我用错了Entry.get()，但我不知道怎么用。我也看过类似的问题和解决方案，但似乎都不管用

    def integrateNumerical(n, b, a):

        def f(x): #Defines the function to be integrated
             return eval(numericalFunction)

        initialValue = 0 #Sets the initial iterative value
        finalValue = 0 #Sets the final iterative value

        for i in range(1, n+1):
            initialValue = initialValue + f(b+((i-(1/2))*((a-b)/n)))

        finalValue = ((a-b)/n)*initialValue

    return finalValue

    def integrateNumericalWindow():

        window8 = Toplevel(window)
        window8.title("Numerical Integration")
        window8.geometry("400x400")

        iterationNumber = IntVar()
        upperBound = IntVar()
        lowerBound = IntVar()
        functionNumerical = StringVar()

        Label(window8, text = "").pack()
        Label(window8, text = "Number of iterations: ").pack()
        iterationNumberEntry = Entry(window8, textvariable = iterationNumber)
        iterationNumberEntry.pack()

        Label(window8, text = "").pack()
        Label(window8, text = "Upper bound: ").pack()
        upperBoundEntry = Entry(window8, textvariable = upperBound)
        upperBoundEntry.pack()

        Label(window8, text = "").pack()
        Label(window8, text = "Lower bound: ").pack()
        lowerBoundEntry = Entry(window8, textvariable = lowerBound)
        lowerBoundEntry.pack()

        Label(window8, text = "").pack()
        Label(window8, text = "Function: ").pack()
        functionNumericalEntry = Entry(window8, textvariable = functionNumerical)
        functionNumericalEntry.pack()

        global n
        global a
        global b
        global numericalFunction

        n = int(Entry.get(iterationNumberEntry))
        a = float(Entry.get(upperBoundEntry))
        b = float(Entry.get(lowerBoundEntry))
        numericalFunction = str(Entry.get(functionNumericalEntry))

        Label(window8, text = "").pack()
        Button(window8, text = "Integrate", width = 10, height = 1, bd = "0", fg = "#383a39", bg = "#a1dbcd", command = lambda : integrateNumerical(n, b, a)).pack()

Answer 1

def integrateNumerical(n, b, a):

    def f(x): #Defines the function to be integrated
         return eval(numericalFunction)

    initialValue = 0 #Sets the initial iterative value
    finalValue = 0 #Sets the final iterative value

    for i in range(1, n+1):
        initialValue = initialValue + f(b+((i-(1/2))*((a-b)/n)))

    finalValue = ((a-b)/n)*initialValue

    return finalValue

def integrateNumericalWindow():

    window8 = tk.Toplevel()
    window8.title("Numerical Integration")
    window8.geometry("400x400")

    iterationNumber = tk.IntVar()
    upperBound = tk.IntVar()
    lowerBound = tk.IntVar()
    functionNumerical = tk.StringVar()

    tk.Label(window8, text = "").pack()
    tk.Label(window8, text = "Number of iterations: ").pack()
    iterationNumberEntry = tk.Entry(window8, textvariable = iterationNumber)
    iterationNumberEntry.pack()

    tk.Label(window8, text = "").pack()
    tk.Label(window8, text = "Upper bound: ").pack()
    upperBoundEntry = tk.Entry(window8, textvariable = upperBound)
    upperBoundEntry.pack()

    tk.Label(window8, text = "").pack()
    tk.Label(window8, text = "Lower bound: ").pack()
    lowerBoundEntry = tk.Entry(window8, textvariable = lowerBound)
    lowerBoundEntry.pack()

    tk.Label(window8, text = "").pack()
    tk.Label(window8, text = "Function: ").pack()
    functionNumericalEntry = tk.Entry(window8, textvariable = functionNumerical)
    functionNumericalEntry.pack()

    global n
    global a
    global b
    global numericalFunction

    n = int(tk.Entry.get(iterationNumberEntry))
    a = float(tk.Entry.get(upperBoundEntry))
    b = float(tk.Entry.get(lowerBoundEntry))
    numericalFunction = str(tk.Entry.get(functionNumericalEntry))

    tk.Label(window8, text = "").pack()
    tk.Button(window8, text = "Integrate", width = 10, height = 1, bd = "0", fg = "#383a39", bg = "#a1dbcd", command = lambda : integrateNumerical(n, b, a)).pack()
    window8.mainloop()

用法：

import tkinter as tk
integrateNumericalWindow()

Answer 2

get（）是由Entry创建的对象的方法。您可以如下所示调用它作为对象的方法

n = int(iterationNumberEntry.get())
a = float(upperBoundEntry.get())
b = float(lowerBoundEntry.get())
numericalFunction = str(functionNumericalEntry.get())

你的例子不完整，所以我无法测试。你需要包括

window8.mainloop()

4个get可能需要包含在积算中。然后单击按钮时它们将运行

HTH公司

编辑：阅读评论后作进一步解释

我试着让它在你上面所做的基础上工作。我不确定它是否符合你的要求

from tkinter import *

def integrateNumericalWindow():

    window8 = Tk()
    window8.title("Numerical Integration")
    window8.geometry("400x400")

    iterationNumber = IntVar()   
    upperBound = IntVar()
    lowerBound = IntVar()
    functionNumerical = StringVar()

    Label(window8, text = "").pack()
    Label(window8, text = "Number of iterations: ").pack()
    iterationNumberEntry = Entry(window8, textvariable = iterationNumber)
    iterationNumberEntry.pack()

    Label(window8, text = "").pack()
    Label(window8, text = "Upper bound: ").pack()
    upperBoundEntry = Entry(window8, textvariable = upperBound)
    upperBoundEntry.pack()

    Label(window8, text = "").pack()
    Label(window8, text = "Lower bound: ").pack()
    lowerBoundEntry = Entry(window8, textvariable = lowerBound)
    lowerBoundEntry.pack()

    Label(window8, text = "").pack()
    Label(window8, text = "Function: ").pack()
    functionNumericalEntry = Entry(window8, textvariable = functionNumerical)
    functionNumericalEntry.pack()

    Label(window8, text = "").pack()

    Label(window8, text="Result :").pack()
    result=Label(window8, text="None")
    result.pack()

    # I've moved the command function to here so it can 'see' all the variables it needs
    def integrateNumerical():
        # The 4 Entry widgets are read in this function when the button is clicked.
        n = int(iterationNumberEntry.get())
        a = float(upperBoundEntry.get())
        b = float(lowerBoundEntry.get())
        numericalFunction = str(functionNumericalEntry.get())

        def f(x): #Defines the function to be integrated
            return eval(numericalFunction)

        print(n, a, b, numericalFunction, f(3.0) )

        initialValue = 0 #Sets the initial iterative value
        finalValue = 0 #Sets the final iterative value

        for i in range(1, n+1):
            initialValue = initialValue + f(b+((i-(1/2))*((a-b)/n)))

        finalValue = ((a-b)/n)*initialValue

        result.configure(text=str(finalValue)) # Set a label with the result instead of returning a result.
        # return finalValue

    Button(window8, text = "Integrate", width = 10, height = 1, bd = "0", fg = "#383a39", 
    bg = "#a1dbcd", command=integrateNumerical).pack()

    window8.mainloop()

integrateNumericalWindow()

我希望这能澄清我的意思