Entry.get() 不返回用户输入的值

Question

我正在尝试在Python中编码一个数值集成程序，但是使用Entry.get()时，某些用户输入并不作为变量存储。如何正确使用Entry.get()？

我是编码的新手，我正在尝试创建一个计算数值集成的程序。集成的代码可以独立存在，但是我试图使用TKINTER库制作用户界面。我在给定行中遇到以下错误：

finalValue = ((a-b)/n)*initialValue
ZeroDivisionError: float division by zero

由此我意识到用户值未存储在变量中，因此n，a和b都返回零。我通过在用户输入后打印变量来验证这一点。我认为我错误地使用了Entry.get()，但是我不确定如何使用。我也看过类似的问题和解决方案，但它们似乎都没有用。

    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

get（）是条目创建的对象的一种方法。您将其称为以下作为对象的方法。

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

您的示例还不完整，因此我无法对此进行测试。您需要包括

window8.mainloop()

4可能需要包含在IntegrateNumerical中。然后，他们将在单击按钮时运行。

hth

编辑：阅读评论后进一步说明

我试图根据您上面的工作来使其起作用。我不确定它可以做你想要的。

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()

我希望这能阐明我的意思。

Answer 2

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()