Question

我打算编写用（123）计算一个数字的程序，并向我显示它们的总和。但我想编写一个代码，按下（总和）按钮时执行此操作：{如果字段没有任何整数类型的数字调用errorMsg函数，否则计算数字}但我不知道我怎么能知道做这个。请帮忙！

from tkinter import *
frame = Tk()
def textBoxes():
    global e1      
    e1 = Entry(frame,justify=LEFT )

def labels():  
    var1 = StringVar()
    var1.set("Enter first number: ")
    label1 = Label(frame, textvariable = var1)
    var3=StringVar()   
def errorMsg():
    msg = messagebox.showinfo("Please Enter Some Number!")      
def calculator():    
    #def __init__(self,String_value1,String_value2,sum_result)
    String_value1 = e1.get()
    Int_value1 = int(String_value1)    

   if not(String_value1.get()):
       errorMsg()
   else:
       sum_result = Int_value1 + 123   

def buttons():
    B1 = Button(frame, text="Sum", command=calculator)

buttons()
labels()
textBoxes()
frame.mainloop()

Answer 1

在您的计算器方法中，不要检查它是否为空，尝试操作您的值并在失败时捕获异常。它被称为Easier to ask for forgiveness than permission。

result = StringVar()
def calculator():  
    try:
        user_input = int(e1.get())   
        result.set(str(user_input+123)) #or however you like to show this
    except ValueError:
        errorMsg()

使用您的代码的小片段：

import tkinter as tk
from tkinter import messagebox

frame = tk.Tk()
var1 = tk.StringVar()
var3 = tk.StringVar()
ent1 = tk.Entry(frame,justify="left")
var1.set("Enter first number: ")
var3.set("Result")

def textBoxes():
    ent1.pack()

def labels():
    tk.Label(frame, textvariable=var3).pack()
    tk.Label(frame, textvariable=var1).pack()

def errorMsg():
    messagebox.showinfo("Error", "Please enter a valid number!")

def calculator():  
    try:
        user_input = int(ent1.get())   
        var3.set("Result = "+str(user_input+123))
    except ValueError:
        var3.set("Please enter a valid number!")
        errorMsg()

def buttons():
    tk.Button(frame, text="Sum", command=calculator).pack()

labels()
textBoxes()
buttons()

frame.mainloop()

如果输入框为空，如何在{if}语句中调用函数？

1 个答案: