小费计算器 - 语法错误
大家好，我对编程还比较陌生，但我正在尝试用图形界面来制作一个小费计算器。这个项目不大，也不算太难，但我遇到了一些错误。奇怪的是，我的Python没有显示错误信息。它只是跳到命令行，显示“SyntaxError”（语法错误），然后又回到脚本里。之前是可以显示错误的，但我不知道现在怎么了……总之，如果你们能帮我解决这个问题，我会非常感激的。
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# A tip calculator
# A tip calculator using a GUI interface
# Austin Howard Aug - 13 - 2014
from tkinter import *
#Creating buttons.
class Calculator(Frame):
""" A GUI tip calculator."""
def __init__(self, master):
Frame.__init__(self, master)
self.grid()
self.creating_buttons()
def creating_buttons(self):
"""This list includes Entry fields, which the user will use to define
several objects such as Bill, and how many people are paying on that bill."""
#Create an entry field button for how much the bill total is.
#Create a label
bill_lbl = Label(self,
text = "Bill: ")
bill_lbl.grid(row = 1,
column = 0,
columnspan = 1,
sticky = W)
#Create an Entry field.
bill_ent = Entry(self)
bill_ent.grid(row = 1,
column = 1,
sticky = W)
#Create a Button for how many people will be paying on the bill
#Create label
people_paying_lbl = Label(self,
text = "How many people are paying on this bill?: ")
people_paying_lbl.grid(row = 2,
column = 0,
columnspan = 1,
sticky = W)
#Create an entry field
people_paying_ent = Entry(self)
people_paying_ent.grid(row = 2,
column = 1,
sticky = W)
#Create a text box to display the totals in
bill_total_txt = Text(self,
width = 40,
height = 40,
wrap = WORD)
bill_total_txt.grid(row = 3,
column = 0,
columnspan = 2,
sticky = W)
#Create a Submit button
submit = Button(self,
text = "Submit",
command = self.total)
submit.grid(row = 4,
column = 0,
sticky = W)
def total(self):
""" Takes the values from Bill, and # of people to get the amount that will be
displayed in the text box."""
TAX = .15
bill = float(bill_ent)
people = people_paying_ent
Total = ("The tip is: $", TAX * bill, "\nThe total for the bill is: $",
TAX * bill + bill,
"divided among the people paying equally is: $",
TAX * bill + bill / people "per, person.")
bill_total_txt.delete(0.0, END)
bill_total_txt.insert(0.0, Total)
#Starting the Program
root = Tk()
root.title("Tip Calculator")
app = Calculator(root)
root.mainloop()
`
2 个回答
0
你获取输入框内容的方式不对。你应该把一个字符串变量绑定到这些输入框上，这样才能在后面获取用户输入的内容：
self.billvar = StringVar()
bill_ent = Entry(self, textvariable = self.billvar)
人数输入框也是同样的道理。然后在你的 total 函数里，你可以通过 self.billvar.get() 来读取这些值。你可以用 float(self.billvar.get()) 把这个值转换成浮点数。不过，如果转换失败了（比如用户输入了不能转换成浮点数的内容），你可能想要告诉他们，而不是让程序报错。所以你应该使用类似这样的代码：
try:
convert input
except:
what to do if it fails, tell the user?
else:
what to do if it did not fail, so do the calculations
这样你的程序就变成了这样（我加了注释，标记为 ##）：
# A tip calculator
# A tip calculator using a GUI interface
# Austin Howard Aug - 13 - 2014
from tkinter import *
#Creating buttons.
class Calculator(Frame):
""" A GUI tip calculator."""
def __init__(self, master):
Frame.__init__(self, master)
self.grid()
self.creating_buttons()
def creating_buttons(self):
"""This list includes Entry fields, which the user will use to define
several objects such as Bill, and how many people are paying on that bill."""
#Create an entry field button for how much the bill total is.
#Create a label
bill_lbl = Label(self,
text = "Bill: ")
bill_lbl.grid(row = 1,
column = 0,
columnspan = 1,
sticky = W)
#Create an Entry field.
## Create a StringVar and link it to the entry box
self.billvar = StringVar()
bill_ent = Entry(self, textvariable = self.billvar)
bill_ent.grid(row = 1,
column = 1,
sticky = W)
#Create a Button for how many people will be paying on the bill
#Create label
people_paying_lbl = Label(self,
text = "How many people are paying on this bill?: ")
people_paying_lbl.grid(row = 2,
column = 0,
columnspan = 1,
sticky = W)
#Create an entry field
## Create a StringVar and link it to the entry box
self.pplvar = StringVar()
people_paying_ent = Entry(self, textvariable = self.pplvar)
people_paying_ent.grid(row = 2,
column = 1,
sticky = W)
#Create a text box to display the totals in
## This had to be self.bill_total_txt, to be able to put text in it from the total function
self.bill_total_txt = Text(self,
height = 10,
width = 40,
wrap = WORD)
self.bill_total_txt.grid(row = 3,
column = 0,
columnspan = 2,
sticky = W)
#Create a Submit button
submit = Button(self,
text = "Submit",
command = self.total)
submit.grid(row = 4,
column = 0,
sticky = W)
def total(self):
""" Takes the values from Bill, and # of people to get the amount that will be
displayed in the text box."""
TAX = .15
## Try to convert the bill to a float and the number of people to an integer
try:
bill = float(self.billvar.get())
people = int(self.pplvar.get())
## If something goes wrong tell the user the input is invalid
except:
self.bill_total_txt.delete(0.0, END)
self.bill_total_txt.insert(0.0, 'Invalid input')
## If the conversion was possible, calculate the tip, the total amount and the amout per person and format them as a string with two decimals
## Then create the complete message as a list and join it togeather when writing it to the textbox
else:
tip = "%.2f" % (TAX * bill)
tot = "%.2f" % (TAX * bill + bill)
tot_pp = "%.2f" % ((TAX * bill + bill) / people)
Total = ["The tip is: $", tip,
"\nThe total for the bill is: $",
tot,
" divided among the people paying equally is: $",
tot_pp,
" per person."]
self.bill_total_txt.delete(0.0, END)
self.bill_total_txt.insert(0.0, ''.join(Total))
#Starting the Program
root = Tk()
root.title("Tip Calculator")
app = Calculator(root)
root.mainloop()
1
你在第68行有个错误：
把
TAX * bill + bill / people "per, person.")
替换成
TAX * bill + bill / people, "per, person.")
另外，确保在root.mainloop()后面去掉反引号。