ValueError: int() 以 10 为基数的无效文字:''
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【中文标题】ValueError: int() 以 10 为基数的无效文字:\'\'【英文标题】:ValueError: invalid literal for int() with base 10: ' 'ValueError: int() 以 10 为基数的无效文字:'' 【发布时间】:2017-12-06 12:51:08 【问题描述】:我是 python 新手,这是我从事的第一个项目,它是一个莱特币 - 欧元转换程序。我有一个问题,如果我没有在程序的 Entry() 字段中输入任何内容并提交它,控制台将输出以下错误消息(因为 int() 和 float() 无法将空字符串转换为 int/一个浮点数):
Exception in Tkinter callback
Traceback (most recent call last):
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1536, in __call__
return self.func(*args)
File "/Users/Samir/Library/Mobile Documents/com~apple~CloudDocs/Coding/Python/hello_world/exch.py", line 13, in exchange
choice = int( exc.get() ) # choice of EUR to LTC or other way around
ValueError: invalid literal for int() with base 10: ''
我在这件事上使用的整个代码:
from Tkinter import *
from json import *
from urllib2 import *
def exchange():
data = urlopen('https://btc-e.com/api/3/ticker/ltc_eur') # EUR - LTC API
j_obj = load(data) #loads json data
exch = float( j_obj['ltc_eur']['avg'] ) # picks exchange rate out of api
choice = int( exc.get() ) # choice whether EUR to LTC or other way around
amount = float ( am.get() ) # amount of the currency the user wants to convert
if choice == 0:
print round((1 / exch) * amount, 2), "Litecoins"
elif choice == 1:
print round(exch * amount, 2), "Euro"
else: # if something other than 0 or 1 was typed in
print "I'm sorry but you have to enter either 0 or 1"
am.delete(0, END)
exc.delete(0, END)
master = Tk() # creates new window in var master
master.wm_title("LTC - EUR converter") # creates title for the window
Label(master, text = "EUR into LTC (0) or LTC into EUR(1): ").grid(row = 0, sticky = W) # creates choice string in a table (Row 1)
Label(master, text = "Amount: ").grid(row = 1, sticky = E) # creates text "Amount" in a table (Row 1)
exc = Entry(master) # picks up Entryvalue
exc.grid(row = 0, column = 1)
am = Entry(master) # picks up Entryvalue
am.grid(row = 1, column = 1) # places it at row 0 colum 1 in the table
Button(master, text = "Quit", command = master.quit).grid(row = 2, column= 1, sticky = W) # creates a quit button that closes the window
Button(master, text = "Submit", command = exchange).grid(row = 2, column = 1) # creates a submit button that executes def "exchange"
mainloop() # starts the program
我设法通过将 if 查询更改为将输入与字符串进行比较并在确认已输入 0 或 1 后将输入转换(为 int 和 float)来解决问题。 修改后的代码:
choice = exc.get()
amount = am.get()
if choice == '0':
choice = int(choice)
amount = float(amount)
print round((1 / exch) * amount, 2), "Litecoins"
elif choice == '1':
choice = int(choice)
amount = float(amount)
print round(exch * amount, 2), "Euro"
else:
print "I'm sorry but you have to enter either 0 or 1"
所以我的问题是,对于这个问题有没有更有效的解决方案?因为我认为我的方法可行,但它不是最好的选择。
【问题讨论】:
【参考方案1】:"It is better to ask for forgiveness than permission".
您可以将代码放在try-except
块中。
try:
choice = int(choice)
amount = float(amount)
except ValueError:
print "I'm sorry but you have to enter either 0 or 1"
return
if choice == 1:
...
else:
...
这样,您检查choice
的值一次而不是两次。
编辑:如果为choice
和amount
保留单独的try-except
大括号是明智的。在当前情况下,输入有效的choice
但无效的amount
可能会产生误导性错误消息。
【讨论】:
你可能想概括一下。如果您在选择中输入零或一但将金额留空,您将收到误导性错误消息。 tkinter 验证输入的快速 google 将向您展示执行此操作的标准方法。 @Mic 谢谢,添加脚注。以上是关于ValueError: int() 以 10 为基数的无效文字:''的主要内容,如果未能解决你的问题,请参考以下文章
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