在字符串格式化期间，并非所有参数都已转换 [英] Not all of arguments converted during string formatting

问题描述

我正在编写一个脚本，该脚本将当前日期和时间保存为文件名，但是我收到一条错误消息，指出 TypeError：不是在格式化字符串时转换了所有参数，我是Python新手，可能错过了一些明显的东西。下面的代码：

Im wrtiting a script which saves the current date and time as a filename but I get an error stating "TypeError: not all arguments converted during string formatting" I am new to Python andmay of missed something obvious. Code below:

from subprocess import Popen
import datetime

today = datetime.date.today()

today = str(today)

print today

f = open("%s.sql", "w" % (today))
x =  Popen(["mysqldump", "-u", "root", "-pucsdrv", "normalisationtion"], stdout = f)
x.wait()
f.close()

推荐答案

字符串格式错误的位置；它必须在要格式化的字符串之后：

You're putting the string formatting in the wrong place; it needs to be right after the string that's being formatted:

f = open("%s.sql" % (today), "w")

合法的做法是不传递任何格式参数，就像对<$ c所做的一样$ c>％s.sql ，但是传递参数但传递正确的值（ w％（今天））是不合法的传递了一个，但是 w 中没有字符串格式，因此您得到一个错误，指出并非所有参数都已使用）

It's legal to not pass any formatting arguments, like you did with "%s.sql", but it's not legal to pass arguments but not the right amount ("w" % (today) passes one, but there's no string formatting in "w", so you get an error that not all of the arguments were used)

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