Python 3：使用 %s 和 .format()
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Python 3: using %s and .format()
提问by Zaur Nasibov
I have finally switched from %to the .format()string formatting operator in my 2.x code in order to make it easier to migrate to 3.x in future. It was a bit surprising to find out that not only the %-style formatting remains in Py3, but it is widely used in the standard library code. It seems logical, because writing '(%s)' % variableis a bit shorter and maybe easier to comprehend than '({})'.format(variable). But I'm still in doubt. Is it proper (pythonic?) to use both approaches in the code?
Thank you.
我终于在我的 2.x 代码中从字符串格式化操作符切换%到了.format()，以便将来更容易迁移到 3.x。发现不仅%在 Py3 中保留了-style 格式，而且在标准库代码中广泛使用它，这有点令人惊讶。这似乎合乎逻辑，因为写作'(%s)' % variable比'({})'.format(variable). 但我仍然怀疑。在代码中使用这两种方法是否合适（pythonic？）？谢谢你。
采纳答案by Vlad
Python 3.2 documentation said that, %will eventually go away.
Python 3.2 文档说，%最终会消失。
http://docs.python.org/3.2/tutorial/inputoutput.html#old-string-formatting
http://docs.python.org/3.2/tutorial/inputoutput.html#old-string-formatting
Since
str.format()is quite new, a lot of Python code still uses the%operator. However, because this old style of formatting will eventually be removed from the language,str.format()should generally be used.
由于
str.format()它很新，很多 Python 代码仍然使用%运算符。但是，因为这种旧的格式样式最终会从语言中删除，所以str.format()一般应该使用。
But as @regilero says, the sentence is gone from 3.3, which might suggest it's not actually the case. There are some conversations herethat suggest the same thing.
但正如@regilero 所说，这句话从 3.3 中消失了，这可能表明情况并非如此。有一些谈话这里暗示了同样的事情。
As of Python 3.4 the paragraph 7.1.1reads:
从Python 3.4 开始，第 7.1.1 段内容如下：
The % operator can also be used for string formatting. It interprets the left argument much like a sprintf()-style format string to be applied to the right argument, and returns the string resulting from this formatting operation.
% 运算符也可用于字符串格式化。它将左参数解释为很像要应用于右参数的 sprintf() 样式格式字符串，并返回此格式化操作产生的字符串。
回答by Guy with 6 Magikarps.
"%s" is now "{}", so insted of adding %s replace it with {} where you would want to add the variable into the string.
“%s”现在是“{}”，因此添加 %s 将其替换为 {}，您希望将变量添加到字符串中。
def main():
n="Python 3.+"
l="looks nice"
f="does not look practical."
print("This seems to be the new way {}".format(n)\
+ "will be working, rather than the ' % ',{} but {}".format(l,f))
main()
#In comparison to just injecting the variable
Output disregard the quotes they are for illustration reasons
出于说明原因，输出忽略它们的引号
"This seems to be the new way "Python 3.+" will be working, rather than the '%;, "looks nice" but "does not look practical.""
“这似乎是“Python 3.+”的新工作方式，而不是 '%;，“看起来不错”但“看起来不实用”。
