使用__repr __()了解双引号和单引号之间的区别 [英] Understanding difference between Double Quote and Single Quote with __repr__()

问题描述

print，object和repr()有什么区别? 为什么要以不同的格式打印?

What is the difference between print, object, and repr()? Why is it printing in different formats?

请参见output difference:

>>> x="This is New era"
>>> print x             # print in double quote when with print()
This is New era

>>> x                   #  x display in single quote
'This is New era'

>>> x.__repr__()        # repr() already contain string
"'This is New era'"

>>> x.__str__()         # str() print only in single quote ''
'This is New era'

推荐答案

'和"之间没有语义差异.如果字符串包含"(反之亦然)，则可以使用'，Python也会这样做.如果字符串中包含这两个字符串，则必须转义其中的某些字符串(或使用三引号"""或'''). (如果同时使用'和"，则Python和许多程序员似乎更喜欢'.)

There is no semantic difference between ' and ". You can use ' if the string contains " and vice versa, and Python will do the same. If the string contains both, you have to escape some of them (or use triple quotes, """ or '''). (If both ' and " are possible, Python and many programmers seem to prefer ', though.)

>>> x = "string with ' quote"
>>> y = 'string with " quote'
>>> z = "string with ' and \" quote"
>>> x
"string with ' quote"
>>> y
'string with " quote'
>>> z
'string with \' and " quote'

关于print，str和repr:print将打印给定的字符串，且不带附加引号，而str将创建给定对象的字符串(在这种情况下为字符串本身)和repr 从对象创建一个表示字符串"(即，包含一组引号的字符串).简而言之，str和repr之间的区别应该在于str对于用户来说容易理解 和repr对于Python来说易于理解的 >.

About print, str and repr: print will print the given string with no additional quotes, while str will create a string from the given object (in this case, the string itself) and repr creates a "representation string" from the object (i.e. the string including a set of quotes). In a nutshell, the difference between str and repr should be that str is easy to understand for the user and repr is easy to understand for Python.

此外，如果您在交互式外壳程序中输入任何表达式，Python会自动回显结果的repr.这可能有点令人困惑:在交互式Shell中，当您执行print(x)时，您看到的是str(x)；使用str(x)时，看到的是repr(str(x))，使用repr(x)时，看到的是repr(repr(x))(因此双引号).

Also, if you enter any expression in the interactive shell, Python will automatically echo the repr of the result. This can be a bit confusing: In the interactive shell, when you do print(x), what you see is str(x); when you use str(x), what you see is repr(str(x)), and when you use repr(x), you see repr(repr(x)) (thus the double quotes).

>>> print("some string") # print string, no result to echo
some string
>>> str("some string")   # create string, echo result
'some string'
>>> repr("some string")  # create repr string, echo result
"'some string'"

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