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python isinstance 判断各种类型的小细节

_鱼与渔_ 2022-03-12 阅读 80
pythongnup2p

1. 基本语法

isinstance(object, classinfo)

Return true if the object argument is an instance of the classinfo argument, or of a (direct, indirect or virtual) subclass thereof. Also return true if classinfo is a type object (new-style class) and object is an object of that type or of a (direct, indirect or virtual) subclass thereof. If object is not a class instance or an object of the given type, the function always returns false. If classinfo is neither a class object nor a type object, it may be a tuple of class or type objects, or may recursively contain other such tuples (other sequence types are not accepted). If classinfo is not a class, type, or tuple of classes, types, and such tuples, a TypeError exception is raised.

 

classinfo 处可以是 a class, type, or tuple of classes and types,

如果是 tuple,则满足 tuple 中的任何一个即返回 True

2. 字符串的类型判断。

字符串,分为 str 和 unicode,二者均继承自 basestring

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>>> isinstance(u'3.0'unicode)

True

>>> isinstance('3.0'str)

True

>>> isinstance(u'3.0'str)

False

>>> isinstance(u'3.0'str)

False

>>> isinstance(u'3.0'basestring)

True

>>> isinstance('3.0'basestring)

True

3. 数字的类型判断

数字分为 int 和 float,暂未发现二者共同的有效父类。

可以用 (int, float) tuple 来判断是否为数字(int 或 float)

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>>> isinstance('3', (intfloat))

False

>>> isinstance(3.0, (intfloat))

True

>>> isinstance(3, (intfloat))

True

>>> isinstance(3.0float)

True

>>> isinstance(3.0int)

False

>>> isinstance(3float)

False

>>> isinstance(3int)

True

 

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