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    python中isinstance函数判断各种类型的小细节

    silencementsilencement2019-07-22 09:40:02原创2824

    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

    >>> 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)

    >>> isinstance('3', (int, float))
    False
    >>> isinstance(3.0, (int, float))
    True
    >>> isinstance(3, (int, float))
    True
    >>> isinstance(3.0, float)
    True
    >>> isinstance(3.0, int)
    False
    >>> isinstance(3, float)
    False
    >>> isinstance(3, int)
    True
    专题推荐:isinstance
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