python isinstance 判断各种类型的简单示例

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,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

# @param python isinstance 判断各种类型的小细节
# @author 编程之家 52php.cn|www.www.52php.cn 

>>> isinstance(u'3.0',unicode)
True
>>> isinstance('3.0',str)
True
>>> isinstance(u'3.0',str)
False
>>> isinstance(u'3.0',basestring)
True
>>> isinstance('3.0',basestring)
True

# End www.52php.cn

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）

# @param python isinstance 判断各种类型的小细节
# @author 编程之家 52php.cn|www.www.52php.cn 

>>> isinstance('3',(int,float))
False
>>> isinstance(3.0,float))
True
>>> isinstance(3,float))
True
>>> isinstance(3.0,float)
True
>>> isinstance(3.0,int)
False
>>> isinstance(3,float)
False
>>> isinstance(3,int)
True

# End www.52php.cn

（编辑：李大同）

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