Python核心编程——第四章Python对象-优快云博客

本文介绍三种方法来判断Python中变量的数值类型，包括使用isinstance、两次调用type及导入types模块的方式，并提供了具体示例。

三种方法查看数字数据的类型：

[1] isinstance 可读性更好
#! /usr/bin/env python '''typechk.py''' def displayNumType(num): print num, 'is', if isinstance(num, (int, long, float, complex)): print 'a number of type:', type(num).__name__ else: print 'not a number at all!' displayNumType(-69) displayNumType(99999999999999999999L) displayNumType(99999999999999999999) displayNumType(98.6) displayNumType(-5.2+1.9j) displayNumType('aaa') ####### # output ####### -69 is a number of type: int 99999999999999999999 is a number of type: long 99999999999999999999 is a number of type: long 98.6 is a number of type: float (-5.2+1.9j) is a number of type: complex aaa is not a number at all!

[2] 调用两次type

#! /usr/bin/env python '''typechk.py''' def displayNumType(num): print num, 'is', if type(num)==type(0): print 'an integer' elif type(num)==type(0L): print 'a long' elif type(num)==type(0.0): print 'a float' elif type(num)==type(0+0j): print 'a complex number' else: print 'not a number at all!' displayNumType(-69) displayNumType(99999999999999999999L) displayNumType(99999999999999999999) displayNumType(98.6) displayNumType(-5.2+1.9j) displayNumType('aaa') ####### # output ####### -69 is an integer 99999999999999999999 is a long 99999999999999999999 is a long 98.6 is a float (-5.2+1.9j) is a complex number aaa is not a number at all!

[3] import types

#! /usr/bin/env python import types '''typechk.py''' def displayNumType(num): print num, 'is', if type(num)==types.IntType: print 'an integer' elif type(num)==types.LongType: print 'a long' elif type(num)==types.FloatType: print 'a float' elif type(num)==types.ComplexType: print 'a complex number' else: print 'not a number at all!', print 'but, it is', if type(num)==types.StringType: print 'a string' displayNumType(-69) displayNumType(99999999999999999999L) displayNumType(99999999999999999999) displayNumType(98.6) displayNumType(-5.2+1.9j) displayNumType('aaa') ####### # output ####### -69 is an integer 99999999999999999999 is a long 99999999999999999999 is a long 98.6 is a float (-5.2+1.9j) is a complex number aaa is not a number at all! but, it is a string