>>> float(3)3.0>>> float(‘4.2‘)4.2
>>> str(4)‘4‘>>> str(4.3345)‘4.3345‘
>>> int(‘5‘)5>>> int(5.89)5>>> round(5.89)6>>> round(5.5)6>>> round(4.5)4
>>> int(‘5.3‘)Traceback (most recent call last):File "<pyshell#20>", line 1, in <module>int(‘5.3‘)ValueError: invalid literal for int() with base 10: ‘5.3‘>>>
原文：http://www.cnblogs.com/fange666/p/4676582.html