E记法:
15000 : 1.5e4 : 1.5乘以10的四次方
>>> a = 0.0000000000000000000000000025
>>> print(a)
2.5e-27
>>> 2.5e-27
2.5e-27
>>> 15e10
150000000000.0
>>> 15e4
150000.0
类型转换 :int()--str()--float()
>>> a='520'
>>> b=float(a)
>>> b
520.0
>>> a=520
>>> b=float(a)
>>> b
520.0
>>> a=5.99
>>> b=str(a)
>>> b
'5.99'
>>> c=str(5e19)
>>> c
'5e+19'
类型信息:type()
>>> a='520'
>>> type(a)
<class 'str'>
>>> type(5.4)
<class 'float'>
>>> type(True)
<class 'bool'>
>>> type(5e15)
<class 'float'>
isinstance() 返回boolean类型,true 两个参数类型一直,false 两个参数类型不一致
>>> a="xiao jia"
>>> isinstance(a,str)
True
>>> isinstance(a,int)
False
>>> isinstance(a,bool)
False
>>> isinstance(123,bool)
False
>>> isinstance(123,int)
True
>>> isinstance(True,bool)
True