整型
In [1]: a = 1
In [2]: print(a)
1
In [3]: type(a)
Out[3]: int
浮点型
In [4]: b = 1.2
In [5]: type(b)
Out[5]: float
字符串类型
In [6]: c = westos
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-6-47a30bc3df16> in <module>
----> 1 c = westos
NameError: name 'westos' is not defined
In [7]: c = 'westos'
In [8]: type(c)
Out[8]: str
类型转换
In [9]: float(a)
Out[9]: 1.0
In [10]: int(b)
Out[10]: 1
In [11]: float(c)
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-11-36b90e4449a0> in <module>
----> 1 float(c)
ValueError: could not convert string to float: 'westos'
In [12]: str(a)
Out[12]: '1'
In [13]: str(b)
Out[13]: '1.2'
In [14]: d = '123456'
In [15]: int(d)
Out[15]: 123456
In [16]: float(d)
Out[16]: 123456.0
如何删除内存中的变量
In [17]: del a
In [18]: a
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-18-3f786850e387> in <module>
----> 1 a
NameError: name 'a' is not defined
bool类型
bool:只有两个值(True False)
非0即真
In [19]: a = 1
In [20]: bool(a)
Out[20]: True
In [21]: bool(0)
Out[21]: False
In [22]: bool(1)
Out[22]: True
In [23]: bool('')
Out[23]: False
In [24]: bool(' ')
Out[24]: True
In [25]: bool(2412414)
Out[25]: True
运算符号
先乘除后加减
同级运算符是从左至右 计算
可以使用()调整计算的优先级
In [26]: 1+2
Out[26]: 3
In [27]: 3-1
Out[27]: 2
In [28]: 2*3
Out[28]: 6
In [29]: 6/3
Out[29]: 2.0
In [30]: 9/2 # " / " 表示浮点数除法，返回浮点结果;
Out[30]: 4.5
In [31]: 9//2 #" // " 表示整数除法,返回不大于结果的一个最大的整数
Out[31]: 4
In [32]: 9%2
Out[32]: 1
In [33]: 2**2
Out[33]: 4
