python初级 1 数据类型和变量

一、整数(int)

例：  0 1 2 3 -1 -2 –3

In [31]: print(type(0))

<class 'int'>

In [32]: print(type(1))

<class 'int'>

In [33]: print(type(2))

<class 'int'>

In [34]: print(type(3))

<class 'int'>

In [35]: print(type(-1))

<class 'int'>

In [36]: print(type(-2))

<class 'int'>

In [37]: print(type(-3))

<class 'int'>

二、浮点数（小数）(float)

例：0.0 0.3  15.5 1.0 –1.45

In [39]: print(type(0.0))

<class 'float'>

In [40]: print(type(0.3))

<class 'float'>

In [41]: print(type(15.6))

<class 'float'>

In [42]: print(type(1.0))

<class 'float'>

In [43]: print(type(-1.45))

<class 'float'>

三、字符串(str)

指的是””或是’’里面的内容

例：'2a' "33" "ab\'cd"

In [44]: print(type('2a'))

<class 'str'>

In [45]: print(type(""))

<class 'str'>

In [46]: print(type("ab\'cd"))

<class 'str'>

In [48]: print("2a")

2a

In [49]: print("")

33

In [50]: print("ab\'cd")

ab'cd

如果想表示’或是”时,需要采用转义符\, 如果需要表示\时,在外面加上转义符\

例:"I\'m a boy"  "say \"hello world\""  "print \\"

In [51]: print("I\'m a boy")

I'm a boy

In [52]: print("say \"hello world\"")

say "hello world"

In [53]: print("print \\")

print \

四、布尔值(bool)

例：True, False

In [56]: print(type(True))

<class 'bool'>

In [57]: print(type(False))

<class 'bool'>

五、空值(NoneType)

例：None

In [58]: print(type(None))

<class 'NoneType'>

练习

请打印出以下变量的值：

n = 123

f = 456.789

s1 = 'Hello, world'

s2 = 'Hello, \'Adam\''

s3 = r'Hello, "Bart"'

s4 = r'''Hello, Lisa!'''