一 python与用户的交互
1 如何交互
可以通过input()和print()来实现简单的交互，input()方法的作用只是接收值,无论我们输入的值是任何类型，input()接收的都是字符串。
input('name:')
input('age:')
name:einsam
age:18
'18'
2 python2的input和raw_input
python2的raw_input就是python3的input
python2中的input与用户交互时必须得用户指定输入内容的数据类型，现在python写的程序都是与用户交互，所以它没有存在的必要了。
二 格式化输出
1 占位符
用逗号进行字符串拼接非常麻烦，这时候就需要用到占位符 %s 和 %d
name = input('name:')
age = input('age:')
print ('my name is %s,my age is %s '% (name,age))
name:einsam
age:11
my name is einsam,my age is 11
2 format格式化
name = input('name:')
age = input('age:')
print('my name is {}, my age is {}'.format(name,age))
name:einsam
age:11
my name is einsam, my age is 11
name = input('name:')
age = input('age:')
print('my name is {0}, my age is {1}'.format(name,age))
name:einsam
age:11
my name is einsam, my age is 11
name = input('name:')
age = input('age:')
print('my name is {name}, my age is {age}'.format(name=name,age=age))
name:einsam
age:11
my name is einsam, my age is 11
3 f-String格式化
name = input('name:')
age = input('age:')
print(f'my name is {name}, my age is {age}')
name:einsam
age:11
my name is einsam, my age is 11
f大小写都是可以的
三 基本运算符
1 算数运算符
1+1
2
1-1
0
1*1
1
1/1
1.0
1//1
1
2 比较运算符
1>1
False
1<1
False
1!=1
False
1>=1
True
1<=1
True
3 赋值运算符
x = 1
print(x)
1
4 逻辑运算符
and or not
2 > 1 and 3 > 2
True
2 > 1 or 1 > 2
True
not 2 > 1
True
5 身份运算符
is 比较的是 id
x = 10
y = 10
print(x is y)
print(x == y)
True
True
x = 1000
y = 1000
print(x is y)
print(x == y)
False
True
x = 100
y = 10
print(x is y)
print(x == y)
False
False
id相同的值一定相同，值相同的id不一定相同，小整数池的除外
6 python运算优先级
想要优先级高的，用括号括起来就行了
7 链式赋值
x = 1
y = 1
z = 1
print(x,y,z)
1 1 1
x = y = z
print(x,y,z)
1 1 1
7 交叉赋值
x = 10
y = 11
z = x
x = y
y = z
print(x,y)
11 10
8 解压缩
解压缩就是把多个值一次性拿出来
有时候我们解压缩的值可能是我们不想要的，那么可以使用下划线，万能的下划线。
name_list = ['nick', 'egon', 'jason', 'tank', 'kevin', 'jerry']
x, y, _, _, _, z = name_list
print(x,y,z)
nick egon jerry
*_可以省略多个我们不需要的值
name_list = ['nick', 'egon', 'jason', 'tank', 'kevin', 'jerry']
x, y, *_, z = name_list
print(x,y,z)
nick egon jerry