Python之路四

一、算术运算符

int，float数字类型

# print(10 + 3.1)
# print(10 / 3)
# print(10 // 3)
# print(10 % 3)
# print(10 ** 2)

# +与*(了解)
# msg1='hello'
# msg2='world'
# print(msg1 + msg2)
# print(msg1*10)

# l1=['a','b']
# l2=['c','d']
# print(l1 + l2)
# print(l1*3)

2、赋值运算符

（1）增量赋值

例一、age=18

age+=1 #age=age + 1

print(age)

例二、age=18

age*=3 #age=age*3

print(age)

   (2)交叉赋值

x=11

y=12

x,y=y,x

print(x,y)

  (3)链式赋值

x=y=z=10

print(x,y,z)

  (4)解压赋值

1、列表的解压符值

l=['egon',18,'male',33333]
 a=l[0]
 b=l[1]
 c=l[2]
 d=l[3]

a,b,c,d=l
 print(a,b,c,d)

 a,b,c,d=l

 salaries=[1.1,2.2,3.3,4.4,5.5]
 a,b,_,_,_=salaries
 a,b,*_=salaries
 *_,a,b=salaries
 a,*_,b=salaries
 print(a,b)

2. 字典的解压赋值
 dic={'aaa':1,'bbb':2,'ccc':3}
 x,y,z=dic
 print(x,y,z)

 3 逻辑运算符
 and: 左右两个条件必须同时成立，最终结果才为True
 print(10 < 3 and 3 == 3)

 or: 左右两个条件只要有一个成立，最终结果就为True
 print(10 < 3 or 3 == 3)
 print(10 < 3 or 3 < 3)

 not:将紧跟其后的条件结果取反
 print(not 10 > 3)
 print(not 10 < 3 or 3 < 3)

 res=(10 > 3 and 3 == 1) or ((4 < 3 and True) or (not 1 > 2 or 3 > 2))

print(res)

4、 比较运算符
# ==
 print(10 != 3)

 msg1='abcdef'
 msg2='abcz'

print(msg2 > msg1)

l1=[1,'aaa',333]
l2=[2,'b']
print(l2 > l1)

二、流程控制之if判断：

#语法一:
# if 条件:
# 代码1
# 代码2
# 代码3

# gender='female'
# age=18
# is_beautiful=True
#
# if gender == 'female' and age > 16 and age < 20 and is_beautiful:
# print('开始表白。。。。')
#
# print('其他代码')

#语法二:
# if 条件:
# 代码1
# 代码2
# 代码3
# else:
# 代码1
# 代码2
# 代码3

# gender='female'
# age=26
# is_beautiful=True
#
# if gender == 'female' and age > 16 and age < 20 and is_beautiful:
# print('开始表白。。。。')
# else:
# print('阿姨好')
#
# print('其他代码')

#语法三:
# if 条件1:
# if 条件2:
# 代码1
# 代码2
# 代码3

# gender='female'
# age=18
# is_beautiful=True
# is_successfull=True
#
# if gender == 'female' and age > 16 and age < 20 and is_beautiful:
# print('开始表白。。。。')
# if is_successfull:
# print('在一起，，，')
# else:
# print('逗你玩呢。。。')
# else:
# print('阿姨好')
#
# print('其他代码')
#

#语法四:
# if 条件1:
# 代码1
# 代码2
# 代码3
# elif 条件2:
# 代码1
# 代码2
# 代码3
# elif 条件3:
# 代码1
# 代码2
# 代码3
# .......
# else:
# 代码1
# 代码2
# 代码3

'''
如果：成绩>=90，那么：优秀

如果成绩>=80且<90,那么：良好

如果成绩>=70且<80,那么：普通

其他情况：很差
'''

score=input('your score: ')
score=int(score)

if score >= 90:
print('优秀')
elif score >= 80:
print('良好')
elif score >= 70:
print('普通')
else:
print('很差')

三、流程控制之while循环

# 引入：
# name='egon'
# pwd='123'
#
# inp_name=input('your name: ')
# inp_pwd=input('your password: ')
# if inp_name == name and inp_pwd == pwd:
# print('login successfull')
# else:
# print('name or password error')
#
# inp_name=input('your name: ')
# inp_pwd=input('your password: ')
# if inp_name == name and inp_pwd == pwd:
# print('login successfull')
# else:
# print('name or password error')
#
# inp_name=input('your name: ')
# inp_pwd=input('your password: ')
# if inp_name == name and inp_pwd == pwd:
# print('login successfull')
# else:
# print('name or password error')
#
#循环就是重复做某件事
# 语法：
# while 条件:
# 代码1
# 代码2
# 代码3

# while True:
# 1+1

# n=1
# while n < 10:
# print(n)
# n+=1

# name='egon'
# pwd='123'
#
# tag=True
# while tag:
# inp_name=input('your name: ')
# inp_pwd=input('your password: ')
# if inp_name == name and inp_pwd == pwd:
# print('login successfull')
# tag=False
# else:
# print('name or password error')

# while+break:终止本层循环
name='egon'
pwd='123'

while True:
inp_name=input('your name: ')
inp_pwd=input('your password: ')
if inp_name == name and inp_pwd == pwd:
print('login successfull')
break
else:
print('name or password error')