1. 算术运算
print(10 / 3)
print(10 // 3)
print(10 ** 2)
2. 赋值运算
增量赋值
age=18
age+=1
age=age + 1
print(age)
age=18
age/=3
age=age/3
print(type(age))
age**=2
age=age**2
交叉赋值
x=10
y=20
temp=x
x=y
y=temp
print(x,y)
链式赋值
x=10
y=x
z=y
x=y=z=10
print(id(x))
print(id(y))
print(id(z))
解压赋值
l=[1.2,2.2,3.3,4.4,5.5]
a=l[0]
b=l[1]
c=l[2]
d=l[3]
e=l[4]
a,b,c,d,e=l
a,b,c,d,e,f=l
a,b,c,d=l
print(a,b,c,d,e)
l=[1.2,2.2,3.3,4.4,5.5]
a,b,*_=l
print(a,b)
a,*_,b=l
print(a,b)
*_,a,b=l
print(a,b)
流程控制之while循环
基本语法:
while 条件:
代码1
代码2
代码3
...
示范
name_of_bk='egon'
pwd_of_bk='123'
tag=True
while tag:
inp_name=input('your name>>: ')
inp_pwd=input('your password>>: ')
if inp_name == name_of_bk and inp_pwd == pwd_of_bk:
print('login successful')
tag=False
else:
print('username or password error')
print('other code...')
II: while+break:break代表结束本层循环
示范：
while True:
print(1)
break
print(2)
print(3)
name_of_bk='egon'
pwd_of_bk='123'
while True:
inp_name=input('your name>>: ')
inp_pwd=input('your password>>: ')
if inp_name == name_of_bk and inp_pwd == pwd_of_bk:
print('login successful')
break
else:
print('username or password error')
print('other code......')
III: while + continue: continue代表结束本次循环，直接进入下一次
示范
count=1
while count < 6:
if count == 3:
count+=1
continue
print(count)
count+=1
输错三次退出
name_of_bk='egon'
pwd_of_bk='123'
count=0
while True:
if count == 3:
print('输错的次数过多。。。')
break
inp_name=input('your name>>: ')
inp_pwd=input('your password>>: ')
if inp_name == name_of_bk and inp_pwd == pwd_of_bk:
print('login successful')
break
else:
print('username or password error')
count+=1 #count=3 输错3次
IV:while + else
count=0
while True:
if count == 10:
break
print(count)
count+=1
else:
print("else的子代块只有在while循环没有被break打断的情况下才会执行")
count=0
while count <= 10:
print(count)
count+=1
else:
print("else的子代块只有在while循环没有被break打断的情况下才会执行")
name_of_bk='egon'
pwd_of_bk='123'
count=0
tag=True
while tag:
if count == 3:
print('输错的次数过多。。。')
break
inp_name=input('your name>>: ')
inp_pwd=input('your password>>: ')
if inp_name == name_of_bk and inp_pwd == pwd_of_bk:
print('login successful')
while tag:
print("""
0 退出
1 购物
2 支付
3 查看购物
""")
cmd=input('>>>: ')
if cmd == '0':
tag=False
continue
if cmd == '1':
print('购物。。。。。。。')
elif cmd == '2':
print('支付。。。。。')
elif cmd == '3':
print('查看购物车')
else:
print('输入错误的指令')
else:
print('username or password error')
count+=1 #count=3 输错3次