流程控制（if、while、for）

#####if判断#######

 

#语法1：if.....语句

# if 条件:

#     代码1

#     代码2

#     代码3

#     ...

#例如：

# cls='human'

# sex='female'

# age=18

#

# if cls == 'human' and sex == 'female' and age > 16 and age < 22:

#     print('开始表白')

#

# print('end....')

#

#

# 语法2：if......else....语句

# if 条件:

#     代码1

#     代码2

#     代码3

#     ...

# else:

#     代码1

#     代码2

#     代码3

#     ...

#例如：

# cls='human'

# sex='female'

# age=38

#

# if cls == 'human' and sex == 'female' and age > 16 and age < 22:

#     print('开始表白')

# else:

#     print('阿姨好')

#

# print('end....')

# 语法3

#if.....elif......elif.....else....

# 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='73'

# score=int(score) #score=73

# if score >= 90:

#     print('优秀')

# elif score >= 80:

#     print('良好')

# elif score >= 70:

#     print('普通')

# else:

#     print('很差')

#

# user_from_db='egon'

# pwd_from_db='123'

#

# user_from_inp=input('username>>>: ')

# pwd_from_inp=input('password>>>: ')

#

# if user_from_inp == user_from_db and pwd_from_inp == pwd_from_db:

#     print('login successfull')

# else:

#     print('user or password error')

#

#if的嵌套

#

# cls='human'

# sex='female'

# age=18

#

# if cls == 'human' and sex == 'female' and age > 16 and age < 22:

#     print('开始表白...')

#     is_success = False

#     if is_success:

#         print('在一起')

#     else:

#         print('我逗你玩呢....')

# else:

#     print('阿姨好')

#

# print('end....')

#while语法,while循环又称为条件循环

# while 条件:

#     code1

#     code2

#     code3

#     ....

# user_db='egon'

# pwd_db='123'

#

# while True:

#     inp_user=input('username>>: ')

#     inp_pwd=input('password>>: ')

#     if inp_user == user_db and inp_pwd == pwd_db:

#         print('login success')

#     else:

#         print('user or password error')

#2 while+break:break的意思是终止掉当前层的循环,.执行其他代码

# while True:

#     print('1')

#     print('2')

#     break

#     print('3')

# user_db='egon'

# pwd_db='123'

#

# while True:

#     inp_user=input('username>>: ')

#     inp_pwd=input('password>>: ')

#     if inp_user == user_db and inp_pwd == pwd_db:

#         print('login successfull')

#         break

#     else:

#         print('user or password error')

# print('其他代码')

#3 while+continue:continue的意思是终止掉本次循环,.直接进入下一次循环

#ps:记住continue一定不要加到循环体最后一步执行的代码

# n=1

# while n <= 10: #

#     if n == 8:

#         n += 1 #n=9

#         continue

#     print(n)

#     n+=1 #n=11

# n=1

# while n <= 10:

#     if n == 6:

#         n+=1

#         continue#相当于在6这里延迟了一下

#     print(n)

#     n+=1

while嵌套If

# while True:

#     if 条件1:

#         code1

#         code2

#         code3

#         continue #无意义

#     elif 条件1:

#         code1

#         continue #有意义

#         code2

#         code3

#     elif 条件1:

#         code1

#         code2

#         code3

#         continue #无意义

#     ....

#     else:

#         code1

#         code2

#         code3

#         continue #无意义

#while循环嵌套

# user_db='egon'

# pwd_db='123'

#

# while True:

#     inp_user=input('username>>: ')

#     inp_pwd=input('password>>: ')

#     if inp_user == user_db and inp_pwd == pwd_db:

#         print('login successfull')

#         while True:

#             cmd=input('请输入你要执行的命令: ')

#             if cmd == 'q':

#                 break

#             print('%s 功能执行...' %cmd)

#         break

#     else:

#         print('user or password error')

#

#

# print('end....')

#while+tag

# user_db='egon'

# pwd_db='123'

#

# tag=True

# while tag:

#     inp_user=input('username>>: ')

#     inp_pwd=input('password>>: ')

#     if inp_user == user_db and inp_pwd == pwd_db:

#         print('login successfull')

#         while tag:

#             cmd=input('请输入你要执行的命令: ')

#             if cmd == 'q':

#                 tag=False

#             else:

#                 print('%s 功能执行...' %cmd)

#

#     else:

#         print('user or password error')

#

#

# print('end....')

#while+else (***)

# n=1

# while n < 5:

#     if n == 3:

#         break

#     print(n)

#     n+=1

# else:

#     print('在整个循环结束后,会进行判断:只有while循环在没有被break结束掉的情况下才会执行else中的代码')

# names=['egon','asb','wsb','lsb','csb']

#

# n=0

# while n < len(names):

#     print(names[n])

#     n+=1

#

#

# names=['egon','asb','wsb','lsb','csb']

# info={'name':'egon','age':18,'sex':'male'}

#

# for k in info: #x=''age'; k自动默认索引从0开始且自动加一

#      print(k,info[k])

#

# for item in names:

#     print(item)

#

#

# for i in range(1,10):#顾头不顾尾

#     print(i)

#

# for i in range(10): #默认的起始位置是0

#     print(i)

#

# for i in range(1,10,2): #1 3  5  7  9，，2是步长即后面第二个

#     print(i)

#

# names=['egon','asb','wsb','lsb','csb']

# for i in range(len(names)):

#     print(i,names[i])

#

#for的嵌套

# for i in range(5):

#     print('========>第一层: %s<=========' %i)

#     for j in range(3):

#         print('          第二层: %s' %j)

#

#

# for+break:break用于退出本层的循环

# names=['asb','wsb','egon','lsb','csb']

# for n in names:

#     if n == 'egon':

#         break

#     print(n)

#

# for+continue：退出本次循环，下次循环继续

# names=['asb','wsb','egon','lsb','csb']

# for n in names:

#     if n == 'egon':

#         continue

#     print(n)

#

#

# for+else

# names=['asb','wsb','egon','lsb','csb']

# for n in names:

#     if n == 'egon':

#         continue

#     print(n)

# else:

#     print('=====>')

# ##########################################

# names=['asb','wsb','egon','lsb','csb']

# for i in range(len(names)):

#     print(i,names[i])

#

# msg='hello word'

# print(msg[8:5:-1])