流程控制之判断,while循环,for循环

Posted 2020-11-09 Chillwave

流程控制之判断

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

# 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 条件:
#     代码1
#     代码2
#     代码3
#     ...
# else:
#     代码1
#     代码2
#     代码3
#     ...

# 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 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
is_success=False

if cls == ‘human‘ and sex == ‘female‘ and age > 16 and age < 22:
    print(‘开始表白...‘)
    if is_success:
        print(‘在一起‘)
    else:
        print(‘我逗你玩呢....‘)
else:
    print(‘阿姨好‘)

print(‘end....‘)

流程控制之while循环

#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 successfull‘)
#     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



# 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‘)

流程控制之for循环

 

# 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‘
# #     print(k,info[k])
#
# for item in names:
#     print(item)


# for i in range(1,10):
#     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
#     print(i)

# names=[‘egon‘,‘asb‘,‘wsb‘,‘lsb‘,‘csb‘]
# for i in range(len(names)):
#     print(i,names[i])

# for i in range(5):
#     print(‘========>第一层: %s<=========‘ %i)
#     for j in range(3):
#         print(‘          第二层: %s‘ %j)


#for+break
# names=[‘asb‘,‘wsb‘,‘egon‘,‘lsb‘,‘csb‘]
# for n in names:
#     if n == ‘egon‘:
#         break
#     print(n)

#for+continue
# 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‘:
    #     break
    print(n)
else:
    print(‘=====>‘)