#_*_coding:utf-8_*_ #课堂练习1     # print('start....')     # while True:     #     name =input('Please enter your name:')     #     pwd = input('please enter your pwd:')     #     if name == 'egon' and pwd == '123':     #         print('login successful')     #     else:     #         print('user or pwd err')     # print('end...')     # print('start..')     # tag = True     # while tag:     #     name = input('please your name>>:')     #     pwd = input('Please your pwd>>:')     #     if name == 'oOC' and pwd =='123':     #         print('login successful')     #         tag = False     #     else:     #         print('usr or pwd err')     #     # print('end..') #课堂练习2 break 强行终止本层循环     # count = 1     # while count < 6:     #     print(count)     #     count+=1     # count = 1     # while True:     #     if count > 5:     #         break     #     print(count)     #     count += 1     # print('star...')  #输入错误一直输     # while True:     #     name = input('Please your name>>:')     #     pwd = input('Please your password>>:')     #     if name == 'oOC' and pwd == '123':     #         print('login successful')     #         break     #     else:     #         print('usr or pwd err')     #     # print('end ...')     # print('star...')     # count = 0     # while True:     #     if count == 3 :     #         print('输错次数太多')     #         break     #     name = input('Please your name>>:')     #     pwd = input('Please your pwd>>:')     #     #     if name == 'egon' and pwd == '123':     #         print('login successful')     #         break     #     else:     #         print('user or pwd err')     #         count +=1     # print('end...') #打印0-10     # count = 0     # while count <= 10:     #     print('loop',count)     #     count +=1 #打印0-10之间的偶数     # count = 0     # while count <= 10:     #     if count%2 == 0:     #         print('loop',count)     #     count += 1 #打印0-10之间的奇数     # count = 0     # while count <= 9:     #     if count%2 ==1:     #         print('loop',count)     #     count +=1 #死循环     # import time     # num = 0     # while True:     #     print('count', num)     #     time.sleep(1)     #     num+=1 #循环嵌套与tag # name='egon' # password='123' # # while True: #     inp_name=input('用户名: ') #     inp_pwd=input('密码: ') #     if inp_name == name and inp_pwd == password: #         while True: #             cmd=input('>>: ') #             if not cmd:     #cmd输入为假是 not cmd 为真 进行continue #                 continue #             if cmd == 'quit': #                 break #             print('run <%s>' %cmd) #     else: #         print('用户名或密码错误') #         continue #     break #tag # name='egon' # password='123' # # tag=True # while tag: #     inp_name=input('用户名: ') #     inp_pwd=input('密码: ') #     if inp_name == name and inp_pwd == password: #         while tag: #             cmd=input('>>: ') #             if not cmd:continue #             if cmd == 'quit': #                 tag=False #                 continue #             print('run <%s>' %cmd) #     else: #         print('用户名或密码错误') #使用while循环输出1 2 3 4 5 6   8 9 10     # count = 0     # while count < 10:     #     count += 1     #     if count == 7:     #         continue     #     print(count) #求1-100内的所有数的和     # count = 1     # sum = 0     # while count <=100:     #     sum = sum + count     #     count += 1     # print(sum) #输出1- 100内的所有奇数     # count = 1     # while count < 100:     #     if count % 2 == 1:     #         print(count)     #     count += 1 #输出1- 100内的所有偶数     # count = 1     # while count <= 100:     #     if count % 2 == 0:     #         print(count)     #     count += 1 #求1-2+3-4+5 ... 99的所有数的和     # tag = 1     # count = 1     # sum = 0     # while count <= 99:     #     sum = sum + tag * count     #     tag *= -1     #     count += 1     # print(sum) #用户登陆（三次机会重试）     # name = 'oOC'     # password = '123'     # count = 1     # while count <= 3:     #     in_name=input('Please enter your name:')     #     in_pass=input('Please enter your password:')     #     #     if in_name == name and in_pass == password:     #         print('login success')     #         break     #     #     print('username or password is not correct!')     #     count += 1     # name = 'oOC'     # password = '123'     # count = 1     # tag = True     # while tag:     #     if count <= 3:     #         in_name = input('Please enter your name:')     #         in_pass=input('Please enter your password:')     #         if in_name == name and in_pass == password:     #             print('login success')     #             break     #         else:     #             print('username or password is not correct!')     #             count += 1     #     else:     #         print('login failed!')     #         tag = False #猜年龄     # num = 31     #     # count = 1     # while count <= 3:     #     guess_num = input('Please enter the num:')     #     guess_num = int(guess_num)     #     if guess_num == num:     #         print('Correct!')     #         break     #     else:     #         print('Wrong！Please try again!')     #     count += 1     # else:     #     print('foolish!') #猜年龄升级版     # num = 31     # count = 1     #     # while count < 4:     #     guess_num = input('Please enter the num:')     #     guess_num = int(guess_num)     #     count +=1     #     if guess_num == num:     #         print('Correct!')     #         break     #     elif count == 4:     #         tag = input('Could u play the game again?[Y/N]')     #         if tag == 'Y':     #             count = 1     #         else:     #             break     #     else:     #         print('Wrong！Please try again!')