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song@ubuntu:~$ vi ex4.py song@ubuntu:~$ more ex4.py #!/usr/bin/env python #_*_ coding:utf-8 _*_ print_num=input('Which loop do you want to be printed out?:') count=0 while count<30:     if count==print_num:         print 'There you have got the number:',count         choice=raw_input('Do you want to continue the loop?(y/n):')         if choice=='n':             print 'The while loop is broken by break!'             break         else:             print_num=input('Which loop do you want to be printed out?:')             while print_num<=count:                 print '%d has gone,please enter another number!' % print_num                 print_num=input('Which loop do you want to be printed out?:')     else:         print 'Loop:',count     count+=1 else:     print 'The while loop is over normally!' song@ubuntu:~$ song@ubuntu:~$ python ex4.py Which loop do you want to be printed out?:3 Loop: 0 Loop: 1 Loop: 2 There you have got the number: 3 Do you want to continue the loop?(y/n):n The while loop is broken by break! song@ubuntu:~$ song@ubuntu:~$ python ex4.py Which loop do you want to be printed out?:19 Loop: 0 Loop: 1 Loop: 2 Loop: 3 Loop: 4 Loop: 5 Loop: 6 Loop: 7 Loop: 8 Loop: 9 Loop: 10 Loop: 11 Loop: 12 Loop: 13 Loop: 14 Loop: 15 Loop: 16 Loop: 17 Loop: 18 There you have got the number: 19 Do you want to continue the loop?(y/n):y Which loop do you want to be printed out?:16 16 has gone,please enter another number! Which loop do you want to be printed out?:19 19 has gone,please enter another number! Which loop do you want to be printed out?:28 Loop: 20 Loop: 21 Loop: 22 Loop: 23 Loop: 24 Loop: 25 Loop: 26 Loop: 27 There you have got the number: 28 Do you want to continue the loop?(y/n):y Which loop do you want to be printed out?:30 Loop: 29 The while loop is over normally! song@ubuntu:~$ 

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