一个程序学会python的流程控制

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:~$