python核心编程第六章第八题

题目：使用列表，编写将0~1000范围的数字翻译为英文的程序，例如输入89，输出eighty-nine。

#!/usr/bin/env python
'''numbers to english'''

#for less than 21
list1=['zero','one','two','three','four','five','six','seven','eight','nine',
       'ten','eleven','twelve','thirteen','fourteen','fifteen','sixteen',
       'seventeen','eighteen','nineteen','twenty']
#for second bit
list2=['','','twenty','thirty','forty','fifty',
       'sixty','seventy','eighty','ninety','hundred']
#for 1000
list3=['','one thousand']

#filter th input
def num_input():
    while True:
        num=raw_input('Enter a number in 0~1000: ')
        num=num.strip()
        if num=='':
            print 'no value'
            continue
        try:
            num2=int(num)
        except Exception:
            print 'TypeError'
            continue
        if num2<0 or num2>1000:
            print 'over range'
        else:
            break
    return num

#translate number to english
def translate(num):
    n1=int(num)
    if n1<21 and n1>=0: #one word
        r1=list1[n1] #use index
        return r1
    elif n1>20 and n1<100: #use second bit
        n2=repr(n1) #to string
        r2=list2[int(n2[-2])] #the second bit
        r3=list1[int(n2[-1])] #the first bit
        if int(n2[-1])==0: #only second bit and first bit is 0
            return r2
        else:
            return r2+'-'+r3
    elif n1>=100 and n1<1000: #use third bit
        n3=repr(n1)
        r4=list1[int(n3[-3])] #the third bit
        r5=list2[int(n3[-2])] #the second bit
        r6=list1[int(n3[-1])] #the first bit
        if int(n3[-1])==0 and int(n3[-2])!=1: #first is 0
            return r4+' hundred-'+r5
        elif int(n3[-2])==1:
            r7=list1[int(n3[-2:])] #sec+fir less than 20,only use list1
            return r4+' hundred-'+r7
        else:
            return r4+' hundred-'+r5+'-'+r6
    elif n1==1000:
        r8=list3[1] #use fourth
        return r8

if __name__=='__main__': #main()
    print translate(num_input())

测试记录：
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 0
zero
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 1
one
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 13
thirteen
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 311
three hundred-eleven
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 721
seven hundred-twenty-one
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 899
eight hundred-ninety-nine
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: 1000
one thousand
[root@ahqz py]# python num-to-english.py
Enter a number in 0~1000: a
TypeError
Enter a number in 0~1000: b
TypeError
Enter a number in 0~1000:
no value
Enter a number in 0~1000: 666
six hundred-sixty-six
[root@ahqz py]#