a="aA1一bB2二cC3三dD4四eE5五fF6六gG7七hH8八iI9九"
"""
分行输出为:
abcdefghi
ABCDEFGHI
123456789
一二三四五六七八九
"""
 
print("方法一:===============")
for r in range(0,4):
 t=''
 for s in range(0+r,len(a),4):
  t=t+a[s]
 print(t)
 
print("方法二:===============")
 
#=_=这个方法会不会看起来比较傻"方法3:回字有N种写法===============")
import string
ta=tb=tc=td=''
la=string.ascii_lowercase
ua=string.ascii_uppercase
nb=string.digits
ub="一二三四五六七八九"
for s in a:
 if s in la:
  ta=ta+s
 if s in ua:
  tb=tb+s
 if s in nb:
  tc=tc+s
 if s in ub:
  td=td+s
print(ta)
print(tb)
print(tc)
print(td)
 
print("方法4:回字有一种叫做正则的写法===============")
import re
#这正则写法感觉不科学,暂时没有好的想法
reg=["[a-z]","[A-Z]","\d","[^\da-zA-Z]"]
for s in reg: 
 rega=re.compile(s)
 s=re.findall(rega,a)
 print("".join(s))
 
"""
输出:
方法一:===============
abcdefghi
ABCDEFGHI
123456789
一二三四五六七八九
方法二:===============
abcdefghi
ABCDEFGHI
123456789
一二三四五六七八九
方法3:回字有N种写法===============
abcdefghi
ABCDEFGHI
123456789
一二三四五六七八九
方法4:回字有一种叫做正则的写法===============
abcdefghi
ABCDEFGHI
123456789
一二三四五六七八九
"""

f=open("shuju.txt","r")
content=f.read()
print content
for i in content:
  print i
f.close()
f=open('shuju.txt','w')
f.write(content)
f.close()