python学习-读写文件

#!/usr/bin/env python
#encoding=utf-8

import os

#os.linesep代表一个换行符
#window下是'\r\n',unix下是'\n'
ls = os.linesep

def readFile():
fname = raw_input('Enter a filename: ')

print

try:
fobj = open(fname,'r')
except IOError, e:
print '*** file open error:',e
else:
for eachLine in fobj:
#print eachLine.rstrip('\n')
#rstrip('\n')可以把字符串右侧所有的'\n'删除
#print eachLine.lstrip('x')#可以把字符串左侧所有的字符x删除
#strip('\n ')可以把字符串两端所有的'\n'和空格删除
print eachLine,
fobj.close()

def writeFile():

while True:
#<python核心编程>52页好像少写了下面这一行代码
#这本书第一个demo就这么大个疏漏,实在不应该
fname = raw_input('Enter a filename: ')
if os.path.exists(fname):
print 'error: %s already exists' % fname
else:
break

all = []
print '\nEnter lines (. by itself to quit).\n'

while True:
entry = raw_input('>')
if entry == '.':
break
else:
all.append(entry)

fobj = open(fname,'w')
fobj.writelines(['%s%s' % (x,ls) for x in all])
fobj.close()

print 'DOWN!'

if __name__ == '__main__':
while True:
want = raw_input('what you want?\n\'w\':write,\'r\':read :')
if want == 'w':
writeFile()
break
elif want == 'r':
readFile()
break
else:
continue