python写文件时出问题

异常代码如下：
write a file error: [Errno 2] No such file or directory: 'C:\x0cile.txt'

Traceback (most recent call last):
  File "C:\Documents and Settings\USER\桌面\复件 test.py", line 84, in <module>
    test()
  File "C:\Documents and Settings\USER\桌面\复件 test.py", line 78, in test
    writefile(s)
  File "C:\Documents and Settings\USER\桌面\复件 test.py", line 59, in writefile
    f.write(str(string))
UnboundLocalError: local variable 'f' referenced before assignment


Python code:

。。。。。。。。。。。

def writefile(string):
strfile="C:\file.txt"
try:
f = open(strfile,'a')
except IOError,e:
print "write a file error:",e

f.write(str(string))
f.close()



def test():
fname = 'C:\ZLLKDoc.cpp'
#raw_input('Enter filename: ')
try:
fobj = open(fname, 'r')
except IOError, e:
print "*** file open error:", e
strFile=fobj.read()

fobj.close()

s = eraser(strFile)
print s





实在不知道哪里错了，请大侠们帮忙看看，感激不尽

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test（） 函数中第一行加入 global f
然后你的两个函数的逻辑