创建example.txt，编写程序只将大小写字母转换，其余不变动。

with open(filename) as f:
    con=f.read().swapcase()
with open(filename,'w') as f1:
    f1.write(con)

with open('example.txt','r') as f:
    ff = f.read().swapcase()
    f.close()
f1=open("result.txt","w")
f1.write(ff)
f1.close()

要找到路径