Python全局文件

Question

如何写入函数内的全局文件？

实施例：

output_file=open("output_file_name.txt", "w") 

def write_to_file:  
    global output_file  
    output_file.write('something') 

write_to_file() 

output_file.close() 

上面的代码不工作。它说“ValueError：关闭文件上的I/O操作” 有什么想法？

Answer 1

write_to_file是一个函数，

尝试

def write_to_file(): 

othrwise代码是罚款

Answer 2

>>> output_file = "output_file" 
>>> def write_to_file(): 
...  global output_file 
...  with open(output_file,"w") as f: 
...   f.write("I wrote to file") 
...  with open(output_file, "r") as f: 
...   print f.readlines() 
>>> write_to_file() 
    ['I wrote to file'] 

它总是在需要的时候更好地打开一个文件，而不是在开始时开启剧本。
使用with可确保在退出前关闭所有文件处理程序。