Python全局文件

Question

如何寫入函數內的全局文件？

實施例：

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() 

上面的代碼不工作。它說「ValueError：關閉文件上的I/O操作」 有什麼想法？

Answer 1

write_to_file是一個函數，

嘗試

def write_to_file(): 

othrwise代碼是罰款

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'] 

它總是在需要的時候更好地打開一個文件，而不是在開始時開啓劇本。
使用with可確保在退出前關閉所有文件處理程序。