笨办法17更多文件操作

源代码如下:

 1 from sys import argv
 2 from os.path import exists
 3 
 4 script, from_file, to_file = argv
 5 
 6 print "Copying from %s to %s" % (from_file, to_file)
 7 
 8 # We could do these two on one line too, how?
 9 input = open(from_file)
10 
11 
12 indata = open(from_file).read()
13 
14 print "The input file is %d bytes long" % len(indata)
15 
16 print "Does the output file exist? %r" % exists(to_file)
17 print "Ready, hit RETURN to continue, CTRL-C to abort."
18 raw_input()
19 
20 output = open(to_file, 'w')
21 output.write(indata)
22 
23 print "Alright, all done."
24 
25 output.close()
26 input.close()

运行结果：
这里写图片描述

加分习题2，写成一行，代码如下：

 1 from sys import argv
 2 
 3 script, from_file, to_file = argv
 4 
 5 """
 6 in_file = open(from_file)
 7 indata = in_file.read()
 8 out_file = open(to_file, 'w')
 9 out_file.write(indata)
10 """
11 
12 open(to_file, 'w').write(open(from_file).read())

但是没弄明白为啥下面这种写法就不用close

20170916 学习22课时问了师父，因为open的返回值没有变量接收，用完就释放了，所以不需要close，有点理解，还要再继续消化一下！