Python - 第一个单词未包含在搜索中

Question

为什么第一个单词正在打印，但未包含在“dic”的搜索中。

谁能告诉我原因和解决方案如何也包含第一个单词？

这是我的代码:

my_dic = {
"a":"1", 
"b":"2", 
"c":"3", 
"d":"4", 
"e":"5", 
}

with open('c:\\english_text_file.txt',encoding = 'utf8') as file :
  for line in file:
    for word in line.split():
      print('word from line.split: ',word)
      if word in my_dic.keys():
       print('word from if word in ...',word)

and the test file is here:

文本文件的内容是:

a b c d e

输出代码为:

word from line.split:  a
word from line.split:  b
word from if word in ... b
word from line.split:  c
word from if word in ... c
word from line.split:  d
word from if word in ... d
word from line.split:  e
word from if word in ... e

Answer 1

这是因为Windows对于txt文件的一个行为:它会添加BOM到 txt 文件的开头。

什么是BOM ？

这意味着Byte-order mark Description ，取值如下:

Byte-order mark Description 
EF BB BF UTF-8 
FF FE UTF-16 aka UCS-2, little endian 
FE FF UTF-16 aka UCS-2, big endian 
00 00 FF FE UTF-32 aka UCS-4, little endian. 
00 00 FE FF UTF-32 aka UCS-4, big-endian.

打开您的english_text_file.txt ，然后使用任何十六进制编辑器查看它，您将看到内容是:

efbb bf61 2062 2063 2064 2065 0d0a

在这里，efbb bf是 BOM，61 2062 2063 2064 2065 0d0a的 ASCII 码是 a b c d e\r\n

所以对于utf-8文件，我们需要检查它是否有BOM开始时，如果有，需要将其删除。

接下来是一个示例代码供您引用，如果您不介意更改原始文件，也可以直接覆盖旧的输入文件，这里我只是使用一个不带 BOM 的新文件。就在其中。

import codecs

my_dic = {
    "a":"1",
    "b":"2",
    "c":"3",
    "d":"4",
    "e":"5",
}

content = open('./english_text_file.txt', 'rb').read()
if content[:3] == codecs.BOM_UTF8:
    content = content[3:]
    open('./changed_english_text_file.txt', 'wb').write(content)
else:
    open('./changed_english_text_file.txt', 'wb').write(content)

with open('./changed_english_text_file.txt',encoding = 'utf8') as file :
    for line in file:
        for word in line.split():
            print('word from line.split: ',word)
            if word in my_dic.keys():
                print('word from if word in ...',word)

输出是:

word from line.split:  a
word from if word in ... a
word from line.split:  b
word from if word in ... b
word from line.split:  c
word from if word in ... c
word from line.split:  d
word from if word in ... d
word from line.split:  e
word from if word in ... e