当“variable_names”返回多个结果时，为什么index的值总是为零？

Question

我想计算每个正则表达式搜索结果对一个文件。我相信我正在填充一个列表，然后通过尝试获取计数器的值来循环。

for file in XDTS: 
    data_tag_regex = re.compile(r'data_tag=\"(.*?)\"') 
    if file.endswith('.xdt'): 
     xdt_file = open(file, 'r') 
     for line in xdt_file: 
      variable_names = data_tag_regex.findall(line) 
      for index, variable_name in enumerate(variable_names): 
       print(index) 

Answer 1

你必须每行一个匹配和多行匹配。你enumerate()呼叫从0每次开机，因为这是每个新线新的呼叫：

for line in xdt_file: 
    # per line, find matches 
    variable_names = data_tag_regex.findall(line) 
    # for *this line only* print the indices, counting from 0 
    for index, variable_name in enumerate(variable_names): 
     print(index) 

如果你想在所有行保持索引每场比赛，你需要独立数：

index = 0 
for line in xdt_file: 
    variable_names = data_tag_regex.findall(line) 
    for variable_name in variable_names: 
     index += 1 
     print(index)