的boost ::标记生成器点分开，还保持空字段 [英] Boost::tokenizer point seperated, but also keeping empty fields

问题描述

我已经看到这个问题和我很相似，但它是不同的，所以请不要标注它是重复的。

I have seen this question and mine is very similar to it, but it is different, so please do not mark it as duplicate.

我的问题是：如何从一个字符串中的空字段？

My question is: How do I get the empty fields from a string?

我有一个像的std ::字符串s =This.is..a.test的字符串; 和我想要得到的字段＆LT;这家＆GT; ＆LT;＆是GT; ＆LT;＆GT; ＆LT; A＆GT; ＆lt;试验方式＆gt;

I have a string like std::string s = "This.is..a.test"; and I want to get the fields <This> <is> <> <a> <test>.

我已经试过也

typedef boost::char_separator<char> ChSep;
typedef boost::tokenizer<ChSep> TknChSep;
ChSep sep(".", ".", boost::keep_empty_tokens);
TknChSep tok(s, sep);
for (TknChSep::iterator beg = tok.begin(); beg != tok.end(); ++beg)
{
  std::cout << "<" << *beg << "> ";
}

但我得到＆LT;这家＆GT; ＆LT;＆GT; ＆LT;＆是GT; ＆LT;＆GT; ＆LT;＆GT; ＆LT;＆GT; ＆LT; A＆GT; ＆lt;试验方式＆gt;

推荐答案

的第二个参数Boost.Tokenizer的<一个href=\"http://www.boost.org/doc/libs/1_55_0/libs/tokenizer/char_separator.htm\"><$c$c>char_separator是 kept_delims 参数。它用于指定一个分隔符，将显示为令牌。原来的code为指定，应保持作为标记。要解决此问题，更改：

The second argument to Boost.Tokenizer's char_separator is the kept_delims parameter. It is used to specify a delimiters that will show up as tokens. The original code is specifying that "." should be kept as a token. To resolve this, change:

ChSep sep(".", ".", boost::keep_empty_tokens);

到

ChSep sep(".", "", boost::keep_empty_tokens);
            // ^-- no delimiters will show up as tokens.

---

下面是一个完整的例子：

---

Here is a complete example:

#include <iostream>
#include <string>
#include <boost/foreach.hpp>
#include <boost/tokenizer.hpp>

int main()
{
  std::string str = "This.is..a.test";
  typedef boost::tokenizer<boost::char_separator<char> > tokenizer;
  boost::char_separator<char> sep(
      ".", // dropped delimiters
      "",  // kept delimiters
      boost::keep_empty_tokens); // empty token policy

  BOOST_FOREACH(std::string token, tokenizer(str, sep))
  {
    std::cout << "<" << token << "> ";
  }
  std::cout << std::endl;
}

其中产生所需的输出：

Which produces the desired output:

<This> <is> <> <a> <test> 

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