没有躲过的坑--正则表达式截取字符串

工程中，需要从字符串中匹配出以:开头，并以:结束的字符串。

Google还是百度，很多C++的正则表达式都是通过st::tr1或boost库中使用的，但是我们仅仅用一个小小的功能，就用一个库不是很好的办法。

对的，之前我的博客已经介绍了C++11的新特性-正则表达式。

所以可以不使用其他的库，来完成任务：

std::vector<string> all_sub_string = {};
std::string all_string = "12:wo:sfd:wom::sdf";

std::regex e(":[a-z0-9_+-]+:");//正则规则

const std::sregex_token_iterator end;

for (std::sregex_token_iterator i(all_string .begin(),all_string .end(),e); i != end; ++i)
{
    all_sub_string .push_back(*i);
}

你可能会迷惑，什么是sregex_token_iterator？
不要着急，sregex_token_iterator其实就是字符串 regex_token_iterator 的类型定义。

typedef regex_token_iterator<string::const_iterator> sregex_token_iterator;

上面的方法很简单，就像使用迭代器一样。

其实regex还有其他的查找方法，现在介绍一下regex_search:
Returns whether some sub-sequence in the target sequence (the subject) matches the regular expression rgx (the pattern). The target sequence is either s or the character sequence between first and last,depending on the version used.

直接上代码：

// regex_search example
#include <iostream>
#include <string>
#include <regex>

int main ()
{
  std::string s ("this subject has a submarine as a subsequence");
  std::smatch m;
  std::regex e ("b(sub)([^ ]*)");   // matches words beginning by "sub"

  std::cout << "Target sequence: " << s << std::endl;
  std::cout << "Regular expression: /b(sub)([^ ]*)/" << std::endl;
  std::cout << "The following matches and submatches were found:" << std::endl;

  while (std::regex_search (s,m,e)) {
    for (auto x:m) std::cout << x << " ";
    std::cout << std::endl;
    s = m.suffix().str();
  }

  return 0;
}

输出：

Target sequence: this subject has a submarine as subsequence
Regular expression: /b(sub)([^ ]*)/
The following matches and submatches were found:
subject sub ject
submarine sub marine
subsequence sub sequence