升压正则表达式中的链接器错误

Question

我想在 boost lib 中学习一些关于正则表达式的知识，我尝试编译这个简单的示例代码：

// regex_search example
#include <iostream>
#include <string>
#include <boost/regex.hpp>

int main ()
{
  std::string s ("this subject has a submarine as a subsequence");
  boost::smatch m;
  boost::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 (boost::regex_search (s,m,e)) {
    for (auto x:m) std::cout << x << " ";
    std::cout << std::endl;
    s = m.suffix().str();
  }

  return 0;
}

我使用：g++ -std=c++0x -I /usr/lib/boost/include -L /usr/lib/boost/lib -lboost_regex test_regex.cpp

但是 g++ 给我看：

/tmp/ccjni2je.o: In function `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)':
test_regex.cpp:(.text._ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j[boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)]+0x22): undefined reference to `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)'
/tmp/ccjni2je.o: In function `bool boost::regex_search<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, char, boost::regex_traits<char, boost::cpp_regex_

还有更多...

谁能帮帮我？

Answer 1

三件事：

1. Boost.Regex 库很可能称为libboost_regex<b>-mt</b>。
2. 除非您知道 Boost 库是使用 C++11 支持编译的，否则您应该删除
   -std=c++0x 选项。
3. 您应该始终将 LIBS 放在末尾，因为 GNU ld 按照目标文件和 LIBS 在命令行中出现的顺序来解析符号。

试试：

g++ -I /usr/lib/boost/include -L /usr/lib/boost/lib test_regex.cpp -lboost_regex-mt