使用正则表达式查找字符串错误

Question

不能理解为何这样一个这个的代码就会报函数已删除的错误

#include <iostream>
#include <string>
#include <regex>

using namespace std;

int main()
{
    regex r;
    try {
        r.assign("[[:alnum:]]+\\.(cpp|cxx|cc)$", regex::icase);
    }catch(regex_error e)
    {
        cout << e.what() << "\ncode: " << e.code() << endl;
    }
    smatch results;
    if (regex_search(string("myfile.cc"), results, r))
        cout << results.str() << endl;
}

但是下面这样的代码就可以正常查找，有没有人知道原因为何？

#include <iostream>
#include <string>
#include <regex>

using namespace std;

int main()
{
    regex r;
    try {
        r.assign("[[:alnum:]]+\\.(cpp|cxx|cc)$", regex::icase);
    }catch(regex_error e)
    {
        cout << e.what() << "\ncode: " << e.code() << endl;
    }
    smatch results;
    string s = "myfile.cc";
    if (regex_search(s, results, r))
        cout << results.str() << endl;
}

Answer 1

string参数为右值的regex_search()函数在声明时被标为delete了. 编译器的设置.

#if _LIBCPP_STD_VER > 11
template <class _ST, class _SA, class _Ap, class _Cp, class _Tp>
bool
regex_search(const basic_string<_Cp, _ST, _SA>&& __s,
             match_results<typename basic_string<_Cp, _ST, _SA>::const_iterator, _Ap>&,
             const basic_regex<_Cp, _Tp>& __e,
             regex_constants::match_flag_type __flags = regex_constants::match_default) = delete;
#endif