#include <iostream>
#include "regex"
using namespace std;
std::string str = R"( <HTML>< META HTTP - EQUIV = \"CONTENT-TYPE\" CONTENT=\"TEXT/HTML;CHARSET=UTF-8\">\r\n\t<META HTTP-EQUIV=\"X-UA-COMPATIBLE\" CONTENT=\"IE=EDGE\">)";
std::regex r(R"(<\s*META[^>]+/?>)");
{
获得以后剩下的任务就是字符串查找提取编码了