.//knownface\Aaron_Eckhart_0001.jpg
提取Aaron_Eckhart,即\和_000之间的字符
尝试方法:
regex qq_reg("[.\\s\\S]*?(?=000)");
smatch result;
//std::regex qq_reg("(?<=\\)[.\\s\\S]*?(?=_000)");
if (regex_match(known_face[i], result, qq_reg))
{
for (auto it = result.begin(); it != result.end(); ++it)
cout << *it << endl;
}