创建单个正则表达式，而不是多个表达式

Question

Im trying create a regular expresion which matches strings pushed onto the strings vector. Is it possible to create a single regular expression to match and extract all the "numerical" values?

std::vector<std::string> strings;
strings.push_back("100/2");
strings.push_back("2");
strings.push_back("200/99");
strings.push_back("150/9*0");

std::regex rex1("(\\d{1,3})(\\/(\\d{1,2})(\\*(\\d+)))"); // matches 150/9*0
std::regex rex2("(\\d{1,3})(\\/(\\d{1,2}))"); // matches 200/99
for (size_t k = 0; k < strings.size(); k++)
{
    std::smatch m;
    std::regex_match(strings[k], m, rex1);


    for (size_t i = 0; i < m.size(); i++)
        std::cout << "match " << i << ": " << m[i] << std::endl;
}

Answer 1

^(\\d{1,3})(\\/(\\d{1,2})(\\*(\\d+))?)?$

That makes the second half optional (so that the "2" still matches) and makes the *0 bit optional within the second half.

The $ at the end is necessary so that if the string does contain the optional parts then they will definitely still be matched & captured.