C++ Extract number from the middle of a string

Question

I have a vector containing strings that follow the format of text_number-number

Eg: Example_45-3

Answer 1

Check this out

std::string ex = "Example_45-3";
int num;
sscanf( ex.c_str(), "%*[^_]_%d", &num );

Answer 2

Using @Pixelchemist's answer and e.g. std::stoul:

bool getFirstNumber(std::string const & a_str, unsigned long & a_outVal)
{
    auto pos = a_str.find_first_of("0123456789");

    try
    {
        if (std::string::npos != pos)
        {
            a_outVal = std::stoul(a_str.substr(pos));

            return true;
        }
    }
    catch (...)
    {
        // handle conversion failure
        // ...
    }

    return false;
}