Is there are more elegant way to convert a two state string into a bitset then just by a for loop

I wrote this code snippet to convert a two state string ("+++–+-" or "yynnny") into a bitset:

#include <bitset>
#include <cstddef>
#include <string>
#include <iostream>


std::bitset<70> convertTwoStateString(std::string twoState)
{
    std::bitset<70> a{0b0};
    std::bitset<70> eins{0b1};

    for(const auto c : twoState)
    {
        if(c == '+')
        {
            a <<= 1;
            a |= eins;
        }
        if(c == '-')
        {
            a <<= 1; 
        }
    }
    return a; 
}


int main()
{

    std::string s{"-+--+++--+--+"};
    std::bitset<70> set = convertTwoStateString(s);

    std::cout << set << std::endl;
    //0000000000000000000000000000000000000000000000000000000000100111001001

    return 0;
}

I wonder if there is a more algorithmic/elegant way to do such a conversion.

>Solution :

The std::bitset constructor can specify alternate characters representing 0/1, so you can

std::string s{"-+--+++--+--+"};
std::bitset<70> set(s, 0, s.size(), '-', '+');

Demo