Unsigned Binary String to Unsigned Binary Integer

I have created a working Getter that :

Returns the stored decimal value as an unsigned binary string bits wide

string GetUnsignedBase2(int base_10, int bits) {

string base_2;
//Find binary
int remainder = 0;
for (int i = 0; i != bits; i++) {
    remainder = base_10 % 2;
    base_2.insert(0, to_string(remainder));
    base_10 /= 2;

}
return base_2;

But now I am trying to create a Setter for it that :

Updates the value of the stored decimal integer by interpreting the parameter base 2 as an unsigned binary integer

I am unsure how to do this, so far I have:

void BaseConverter::SetUnsignedBase2(string base_2)
{

}