Q: Insert into a vector using an insert using lower_bound How do I change CompareByNA to make the insert work, I assume it's wrong for the first element to insert
program: https://onecompiler.com/cpp/3xycp2vju
bool Company::compareByNA(const Company &a, const Company &b)
{
    return a.getNameAddr() < b.getNameAddr();
}
..
if ( binary_search(CompanyNameList.begin(), CompanyNameList.end(), cmp, Company::compareByNA) )
    {       
        CompanyNameList.insert(lower_bound(CompanyNameList.begin(), CompanyIDList.end(), cmp, Company::compareByNA), cmp); 
        return true;
    }
    return false;
}

for example this not work for other elements that I want to insert in order
if(CompanyNameList.size() == 0)
   {
        CompanyNameList.push_back(cmp);
        return true;
   }


A: Here is your issue
lower_bound(CompanyNameList.begin(), CompanyIDList.end(), cmp, Company::compareByNA); 

You are mixing up your lists.
You probably meant to use
lower_bound(CompanyNameList.begin(), CompanyNameList.end(), cmp, Company::compareByNA); 

