Conversion from signed string to unsigned

[mwoods]

Any ideas for a more efficient and safer conversion from signed string to unsigned?

std::basic_string<unsigned char> string_to_unsigned(const std::string& s)
{
    int size = s.size();
    const char* p;
    std::basic_string<unsigned char> output;
    output.reserve(size);

    if (size)
    {
        p = &s[0];
        for (int i = 0; i < size; ++i)
        {
            output.push_back(*((const unsigned char*)p));

            ++p;
        }
    }

    return output;
}

[laserlight]

I do not know if this is faster, but it certainly is simpler:

inline std::basic_string<unsigned char> string_to_unsigned(const std::string& s)
{
    return std::basic_string<unsigned char>(s.begin(), s.end());
}

[mwoods]

Originally Posted by laserlight

I do not know if this is faster, but it certainly is simpler:

inline std::basic_string<unsigned char> string_to_unsigned(const std::string& s)
{
    return std::basic_string<unsigned char>(s.begin(), s.end());
}

That seems to be more sensible. Although, I didn't contemplate anything similar at first because I wasn't sure whether implicit conversions between class types were allowed in C++.

[Lindley]

The only conversion required by laserlight's code is that a char be implicitly convertible to an unsigned char. Which it is.