hexdump of arbitrary data

hexdump.cpp

#include <string>
#include <string_view>
#include <sstream>
#include <iomanip>

std::string hexdump(const char* buf, std::size_t len)
{
    constexpr std::size_t cols = 32;

    std::stringstream ss;
    ss << "[loc: " << (const void*)buf << "; bytes: " << len
      << "; hash: " << std::hash<std::string_view>()(std::string_view((const char*)buf, len)) << "]\n";
    ss << std::hex;

    for (size_t i = 0; i < len; i += cols)
    {
        size_t j = i;
        for (; j < len && j - i < cols; ++j)
            ss << std::setw(2) << std::setfill('0') << +(unsigned char)buf[j] << ' ';
        for (; j - i < cols; ++j)
            ss << "   ";

        ss << "| ";

        j = i;
        for (; j < len && j - i < cols; ++j)
        {
            if (buf[j] >= 32 && buf[j] < 128)
                ss << buf[j];
            else
                ss << ' ';
        }
        ss << '\n';
    }

    return ss.str();
}

(live demo)