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diff --git a/include/jsoncons/detail/write_number.hpp b/include/jsoncons/detail/write_number.hpp
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+++ b/include/jsoncons/detail/write_number.hpp
@@ -0,0 +1,567 @@
+// Copyright 2013 Daniel Parker
+// Distributed under the Boost license, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See https://github.com/danielaparker/jsoncons for latest version
+
+#ifndef JSONCONS_DETAIL_WRITE_NUMBER_HPP
+#define JSONCONS_DETAIL_WRITE_NUMBER_HPP
+
+#include <stdexcept>
+#include <string>
+#include <cmath>
+#include <locale>
+#include <limits> // std::numeric_limits
+#include <exception>
+#include <stdio.h> // snprintf
+#include <jsoncons/config/jsoncons_config.hpp>
+#include <jsoncons/json_options.hpp>
+#include <jsoncons/detail/grisu3.hpp>
+#include <jsoncons/detail/parse_number.hpp>
+#include <jsoncons/more_type_traits.hpp>
+
+namespace jsoncons { 
+namespace detail {
+
+    inline
+    char to_hex_character(uint8_t c)
+    {
+        return (char)((c < 10) ? ('0' + c) : ('A' - 10 + c));
+    }
+
+    // from_integer
+
+    template<class Integer,class Result>
+    typename std::enable_if<type_traits::is_integer<Integer>::value,std::size_t>::type
+    from_integer(Integer value, Result& result)
+    {
+        using char_type = typename Result::value_type;
+
+        char_type buf[255];
+        char_type *p = buf;
+        const char_type* last = buf+255;
+
+        bool is_negative = value < 0;
+
+        if (value < 0)
+        {
+            do
+            {
+                *p++ = static_cast<char_type>(48 - (value % 10));
+            }
+            while ((value /= 10) && (p < last));
+        }
+        else
+        {
+
+            do
+            {
+                *p++ = static_cast<char_type>(48 + value % 10);
+            }
+            while ((value /= 10) && (p < last));
+        }
+        JSONCONS_ASSERT(p != last);
+
+        std::size_t count = (p - buf);
+        if (is_negative)
+        {
+            result.push_back('-');
+            ++count;
+        }
+        while (--p >= buf)
+        {
+            result.push_back(*p);
+        }
+
+        return count;
+    }
+
+    // integer_to_string_hex
+
+    template<class Integer,class Result>
+    typename std::enable_if<type_traits::is_integer<Integer>::value,std::size_t>::type
+    integer_to_string_hex(Integer value, Result& result)
+    {
+        using char_type = typename Result::value_type;
+
+        char_type buf[255];
+        char_type *p = buf;
+        const char_type* last = buf+255;
+
+        bool is_negative = value < 0;
+
+        if (value < 0)
+        {
+            do
+            {
+                *p++ = to_hex_character(0-(value % 16));
+            }
+            while ((value /= 16) && (p < last));
+        }
+        else
+        {
+
+            do
+            {
+                *p++ = to_hex_character(value % 16);
+            }
+            while ((value /= 16) && (p < last));
+        }
+        JSONCONS_ASSERT(p != last);
+
+        std::size_t count = (p - buf);
+        if (is_negative)
+        {
+            result.push_back('-');
+            ++count;
+        }
+        while (--p >= buf)
+        {
+            result.push_back(*p);
+        }
+
+        return count;
+    }
+
+    // write_double
+
+    // fast exponent
+    template <class Result>
+    void fill_exponent(int K, Result& result)
+    {
+        if (K < 0)
+        {
+            result.push_back('-');
+            K = -K;
+        }
+        else
+        {
+            result.push_back('+'); // compatibility with sprintf
+        }
+
+        if (K < 10)
+        {
+            result.push_back('0'); // compatibility with sprintf
+            result.push_back((char)('0' + K));
+        }
+        else if (K < 100)
+        {
+            result.push_back((char)('0' + K / 10)); K %= 10;
+            result.push_back((char)('0' + K));
+        }
+        else if (K < 1000)
+        {
+            result.push_back((char)('0' + K / 100)); K %= 100;
+            result.push_back((char)('0' + K / 10)); K %= 10;
+            result.push_back((char)('0' + K));
+        }
+        else
+        {
+            jsoncons::detail::from_integer(K, result);
+        }
+    }
+
+    template <class Result>
+    void prettify_string(const char *buffer, std::size_t length, int k, int min_exp, int max_exp, Result& result)
+    {
+        int nb_digits = (int)length;
+        int offset;
+        /* v = buffer * 10^k
+           kk is such that 10^(kk-1) <= v < 10^kk
+           this way kk gives the position of the decimal point.
+        */
+        int kk = nb_digits + k;
+
+        if (nb_digits <= kk && kk <= max_exp)
+        {
+            /* the first digits are already in. Add some 0s and call it a day. */
+            /* the max_exp is a personal choice. Only 16 digits could possibly be relevant.
+             * Basically we want to print 12340000000 rather than 1234.0e7 or 1.234e10 */
+            for (int i = 0; i < nb_digits; ++i)
+            {
+                result.push_back(buffer[i]);
+            }
+            for (int i = nb_digits; i < kk; ++i)
+            {
+                result.push_back('0');
+            }
+            result.push_back('.');
+            result.push_back('0');
+        } 
+        else if (0 < kk && kk <= max_exp)
+        {
+            /* comma number. Just insert a '.' at the correct location. */
+            for (int i = 0; i < kk; ++i)
+            {
+                result.push_back(buffer[i]);
+            }
+            result.push_back('.');
+            for (int i = kk; i < nb_digits; ++i)
+            {
+                result.push_back(buffer[i]);
+            }
+        } 
+        else if (min_exp < kk && kk <= 0)
+        {
+            offset = 2 - kk;
+
+            result.push_back('0');
+            result.push_back('.');
+            for (int i = 2; i < offset; ++i) 
+                result.push_back('0');
+            for (int i = 0; i < nb_digits; ++i)
+            {
+                result.push_back(buffer[i]);
+            }
+        } 
+        else if (nb_digits == 1)
+        {
+            result.push_back(buffer[0]);
+            result.push_back('e');
+            fill_exponent(kk - 1, result);
+        } 
+        else
+        {
+            result.push_back(buffer[0]);
+            result.push_back('.');
+            for (int i = 1; i < nb_digits; ++i)
+            {
+                result.push_back(buffer[i]);
+            }
+            result.push_back('e');
+            fill_exponent(kk - 1, result);
+        }
+    }
+
+    template<class Result>
+    void dump_buffer(const char *buffer, std::size_t length, char decimal_point, Result& result)
+    {
+        const char *sbeg = buffer;
+        const char *send = sbeg + length;
+
+        if (sbeg != send)
+        {
+            bool needs_dot = true;
+            for (const char* q = sbeg; q < send; ++q)
+            {
+                switch (*q)
+                {
+                case '-':
+                case '0':
+                case '1':
+                case '2':
+                case '3':
+                case '4':
+                case '5':
+                case '6':
+                case '7':
+                case '8':
+                case '9':
+                case '+':
+                    result.push_back(*q);
+                    break;
+                case 'e':
+                case 'E':
+                    result.push_back('e');
+                    needs_dot = false;
+                    break;
+                default:
+                    if (*q == decimal_point)
+                    {
+                        needs_dot = false;
+                        result.push_back('.');
+                    }
+                    break;
+                }
+            }
+            if (needs_dot)
+            {
+                result.push_back('.');
+                result.push_back('0');
+                needs_dot = true;
+            }
+        }
+    }
+
+    template<class Result>
+    bool dtoa_scientific(double val, char decimal_point, Result& result)
+    {
+        if (val == 0)
+        {
+            result.push_back('0');
+            result.push_back('.');
+            result.push_back('0');
+            return true;
+        }
+
+        jsoncons::detail::chars_to to_double_;
+
+        char buffer[100];
+        int precision = std::numeric_limits<double>::digits10;
+        int length = snprintf(buffer, sizeof(buffer), "%1.*e", precision, val);
+        if (length < 0)
+        {
+            return false;
+        }
+        if (to_double_(buffer, sizeof(buffer)) != val)
+        {
+            const int precision2 = std::numeric_limits<double>::max_digits10;
+            length = snprintf(buffer, sizeof(buffer), "%1.*e", precision2, val);
+            if (length < 0)
+            {
+                return false;
+            }
+        }
+        dump_buffer(buffer, static_cast<std::size_t>(length), decimal_point, result);
+        return true;
+    }
+
+    template<class Result>
+    bool dtoa_general(double val, char decimal_point, Result& result, std::false_type)
+    {
+        if (val == 0)
+        {
+            result.push_back('0');
+            result.push_back('.');
+            result.push_back('0');
+            return true;
+        }
+
+        jsoncons::detail::chars_to to_double_;
+
+        char buffer[100];
+        int precision = std::numeric_limits<double>::digits10;
+        int length = snprintf(buffer, sizeof(buffer), "%1.*g", precision, val);
+        if (length < 0)
+        {
+            return false;
+        }
+        if (to_double_(buffer, sizeof(buffer)) != val)
+        {
+            const int precision2 = std::numeric_limits<double>::max_digits10;
+            length = snprintf(buffer, sizeof(buffer), "%1.*g", precision2, val);
+            if (length < 0)
+            {
+                return false;
+            }
+        }
+        dump_buffer(buffer, length, decimal_point, result);
+        return true;
+    }
+
+    template<class Result>
+    bool dtoa_general(double v, char decimal_point, Result& result, std::true_type)
+    {
+        if (v == 0)
+        {
+            result.push_back('0');
+            result.push_back('.');
+            result.push_back('0');
+            return true;
+        }
+
+        int length = 0;
+        int k;
+
+        char buffer[100];
+
+        double u = std::signbit(v) ? -v : v;
+        if (jsoncons::detail::grisu3(u, buffer, &length, &k))
+        {
+            if (std::signbit(v))
+            {
+                result.push_back('-');
+            }
+            // min exp: -4 is consistent with sprintf
+            // max exp: std::numeric_limits<double>::max_digits10
+            jsoncons::detail::prettify_string(buffer, length, k, -4, std::numeric_limits<double>::max_digits10, result);
+            return true;
+        }
+        else
+        {
+            return dtoa_general(v, decimal_point, result, std::false_type());
+        }
+    }
+
+    template<class Result>
+    bool dtoa_fixed(double val, char decimal_point, Result& result, std::false_type)
+    {
+        if (val == 0)
+        {
+            result.push_back('0');
+            result.push_back('.');
+            result.push_back('0');
+            return true;
+        }
+
+        jsoncons::detail::chars_to to_double_;
+
+        char buffer[100];
+        int precision = std::numeric_limits<double>::digits10;
+        int length = snprintf(buffer, sizeof(buffer), "%1.*f", precision, val);
+        if (length < 0)
+        {
+            return false;
+        }
+        if (to_double_(buffer, sizeof(buffer)) != val)
+        {
+            const int precision2 = std::numeric_limits<double>::max_digits10;
+            length = snprintf(buffer, sizeof(buffer), "%1.*f", precision2, val);
+            if (length < 0)
+            {
+                return false;
+            }
+        }
+        dump_buffer(buffer, length, decimal_point, result);
+        return true;
+    }
+
+    template<class Result>
+    bool dtoa_fixed(double v, char decimal_point, Result& result, std::true_type)
+    {
+        if (v == 0)
+        {
+            result.push_back('0');
+            result.push_back('.');
+            result.push_back('0');
+            return true;
+        }
+
+        int length = 0;
+        int k;
+
+        char buffer[100];
+
+        double u = std::signbit(v) ? -v : v;
+        if (jsoncons::detail::grisu3(u, buffer, &length, &k))
+        {
+            if (std::signbit(v))
+            {
+                result.push_back('-');
+            }
+            jsoncons::detail::prettify_string(buffer, length, k, std::numeric_limits<int>::lowest(), (std::numeric_limits<int>::max)(), result);
+            return true;
+        }
+        else
+        {
+            return dtoa_fixed(v, decimal_point, result, std::false_type());
+        }
+    }
+
+    template<class Result>
+    bool dtoa_fixed(double v, char decimal_point, Result& result)
+    {
+        return dtoa_fixed(v, decimal_point, result, std::integral_constant<bool, std::numeric_limits<double>::is_iec559>());
+    }
+
+    template<class Result>
+    bool dtoa_general(double v, char decimal_point, Result& result)
+    {
+        return dtoa_general(v, decimal_point, result, std::integral_constant<bool, std::numeric_limits<double>::is_iec559>());
+    }
+
+    class write_double
+    {
+    private:
+        chars_to to_double_;
+        float_chars_format float_format_;
+        int precision_;
+        char decimal_point_;
+    public:
+        write_double(float_chars_format float_format, int precision)
+           : float_format_(float_format), precision_(precision), decimal_point_('.')
+        {
+    #if !defined(JSONCONS_NO_LOCALECONV)
+            struct lconv *lc = localeconv();
+            if (lc != nullptr && lc->decimal_point[0] != 0)
+            {
+                decimal_point_ = lc->decimal_point[0];
+            }
+    #endif
+        }
+        write_double(const write_double&) = default;
+
+        write_double& operator=(const write_double&) = default;
+
+        template<class Result>
+        std::size_t operator()(double val, Result& result)
+        {
+            std::size_t count = 0;
+
+            char number_buffer[200];
+            int length = 0;
+
+            switch (float_format_)
+            {
+            case float_chars_format::fixed:
+                {
+                    if (precision_ > 0)
+                    {
+                        length = snprintf(number_buffer, sizeof(number_buffer), "%1.*f", precision_, val);
+                        if (length < 0)
+                        {
+                            JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                        }
+                        dump_buffer(number_buffer, length, decimal_point_, result);
+                    }
+                    else
+                    {
+                        if (!dtoa_fixed(val, decimal_point_, result))
+                        {
+                            JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                        }
+                    }
+                }
+                break;
+            case float_chars_format::scientific:
+                {
+                    if (precision_ > 0)
+                    {
+                        length = snprintf(number_buffer, sizeof(number_buffer), "%1.*e", precision_, val);
+                        if (length < 0)
+                        {
+                            JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                        }
+                        dump_buffer(number_buffer, length, decimal_point_, result);
+                    }
+                    else
+                    {
+                        if (!dtoa_scientific(val, decimal_point_, result))
+                        {
+                            JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                        }
+                    }
+                }
+                break;
+            case float_chars_format::general:
+                {
+                    if (precision_ > 0)
+                    {
+                        length = snprintf(number_buffer, sizeof(number_buffer), "%1.*g", precision_, val);
+                        if (length < 0)
+                        {
+                            JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                        }
+                        dump_buffer(number_buffer, length, decimal_point_, result);
+                    }
+                    else
+                    {
+                        if (!dtoa_general(val, decimal_point_, result))
+                        {
+                            JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                        }
+                    }             
+                    break;
+                }
+                default:
+                    JSONCONS_THROW(json_runtime_error<std::invalid_argument>("write_double failed."));
+                    break;
+            }
+            return count;
+        }
+    };
+
+} // namespace detail
+} // namespace jsoncons
+
+#endif