source: binary-improvements/7dtd-server-fixes/src/JSON/JSONNumber.cs@ 331

using System;
using System.Text;

namespace AllocsFixes.JSON {
        public class JSONNumber : JSONValue {
                private readonly double value;

                public JSONNumber (double value) {
                        this.value = value;
                }

                public double GetDouble () {
                        return value;
                }

                public int GetInt () {
                        return (int) Math.Round (value);
                }

                public override void ToString (StringBuilder stringBuilder, bool prettyPrint = false, int currentLevel = 0) {
                        stringBuilder.Append (value.ToCultureInvariantString ());
                }

                public static JSONNumber Parse (string json, ref int offset) {
                        //Log.Out ("ParseNumber enter (" + offset + ")");
                        StringBuilder sbNum = new StringBuilder ();
                        StringBuilder sbExp = null;
                        bool hasDec = false;
                        bool hasExp = false;
                        while (offset < json.Length) {
                                if (json [offset] >= '0' && json [offset] <= '9') {
                                        if (hasExp) {
                                                sbExp.Append (json [offset]);
                                        } else {
                                                sbNum.Append (json [offset]);
                                        }
                                } else if (json [offset] == '.') {
                                        if (hasExp) {
                                                throw new MalformedJSONException ("Decimal separator in exponent");
                                        }

                                        if (hasDec) {
                                                throw new MalformedJSONException ("Multiple decimal separators in number found");
                                        }

                                        if (sbNum.Length == 0) {
                                                throw new MalformedJSONException ("No leading digits before decimal separator found");
                                        }

                                        sbNum.Append ('.');
                                        hasDec = true;
                                } else if (json [offset] == '-') {
                                        if (hasExp) {
                                                if (sbExp.Length > 0) {
                                                        throw new MalformedJSONException ("Negative sign in exponent after digits");
                                                }

                                                sbExp.Append (json [offset]);
                                        } else {
                                                if (sbNum.Length > 0) {
                                                        throw new MalformedJSONException ("Negative sign in mantissa after digits");
                                                }

                                                sbNum.Append (json [offset]);
                                        }
                                } else if (json [offset] == 'e' || json [offset] == 'E') {
                                        if (hasExp) {
                                                throw new MalformedJSONException ("Multiple exponential markers in number found");
                                        }

                                        if (sbNum.Length == 0) {
                                                throw new MalformedJSONException ("No leading digits before exponential marker found");
                                        }

                                        sbExp = new StringBuilder ();
                                        hasExp = true;
                                } else if (json [offset] == '+') {
                                        if (hasExp) {
                                                if (sbExp.Length > 0) {
                                                        throw new MalformedJSONException ("Positive sign in exponent after digits");
                                                }

                                                sbExp.Append (json [offset]);
                                        } else {
                                                throw new MalformedJSONException ("Positive sign in mantissa found");
                                        }
                                } else {
                                        double number;
                                        if (!StringParsers.TryParseDouble (sbNum.ToString (), out number)) {
                                                throw new MalformedJSONException ("Mantissa is not a valid decimal (\"" + sbNum + "\")");
                                        }

                                        if (hasExp) {
                                                int exp;
                                                if (!int.TryParse (sbExp.ToString (), out exp)) {
                                                        throw new MalformedJSONException ("Exponent is not a valid integer (\"" + sbExp + "\")");
                                                }

                                                number = number * Math.Pow (10, exp);
                                        }

                                        //Log.Out ("JSON:Parsed Number: " + number.ToString ());
                                        return new JSONNumber (number);
                                }

                                offset++;
                        }

                        throw new MalformedJSONException ("End of JSON reached before parsing number finished");
                }
        }
}