-Fixed JsonTextReader.ReadAsString incorrectly erroring when reading some numbers

Src/Newtonsoft.Json.Tests/JsonTextReaderTest.cs

@@ -61,6 +61,37 @@ namespace Newtonsoft.Json.Tests
     [TestFixture]
     public class JsonTextReaderTest : TestFixtureBase
     {
+        [Test]
+        public void FloatParseHandling_ReadAsString()
+        {
+            string json = "[9223372036854775807, 1.7976931348623157E+308, 792281625142643375935439503.35, 792281625142643375935555555555555555555555555555555555555555555555555439503.35]";
+
+            JsonTextReader reader = new JsonTextReader(new StringReader(json));
+            reader.FloatParseHandling = Json.FloatParseHandling.Decimal;
+
+            Assert.IsTrue(reader.Read());
+            Assert.AreEqual(JsonToken.StartArray, reader.TokenType);
+
+            Assert.AreEqual("9223372036854775807", reader.ReadAsString());
+            Assert.AreEqual(JsonToken.String, reader.TokenType);
+            Assert.AreEqual("9223372036854775807", reader.Value);
+
+            Assert.AreEqual("1.7976931348623157E+308", reader.ReadAsString());
+            Assert.AreEqual(JsonToken.String, reader.TokenType);
+            Assert.AreEqual("1.7976931348623157E+308", reader.Value);
+
+            Assert.AreEqual("792281625142643375935439503.35", reader.ReadAsString());
+            Assert.AreEqual(JsonToken.String, reader.TokenType);
+            Assert.AreEqual("792281625142643375935439503.35", reader.Value);
+
+            Assert.AreEqual("792281625142643375935555555555555555555555555555555555555555555555555439503.35", reader.ReadAsString());
+            Assert.AreEqual(JsonToken.String, reader.TokenType);
+            Assert.AreEqual("792281625142643375935555555555555555555555555555555555555555555555555439503.35", reader.Value);
+
+            Assert.IsTrue(reader.Read());
+            Assert.AreEqual(JsonToken.EndArray, reader.TokenType);
+        }
+
         [Test]
         public void LineInfoAndNewLines()
         {

Src/Newtonsoft.Json/JsonTextReader.cs

@@ -614,10 +614,8 @@ namespace Newtonsoft.Json
                                     _charPos++;
                                     throw CreateUnexpectedCharacterException(currentChar);
                                 }
-                                ParseNumber(ReadType.Read);
-                                string s = ((IFormattable)Value).ToString(null, CultureInfo.InvariantCulture);
-                                SetToken(JsonToken.String, s);
-                                return s;
+                                ParseNumber(ReadType.ReadAsString);
+                                return Value;
                             case 't':
                             case 'f':
                                 if (readType != ReadType.ReadAsString)
@@ -1807,7 +1805,42 @@ namespace Newtonsoft.Json
             bool singleDigit = (char.IsDigit(firstChar) && _stringReference.Length == 1);
             bool nonBase10 = (firstChar == '0' && _stringReference.Length > 1 && _stringReference.Chars[_stringReference.StartIndex + 1] != '.' && _stringReference.Chars[_stringReference.StartIndex + 1] != 'e' && _stringReference.Chars[_stringReference.StartIndex + 1] != 'E');
 
-            if (readType == ReadType.ReadAsInt32)
+            if (readType == ReadType.ReadAsString)
+            {
+                string number = _stringReference.ToString();
+
+                // validate that the string is a valid number
+                if (nonBase10)
+                {
+                    try
+                    {
+                        if (number.StartsWith("0x", StringComparison.OrdinalIgnoreCase))
+                        {
+                            Convert.ToInt64(number, 16);
+                        }
+                        else
+                        {
+                            Convert.ToInt64(number, 8);
+                        }
+                    }
+                    catch (Exception ex)
+                    {
+                        throw JsonReaderException.Create(this, "Input string '{0}' is not a valid number.".FormatWith(CultureInfo.InvariantCulture, number), ex);
+                    }
+                }
+                else
+                {
+                    double value;
+                    if (!double.TryParse(number, NumberStyles.Float, CultureInfo.InvariantCulture, out value))
+                    {
+                        throw JsonReaderException.Create(this, "Input string '{0}' is not a valid number.".FormatWith(CultureInfo.InvariantCulture, _stringReference.ToString()));
+                    }
+                }
+
+                numberType = JsonToken.String;
+                numberValue = number;
+            }
+            else if (readType == ReadType.ReadAsInt32)
             {
                 if (singleDigit)
                 {