Fix issue when serializing float/double that are either NaN or Infinity.

SharpYaml/Serialization/Serializers/PrimitiveSerializer.cs

@@ -165,17 +165,24 @@ namespace SharpYaml.Serialization.Serializers
 	    /// Appends decimal point to arg if it does not exist
 	    /// </summary>
 	    /// <param name="text"></param>
+        /// <param name="hasNaN">True if the floating point type supports NaN or Infinity.</param>
 	    /// <returns></returns>
-        private string AppendDecimalPoint(string text )
+	    private static string AppendDecimalPoint(string text, bool hasNaN)
         {
-            for (int i = 0; i < text.Length; i++)
+            for (var i = 0; i < text.Length; i++)
             {
                 var c = text[i];
+                // Do not append a decimal point if floating point type value
+                // - is in exponential form, or
+                // - already has a decimal point
                 if (c == 'e' || c == 'E' || c == '.')
                 {
                     return text;
                 }
             }
+            // Special cases for floating point type supporting NaN and Infinity
+            if (hasNaN && (string.Equals(text, "NaN") || text.Contains("Infinity")))
+                return text;
 
             return text + ".0";
         }
@@ -237,13 +244,13 @@ namespace SharpYaml.Serialization.Serializers
 					case TypeCode.Single:
                         //Append decimal point to floating point type values 
                         //because type changes in round trip conversion if ( value * 10.0 ) % 10.0 == 0
-                        text = AppendDecimalPoint(((float)value).ToString("R", CultureInfo.InvariantCulture));
+                        text = AppendDecimalPoint(((float)value).ToString("R", CultureInfo.InvariantCulture), true);
 						break;
 					case TypeCode.Double:
-                        text = AppendDecimalPoint(((double)value).ToString("R", CultureInfo.InvariantCulture));
+                        text = AppendDecimalPoint(((double)value).ToString("R", CultureInfo.InvariantCulture), true);
 						break;
 					case TypeCode.Decimal:
-                        text = AppendDecimalPoint(((decimal)value).ToString("G", CultureInfo.InvariantCulture));
+                        text = AppendDecimalPoint(((decimal)value).ToString("G", CultureInfo.InvariantCulture), false);
 						break;
 					case TypeCode.DateTime:
 						text = ((DateTime) value).ToString("o", CultureInfo.InvariantCulture);