[.NET Timexlib] Fix timex-to-string conversion of English ordinals 11-13 (#2896)

Author: shana

.NET/Microsoft.Recognizers.Text.DataTypes.DataDrivenTests/TestTimex.cs

@@ -127,6 +127,17 @@ public void DataTypes_Timex_FromTime()
             Assert.AreEqual("T23:59:30", TimexProperty.FromTime(new Time(23, 59, 30)).TimexValue);
         }
 
+        [TestMethod]
+        public void DataTypes_Timex_FromDateTime_ToString()
+        {
+            var timex = new TimexProperty("2022-03-11");
+            Assert.AreEqual("11th March 2022", timex.ToString());
+            timex = new TimexProperty("2022-03-12");
+            Assert.AreEqual("12th March 2022", timex.ToString());
+            timex = new TimexProperty("2022-03-13");
+            Assert.AreEqual("13th March 2022", timex.ToString());
+        }
+
         private static void Roundtrip(string timex)
         {
             Assert.AreEqual(timex, new TimexProperty(timex).TimexValue);

.NET/Microsoft.Recognizers.Text.DataTypes.TimexExpression/English/TimexConvertEnglish.cs

@@ -97,7 +97,10 @@ public static string ConvertDate(TimexProperty timex)
             }
 
             var date = timex.DayOfMonth.Value.ToString(CultureInfo.InvariantCulture);
-            var abbreviation = TimexConstantsEnglish.DateAbbreviation[int.Parse(date[date.Length - 1].ToString(CultureInfo.InvariantCulture), CultureInfo.InvariantCulture)];
+            var dayOfMonth = int.Parse(date, CultureInfo.InvariantCulture);
+
+            // Ordinals 11 to 13 are special in english as they end in th
+            var abbreviation = TimexConstantsEnglish.DateAbbreviation[(dayOfMonth is > 9 and < 14 ? 9 : dayOfMonth) % 10];
 
             if (timex.Month != null)
             {