[corlib] Decimal parsing with banker's rounding with non-zero digits …

…beyond the thousandths digit. Fixes #17536
mono · Jan 31, 2014 · a5fc91f · a5fc91f
1 parent d64b215
commit a5fc91f
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Showing 2 changed files with 17 additions and 13 deletions.
diff --git a/mcs/class/corlib/System/Decimal.cs b/mcs/class/corlib/System/Decimal.cs
@@ -4,14 +4,13 @@
 // Represents a floating-point decimal data type with up to 29 
 // significant digits, suitable for financial and commercial calculations.
 //
-// Author:
+// Authors:
 //   Martin Weindel (martin.weindel@t-online.de)
+//   Marek Safar (marek.safar@gmail.com)
 //
 // (C) 2001 Martin Weindel
-//
-
-//
 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
+// Copyright (C) 2014 Xamarin Inc (http://www.xamarin.com)
 //
 // Permission is hereby granted, free of charge, to any person obtaining
 // a copy of this software and associated documentation files (the
@@ -1081,22 +1080,25 @@ static bool PerformParse (string s, NumberStyles style, IFormatProvider provider
 			// then we trunc the string
 			if ((len > max) && (iDecPos < len)) {
 				int round = (s [max] - '0');
-				s = s.Substring (0, max);
 
 				bool addone = false;
 				if (round > 5) {
 					addone = true;
-				}
-				else if (round == 5) {
+				} else if (round == 5) {
 					if (isNegative) {
 						addone = true;
-					}
-					else {
-						// banker rounding applies :(
-						int previous = (s [max - 1] - '0');
-						addone = ((previous & 0x01) == 0x01);
+					} else {
+						// banker's rounding applies
+						if (len > max) {
+							addone = s [max + 1] > '0';
+						} else {
+							int previous = s [max - 1] - '0';
+							addone = ((previous & 0x01) == 0x01);
+						}
 					}
 				}
+
+				s = s.Substring (0, max);
 				if (addone) {
 					char[] array = s.ToCharArray ();
 					int p = max - 1;

diff --git a/mcs/class/corlib/Test/System/DecimalTest.cs b/mcs/class/corlib/Test/System/DecimalTest.cs
@@ -335,7 +335,9 @@ public void TestPercentPattern ()
 				new ParseTest("-000000000000001922816251426433759354395033.300000000000000", -1922816251426433759354395033.3m),
 				new ParseTest("-7922816251426433759354395033.150000000000", -7922816251426433759354395033.2m),
 				new ParseTest("-7922816251426433759354395033.2400000000000", -7922816251426433759354395033.2m),
-				new ParseTest("-7922816251426433759354395033.2600000000000", -7922816251426433759354395033.3m)
+				new ParseTest("-7922816251426433759354395033.2600000000000", -7922816251426433759354395033.3m),
+				new ParseTest("987654321098765432109876543.25999", 987654321098765432109876543.3m, NumberStyles.Float)
+
 		};
 
 		[Test]