Merge lp:~mcbits/pantheon-calculator/fix-1415049 into lp:~elementary-apps/pantheon-calculator/trunk

[James McManus]

Fix calculator bug #1415049 where some calculations produce negative 0

Fix calculator bug #1415049 by rounding results to the given precision and ensuring any 0.0 results are positive before formatting for display.

[MarkoD (markodolar)]

Looks like with this fix calculator now properly outputs number of decimal places :)

But this also introduces small bug - if d_places is 0 and equation result is "0", calculator will crash in cut() trying to slice radix character off an empty string.

review: Needs Fixing

Unmerged revisions

296. By James McManus <email address hidden> on 2016-12-05

Fix calculator bug #1415049 where some calculations produce negative 0

=== modified file 'src/Core/Evaluation.vala'
--- src/Core/Evaluation.vala	2015-04-03 12:04:47 +0000
+++ src/Core/Evaluation.vala	2016-12-06 00:03:47 +0000
@@ -276,7 +276,13 @@
         }
 
         private string cut (double d, int d_places) {
-            var s = ("%.5f".printf (d));
+            // First round to the given decimal places and ensure
+            // anything that rounds to -0.0 becomes positive 0.0.
+            double scale = pow10(d_places);
+            double rounded_value = round(d * scale) / scale + 0.0;
+
+            // Convert to string and strip trailing 0s.
+            var s = ("%.*f".printf (d_places, rounded_value));
             while (s.last_index_of ("0") == s.length - 1)
                 s = s.slice (0, s.length - 1);
             if (s.last_index_of (Posix.nl_langinfo (Posix.NLItem.RADIXCHAR)) == s.length - 1)