[perl #23788] int of a fraction errors

From: "Boyd, Brooks D" (via RT) <perlbug-followup@perl.org>
Message-ID: <rt-23788-64511.8.7546744242259@rt.perl.org>

Add a separate faq entry for int().  (Yes, a bit redundant
with the existing "why are my numbers broken" entry.)

p4raw-id: //depot/perl@21204

diff --git a/pod/perlfaq4.pod b/pod/perlfaq4.pod
index af08e47..e2054e4 100644 (file)
--- a/pod/perlfaq4.pod
+++ b/pod/perlfaq4.pod
@@ -28,6 +28,24 @@ L<"Floating Point Arithmetic"|perlop> for more details.
 
        my $number = sprintf "%.2f", 10/3;
 
+=head2 Why is int() broken?
+
+Your int() is most probably working just fine.  It's the numbers that
+aren't quite what you think.
+
+First, see the above item "Why am I getting long decimals
+(eg, 19.9499999999999) instead of the numbers I should be getting
+(eg, 19.95)?".
+
+For example, this
+
+    print int(0.6/0.2-2), "\n";
+
+will in most computers print 0, not 1, because even such simple
+numbers as 0.6 and 0.2 cannot be presented exactly by floating-point
+numbers.  What you think in the above as 'three' is really more like
+2.9999999999999995559.
+
 =head2 Why isn't my octal data interpreted correctly?
 
 Perl only understands octal and hex numbers as such when they occur as