clarify behaviour of $a++

p4raw-id: //depot/perl@19014

diff --git a/pod/perlop.pod b/pod/perlop.pod
index ad46301..cd36ec1 100644 (file)
--- a/pod/perlop.pod
+++ b/pod/perlop.pod
@@ -127,6 +127,10 @@ character within its range, with carry:
     print ++($foo = 'Az');     # prints 'Ba'
     print ++($foo = 'zz');     # prints 'aaa'
 
+C<undef> is always treated as numeric, and in particular is changed
+to C<0> before incrementing (so that a post-increment of an undef value
+will return C<0> rather than C<undef>).
+
 The auto-decrement operator is not magical.
 
 =head2 Exponentiation