clarify behavior of vec() when arguments are off the end of the

string (from M J T Guy)

p4raw-id: //depot/perl@5014

1 files changed, 7 insertions, 3 deletions

diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod
index c9efcd1231..88cbb0a6e5 100644
--- a/pod/perlfunc.pod
+++ b/pod/perlfunc.pod
@@ -5273,9 +5273,13 @@ to give the expression the correct precedence as in
 
     vec($image, $max_x * $x + $y, 8) = 3;
 
-Vectors created with C<vec> can also be manipulated with the logical
-operators C<|>, C<&>, and C<^>, which will assume a bit vector
-operation is desired when both operands are strings.
+If the selected element is off the end of the string, the value 0 is
+returned.  If an element off the end of the string is written to,
+Perl will first extend the string with sufficiently many zero bytes.
+
+Strings created with C<vec> can also be manipulated with the logical
+operators C<|>, C<&>, C<^>, and C<~>.  These operators will assume a bit
+vector operation is desired when both operands are strings.
 See L<perlop/"Bitwise String Operators">.
 
 The following code will build up an ASCII string saying C<'PerlPerlPerl'>.