I wanted to replace any umlauts with strings (not chars in octal...) like "\200". I used ereg_replace for this and it worked until PHP 4.2.0 was released. Than php just crashed. I now know there are better solutions to accomplish this, e.g. str_replace... But on the other hand, php shouldn't crash on user input...

Here is the code:

<?php
  $x = "a?b?c";
  $x = ereg_replace ( "?" , "\\200" , $x );
  print "$x\n";
  $x = ereg_replace ( "?" , "\\234" , $x );
  print "$x\n";
?>

The problem is, \\2 is taken as an index into an array, which has only one element. The fix is easy, just check the digit if it is a valid index:

--- reg.c       Sun May  5 10:39:57 2002
+++ reg.c.new   Fri Jun 14 16:13:38 2002
@@ -341,6 +341,7 @@
                        while (*walk)
                                if ('\\' == *walk
                                        && '0' <= walk[1] && '9' >= walk[1]
+                                       && walk[1] - '0' <= re.re_nsub
                                        && subs[walk[1] - '0'].rm_so > -1
                                        && subs[walk[1] - '0'].rm_eo > -1) {
                                        new_l += subs[walk[1] - '0'].rm_eo
@@ -368,6 +369,7 @@
                        while (*walk)
                                if ('\\' == *walk
                                        && '0' <= walk[1] && '9' >= walk[1]
+                                       && walk[1] - '0' <= re.re_nsub
                                        && subs[walk[1] - '0'].rm_so > -1
                                        && subs[walk[1] - '0'].rm_eo > -1
                                        /* this next case shouldn't happen. it does. */