i am sorting an array of strings using uasort($a,'isoCompare').

the user function isoCompare, in its recursive variant, crashes randomly.

first, the support function charPower which remaps diacritical chars... this one is ok.

function charPower ($ch,$charPowerCaseSensitive=FALSE,$charPowerReverseOrder=FALSE) {
        $power = 0;
        $char = ($charPowerCaseSensitive ? $ch : strtoupper($ch));
        switch (ord($char)) {
                case 232: $power = 10*ord(($charPowerCaseSensitive ? "c" : "C")
                case 200: $power = 10*ord("C")+3; break;
                case 190: $power = 10*ord(($charPowerCaseSensitive ? "z" : "Z")
                case 174: $power = 10*ord("Z")+5; break;
                case 185: $power = 10*ord(($charPowerCaseSensitive ? "s" : "S")
                case 169: $power = 10*ord("S")+5; break;
                case 230: $power = 10*ord(($charPowerCaseSensitive ? "c" : "C")
                case 198: $power = 10*ord("C")+6; break;
                case 240: $power = 10*ord(($charPowerCaseSensitive ? "d" : "D")
                case 208: $power = 10*ord("D")+5; break;
                default: $power = 10*ord($char);
        }
        return ($charPowerReverseOrder ? ((-1)*$power) : $power);
} ;

now the recursive isoCompare...

function isoCompare ($s1,$s2) {
        $len1 = strlen($s1);
        $len2 = strlen($s2);
        if ($len1==0 || $len2==0) {
          $ret = $len1 - $len2;
          if (!$ret) return 0;
          else return $ret > 0 ? +1 : -1;
        } ;
        $c1 = charPower($s1);
        $c2 = charPower($s2);
        $power1 = charPower($c1) ;
        $power2 = charPower($c2) ;
        if ($power1==$power2) {
          $ret = isoCompare(substr($s1,1), substr($s2,1));
          return $ret;
        } else {
          $ret = $power1-$power2;
          return $ret > 0 ? +1 : -1;
        }
}

the iterative version works fine:

function isoCompare ($s1, $s2) {
  global $isadmin;
    $i = 0; $ret = 0;
    while (!$ret) {
      $len1 = strlen($s1);
      $len2 = strlen($s2);
      if ($len1 == 0 && $len2 == 0) $ret = 0;
      elseif ($len1 == 0) $ret = 1;
      elseif ($len2 == 0) $ret = -1 ;
      else {
        $power1 = charPower(substr($s1,0,1)) ;
        $power2 = charPower(substr($s2,0,1)) ;
        if ($power1 > $power2) $ret = 1;
        elseif ($power2 > $power1) $ret = -1;
        else {
          $s1 = substr($s1,1);
          $s2 = substr($s2,1);
        } ;
      } ;
    } ; // while
    return $ret;
} ;

my setup:

./configure \
--with-config-file-path=/usr/local/lib \
--with-zlib \
--with-mysql=/usr/local/mysql \
--with-exec-dir=/usr/local/safe_mode --enable-track-vars=yes \
--enable-magic-quotes=yes --disable-debug \
--with-pdflib \
--with-xml \
--with-sablot=/usr/local/lib \
--with-expat=/usr/local/lib \
--enable-sysvsem \
--enable-sysvshm \
--with-gd \
--with-iconv \
--with-curl=/usr/local/curl \
--with-apxs=/usr/local/apache/bin/apxs