how replace a record ?
This example delete a record and 
add a record with a new field value.
// createtable.php
<? 
$dbname = "players.dbf";  
$def = array
( 
array("record",  "N",8,0),  
array("account",  "C",10), 
array("password",  "C",5),
array("name",  "C",30)
); 
if (!dbase_create($dbname, $def)) 
{
print "<strong>Error! <BR> Try: chmod 707 tabledirectory</strong>";
} 
else  
{
print "<strong>The table ".$dbname." was created !</strong>";
} 
?>
// addrecord.php
// just a test, you can add more features to send the data by a html form and validate the account
<?
$db=dbase_open("players.dbf",); 
 $nextrecord = 1;
 for ($a=1; $a <= $nr; $a++) 
  {
     $rec = dbase_get_record($db, $a); 
     $nextrecord = $rec[0]+1;
  }
 $def = array ($nextrecord,'hsanchez', 'hugol', 'hugo sanchez');  
    dbase_add_record($db, $def);  
    dbase_close($db);  
?>
// modify.htm 
<FORM ACTION='modify.php' METHOD='post'>
<TABLE BORDER='9'>
<TR>
<TD>Account</TD><TD>Password</TD><TD>Name</TD>
</TR>
<TR>
<TD><INPUT TYPE='TEXT' SIZE='10' MAXLENGTH='10' NAME='f_account></TD><TD><INPUT TYPE='PASSWORD' SIZE='5' MAXLENGTH='5' NAME='f_password'></TD><TD><INPUT TYPE='TEXT' SIZE='30' MAXLENGTH='30' NAME='f_name'></TD>
</TR>
</TABLE>
<BR>
<INPUT TYPE='Submit' VALUE='Modify'><BR>
</FORM>
</CENTER>
</BODY>
</HTML>
// modify.php
<? 
$exist = 0;
$db=dbase_open("players.dbf",0); 
$nr = dbase_numrecords($db); 
if ($nr==0) 
  {
    print "There's no players !"; 
  }
else
  {
    for ($a=1; $a <= $nr; $a++) 
     {
     $rec = dbase_get_record($db, $a); 
     if ( !strcasecmp (trim($rec[1]), trim($f_account)) and !strcasecmp (trim($rec[2]), trim($f_password)))
        {
           $exist = 1;
           $nrm = $a;
           break;
        } 
     }
  }
dbase_close($db);  
if ($exist == 1) {
  if ($f_name and $f_account and $f_password) 
  {
    $db=dbase_open("players.dbf",2);  
    dbase_delete_record($db,$nrm);  
    dbase_pack($db); 
    dbase_close($db); 
    $db=dbase_open("players.dbf",2);  
    $def = array($nrm,trim($f_account),$f_password,trim($f_name));  
    dbase_add_record($db, $def);  
    print "The name was updated !"; 
  }
  else
  { 
    print "<strong>Error, enter alll data!</strong>";
  }
}
if ($exist == 0) 
 {
  print "<strong>Error, the data is not valid !</strong>";
 }
?>
That's all !
I know that there is a dbase-replace-record function but i could use it.