Re: Beware of round() function

Kirk.Johnson@zootweb.com wrote:

On Mon, 24 Mar 2008 13:10:17 -0600, Kirk.Johnson@zootweb.com wrote:

Beware: round() apparently has changed its behavior from PHP 4. For certain special numbers that seem to be multiples of 100,000, the

return

value is in exponential format, rather than the usual decimal format.

Some

of these special values are 1200000, 1400000, 2300000, which are

returned

as 1.2E+6, 1.4E+6, etc. You can generate your own list of these

special

numbers using this code: <?php for( $tmp = 0, $i = 0; $i < 100; $i++ ) {

    $tmp += 100000;
    echo round($tmp),"\n";

} ?>

I now have a list of 3 ways this change in behavior can bite you and result in a failed transaction. In the examples below, assume that the value passed to round() is '1200000', so that the value returned from round() is '1.2E+6'. 1. When interpolating the value into xml, resulting in an xsd validation error: <? $xml = '<AnnualIncome>' . round($income) . '</AnnualIncome>'; ?> 2. When validating user input, resulting in a false positive: <? if(!ereg("^[0-9]{1,10}$", round($_POST['income']))) { $errors .= "<li>Income should be whole dollars only (10 digits max).</li>"; } ?>

For the above test, is there any reason you couldn't use is_numeric() Looks like it would work in this case. <?php if ( ! is_numeric($_POST['income']) ) {

    $errors .= "<li>Income should be whole dollars only ".
               "(10 digits max).</li>";

} ?>

3. When interpolating a value into a stored procedure call, resulting in a type mismatch between the value passed in and the database column data type (which is likely decimal for a monetary value): <? $sql = "exec update_loan_financials

           @application_id='$appID',
           @total_debt=" . round($totalDebt);

?> BTW, a previous poster pointed out that this is a change in behavior of the float type, in general, not of the round() function, in particular. If you care. I don't. I just know I have broken code to fix and customers to apologize to. Kirk