From: glowack2 at msu dot edu
Operating system: Linux
PHP version: 5.0.3
PHP Bug Type: *General Issues
Bug description: printf: %d not equal %s for some numbers
Description:
------------
printf (and sprintf) output incorrect values for certain inputs when using
the %d placeholder. For example, printf("%d",10.20*100) outputs "1019",
which is clearly not the correct and expected value of "1020". Most of
the time, the printed value is correct, but various numbers are off by
one. The off-by-one error is tied to specific numbers, and it is
repeatable. The off-by-one error also occurs when decimals are multiplied
by other powers of 10 (10, 100, 1000), though the numbers that produce
errors are not consistent between the different powers
This originally occured on a Solaris 5.6 machine running PHP 4.x, and has
been reproduced on a Linux machine running PHP 5.0.3.
The sample code included generates a table that verifies the output of %d
against %s (%s works correctly), green cells for matching output and red
cells with more details when the resulting text doesn't match.
Reproduce code:
---------------
print "<table>";
for($x=0;$x<1000;$x++) {
print "<tr>";
for($y=0.1;$y<1;$y=$y+0.1) {
// For more errors, replace *100 with *10 or *1000
// in the following two lines:
$string = sprintf("%s",($x+$y)*100);
$decimal = sprintf("%d",($x+$y)*100);
if(strcmp($string,$decimal)==0) {
print "<td bgcolor='#ddffdd'>$string</td>";
} else {
print "<td bgcolor='#ffdddd'>$string != $decimal</td>";
}
}
print "</tr>";
}
Expected result:
----------------
Every cell *should* be green, because sprintf should always convert
numbers accurately.
Actual result:
--------------
%d and %s output different results for certain decimal numbers. Only some
values come out incorrectly, and most are fine.
--
Edit bug report at http://bugs.php.net/?id=32488&edit=1
--
Try a CVS snapshot (php4): http://bugs.php.net/fix.php?id=32488&r=trysnapshot4
Try a CVS snapshot (php5.0):
http://bugs.php.net/fix.php?id=32488&r=trysnapshot50
Try a CVS snapshot (php5.1):
http://bugs.php.net/fix.php?id=32488&r=trysnapshot51
Fixed in CVS: http://bugs.php.net/fix.php?id=32488&r=fixedcvs
Fixed in release: http://bugs.php.net/fix.php?id=32488&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=32488&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=32488&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=32488&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=32488&r=support
Expected behavior: http://bugs.php.net/fix.php?id=32488&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=32488&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=32488&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=32488&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=32488&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=32488&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=32488&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=32488&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=32488&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=32488&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=32488&r=mysqlcfg
