PHP round different results

Question

Hi i got some problem with rounding. For ex.:

$x = 100;
$y = 4.2030;

$result = round($x / $y, 2);

$result will be 23.79

but now

  $result2 = round(23.79 * 4.2030, 2);

$result2 will be 99.99 , so it's incorrect. should be 100 ($result2 equal $X)

how to slove it ?

Obviously, you loose precision when rounding a number. round($x / y) != $x / $y — Qwerty, Aug 19 '13 at 20:00
Why should this be 100... 23.79*4.2030 = 99.98937 rounding to 2 digits after the decimal place should and does give you 99.99 — Orangepill, Aug 19 '13 at 20:01
`23.79 * 4.2030 = 99.989370` if you're going to need an *exact* value for a further calculation the you should be storing the *un*-rounded value and only round it for display. — Sammitch, Aug 19 '13 at 20:01
@jasneinfo, what means "rounding"? find out that, and you'll have your answer. — chris-l, Aug 19 '13 at 20:02
yeap, but need $result2 equal 100 . another way looking for a solution to maximum round near 100 but not higher — jasne, Aug 19 '13 at 20:04

Matthew R. · Answer 1 · 2013-08-19T20:14:10.087

1

Your round precision is two decimal places. If you are trying to get whole numbers you need to omit the precision argument:

$result2 = round(23.79 * 4.2030);

NOTE: the lower the precision argument, the more inaccurate your result will be from the actual results.

You can also use ceil() and floor() if you are looking to round in a specific direction (ceil() will round up, floor() will round down).

edited Aug 19 '13 at 20:14

answered Aug 19 '13 at 20:09

Matthew R.

1 Answers1