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Editorial Team
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Asked: 2026-06-18T05:07:12+00:00

Possible Duplicate: Practices to limit floating point accuracy problems When I am adding a

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Possible Duplicate:
Practices to limit floating point accuracy problems

When I am adding a list of new totalSubs to a running total, PHP returns a weird value.
I have generated the below output (see line 40):

1 The total currently '0' (integer) + new TotalSub '-26969.55' type(double) = total '-26969.55'
2 The total currently '-26969.55' (double) + new TotalSub '249.6' type(double) = total '-26730.05'
...
39 The total currently '-164.89' (double) + new TotalSub '61.95' type(double) = total '-112.94'
40 The total currently '-102.94' (double) + new TotalSub '98.71' type(double) = total '-5.3300000000009'
41 The total currently '-5.3300000000009' (double) + new TotalSub  '50' type(double) = total '45.769999999999'

The PHP generating is:

echo ($count++) . " The total currently '$totalTrans' (".gettype($totalTrans).") + new TotalSub '$totalVar' type(".gettype($totalVar).") = total '" . ($totalTrans + $totalVar) ."'<br />";

How can I fix the 00000000009?

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1 Answer

  1. Editorial Team

    From what I can see.
    Try multiplying the input data by 100 and then dividing the totals by 100 at the end.

    Multiplting by 1 or 10 will most likely not correct it which might be due to the 2 decimals and by using 100 the values are now whole numbers (ints)

    Remember floating-point data types (such as DOUBLE) do not represent exact numbers and are approximate.

    You could use bcmath() for maths calculations in the future as using number_format() is no different than using round() without returning it as a string.
    http://php.net/manual/en/book.bc.php

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