PHP floor function problem.-PHP Tutorial-php.cn

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I am currently writing a project about finance. There are a lot of decimal issues involved. Once when I used floor to round down to two decimal places, I suddenly found that the following code was abnormal.

$money=271.28; echo $money=floor($money*pow(10,2))/100

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I was surprised to find that the output was not 271.28 but 271.27!

Later I checked a lot of information and saw this on the php official website:

The precision of floating point numbers is limited, can be accurately expressed in decimal Rational numbers such as 0.1 or 0.7 , no matter how many mantissas there are, cannot be accurately represented by the binary used internally, and therefore cannot be converted to binary format without losing a little bit of precision. This can lead to confusing results: for example, floor((0.1+0.7)*10) will usually return 7 instead of the expected 8 , because the internal representation of the result is actually It is similar to 7.99999999999999991118... . So never believe that the floating point number result is accurate to the last digit, and never compare whether two floating point numbers are equal.

Later I printed the result of the above operation:

printf("%.12f", $money*pow(10,2));

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found that the result was: 27127.999999999996

It turned out to be an accuracy problem. No unified solution has been found yet. I can only add

if ($money - round ( $money, 2 ) < 0.00001) { }else{ $money=floor($money*pow(10,2))/100; }

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to the code logic to avoid reprocessing the data that has been accurate to two digits.

If anyone knows another way to implement the above function (accurate to two decimal places and discard whatever the third digit is), please let me know.

The above introduces the problem of PHP's floor function. , including relevant content, I hope it will be helpful to friends who are interested in PHP tutorials.