Floating point precision warning in PHP

The floating point precision warning in PHP is a prompt in PHPdocument: a simple decimal score is like 0.1 or 0.7 and cannot be converted to an internal binary format without losing a little precision. Floor (0.1 + 0.7) * 10 )?? Returns a warning of the floating point precision of 7 instead of PHP.

This is the prompt in PHP document:

A simple decimal score is like0.1Or0.7It cannot be converted to an internal binary format without losing a little bit of precision.

Floor (0.1 + 0.7) * 10)? ? Return7Instead8,

(Int) (0.1 + 0.7) * 10 )? Return 7 instead of 8.

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The explanation for this phenomenon is "because the internal representation of the result is actually similar.7.9 ".

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So the conclusion is:

Therefore, never believe that the result of a floating point number is accurate to the last digit, or compare whether the two floating points are equal.

Never forcibly convert an unknown score to an Int.

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(Int) round (0.1 + 0.7) * 10) this seems safe.

The BC math function is used for numerical accuracy when a large number of multiplication or division is performed or the center value is float.

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