Warning about floating point precision in PHP

Introduction: This is a detailed page of the floating point Precision warning in PHP. It introduces the related knowledge, skills, experience, and some PHP source code.

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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) returns 7 instead of 8.

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

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.

(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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