The problem of PHP module taking

I asked a friend and found a problem: when floating p>< is converted to integer:

<; ? php

$a = 9.45*1;

var_dump($a);

var_dump(intval($a));

$a = 945*1.;

var_dump($a);

var_dump(intval($a)); >

the running results are as follows:

float (945) int (944) float (945) int (945)

both are floating-point 945, one is converted to 944 and the other is converted to 955

Obviously, a simple decimal fraction like .1 or .7 cannot be converted into internal binary without losing a little precision. This will lead to confusing results: for example, floor((.1+.7)*1) usually returns 7 instead of the expected 8, because the internal representation of the result is actually similar to 7.9999 ...

This is related to the fact that it is impossible to accurately express some decimal fractions with finite digits. For example, 1/3 of the decimal system becomes .3333333.

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.

that is to say, 9.45*1 is similar to 944.9999

I hope the above explanation can help you. .