Comparison example analysis of two float (floating point numbers) in PHP_php skills

The example in this article describes two float (floating point number) comparison methods in PHP. Share it with everyone for your reference. The details are as follows:

When I was developing a contract management system recently, it involved comparing two floating point numbers, which made me very depressed.
A long time ago, I didn’t know where I heard the “truth” of “Don’t use the equal sign to compare floating point numbers”. I used it on a daily basis, and it seemed that there was no problem. But this time the problem finally came.

<&#63;php
$sum = "12300.00";
$a  = "10000.30";
$b  = "2000.30";
$c  =  "299.40";
$sum = (float) $sum;
$s = (float) ($a+$b+$c);
var_dump($sum, $s);
var_dump($sum==$s);

The result is:

float(12300)
float(12300)
bool(false)

I later learned that in PHP, to compare the sizes of two floating point numbers, you can use bccomp (parameter 1, parameter 2, decimal places) to compare.

<&#63;php
$sum = "12300.00";
$a  = "10000.30";
$b  = "2000.30";
$c  =  "299.40";
$sum = (float) $sum;
$s = (float) ($a+$b+$c);
var_dump($sum, $s);
var_dump(bccomp($sum,$s,2));

Result:

float(12300)
float(12300)
int(0) // 0 means two floating point values ​​are equal

For specific usage of the bccomp function, please refer to the PHP manual.

I hope this article will be helpful to everyone’s PHP programming design.