Number addition

[juhasamy]

$x = -0.2;
$x += 0.1; print $x . '<br>';
$x += 0.1; print $x . '<br>';
$x += 0.1; print $x . '<br>';

=>

-0.1
0
0.1

 

 

$x = -0.3;
$x += 0.1; print $x . '<br>';
$x += 0.1; print $x . '<br>';
$x += 0.1; print $x . '<br>';
$x += 0.1; print $x . '<br>';

=>

-0.2
-0.1
2.77555756156E-17
0.1

 

???

[adam291086]

What are you trying to do, we can't help without explainations.

[juhasamy]

 

I mean: Is there a bug in PHP?

[adam291086]

i am not sure.

 

Is it supposed to text the value $x and add whatever number and then print it out?

[kenrbnsn]

You're dealing with the classic problem of converting a floating point number from the internal representation in binary to decimal. The value "2.77555756156E-17" is really zero for all pratical purposes.

 

It's not a bug in PHP, it's just how computers work...

 

Ken

[adam291086]

OH i see now, i thoght it was werid. Everything looked right. I learn so much from this board. More than what i have learned in my degree.     

[juhasamy]

 

Thanks.