Number Formatting, Where Do The Extra Decimals Come From?

[Fergal 0]

When I run;

$number = 4675.55555;

$number = number_format ($number, 20);

print $number;

 

it outputs 4,675.55555000000003929017

 

Where do the extra "3929017" digits come from?

 

Thanks!

[Larry 433]

This is a common, although not widely known, aspect of computers: they don't store numbers cleanly. For example, in many languages, this condition would be false:

(1/3 * 3) == 1

 

So internally, PHP is adding those extra digits (or, to be precise, the computer's architecture is).

[Fergal 0]

Thanks Larry. I'm deliberately trying to break the scripts I write now and it has really helped my understanding of the book's content.