log(1000, 100) does not return 1.5

Question

When I run this code:

$value = log(1000, 100);

echo $value;

if ($value == 1.5) {
    echo 'Equal';
} else {
    echo 'Not Equal';
}

I see 1.5Not Equal. This is very strange because log(1000, 100) does return 1.5, but it does not match the if statement.

Why does PHP do this?

Does this answer your question? [Compare floats in php](https://stackoverflow.com/questions/3148937/compare-floats-in-php) — Gaurav, Feb 25 '22 at 11:36

score 0 · Accepted Answer · answered Feb 24 '22 at 10:56

0

If you var_dump your $value you will see the result is float(1.4999999999999998) and that is not equal to 1.5, you need to use round like:

$value = round(log(1000, 100), 1);

if ($value == 1.5) {
    echo 'Equal';
} else {
    echo 'Not Equal';
}

Here you can see result.

Reference:

answered Feb 24 '22 at 10:56

Simone Rossaini

But why does PHP do this then? Because log(1000, 100) is clearly 1.5 and not 1.4999999999999998 – Jeroen van Rensen Feb 24 '22 at 11:22
See second reference. – Simone Rossaini Feb 24 '22 at 11:36

1 Answers1