PHP有一个比较分裂后的bug

Question

I have a problem with PHP comparing after I divide a value float and integer.

Here my code :

<?php

    function test_promo($price) {
        $tmpprice = $price*100;
        $divprice = $tmpprice/intval($tmpprice);
        if ( $divprice > 1 ) {
            echo "$price = TRUE
";
            //TODO do something >1
        }
        else {
            echo "$price = FALSE
";
            //TODO do something <=1
        }
    }

    echo "<pre>";
    test_promo(2.41);   //output--> 2.41 = FALSE
    test_promo(2.42);   //output--> 2.42 = FALSE
    test_promo(2.43);   //output--> 2.43 = TRUE
    test_promo(2.44);   //output--> 2.44 = FALSE
    test_promo(2.45);   //output--> 2.45 = TRUE
    test_promo(2.46);   //output--> 2.46 = FALSE
    test_promo(2.47);   //output--> 2.47 = TRUE
    test_promo(2.48);   //output--> 2.48 = FALSE
    test_promo(2.49);   //output--> 2.49 = TRUE
    echo "</pre>";

?>

As you can see the result must be all FALSE but it's not :S

Is it a bug in PHP or just only my computer (Ubuntu x64) has this bug?

SOLUTION :

As the corrected answer below, I need to get only float number as define (the number after .) like this $divprice = number_format( $newprice/intval($newprice), 2 );

Answer 1

Floating points can not represent exactly the value you posted in decimal. In other words, 2.43 is not really 2.43, but actually [something close to] 2.4300000000000003. So when you divide 243.00000000000003 by 243 the result will be greater than 1.

This is not a bug in PHP, just the way floating point works (in any language). If you need to work with exact decimal values, you'd better search for a specific library to do that. This question might be a good starting point.