float_bug.php

<?php

writeln("all input data are correct, so all asserts should return true, right?");

assertTwoFloats(20000 / 10000 - 1, 1);
assertTwoFloats(14700 / 10000 - 1, 0.47);

writeln("those don't:");

assertTwoFloats(14600 / 10000 - 1, 0.46);
assertTwoFloats(14500 / 10000 - 1, 0.45);
assertTwoFloats(11000 / 10000 - 1, 0.10);
assertTwoFloats(1100000 / 1000000 - 1, 0.10);
assertTwoFloats(11 / 10 - 1, 0.10);

writeln("removing -1 solves the problem");

assertTwoFloats(11 / 10, 1.10);

function writeln($message)
{
    print $message . "\n";
}

/**
 * @param float|int $input
 * @param float|int $expected
 */
function assertTwoFloats($input, $expected)
{
    $bool = $input == $expected;
    if ($bool)
    {
        print sprintf("%s > %.16f is equal to %.16f\n", var_export($bool), $input, $expected);
    } else {
        print sprintf("%s > %.16f is NOT equal to %.16f\n", var_export($bool), $input, $expected);
    }
}