当$ balance高于0.01时，为什么$ if语句中的$ balance不等于0.01？ [重复]

Question

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• Is floating point math broken? 30 answers

I have a problem with an if statement. The program doesn't go inside the if when it seems that the condition is true.

I tried to change the operator >= to == but it still doesn't work. It works with <= but I need >= and I also can't explain to myself why it's not working.

<?php

$balance = 0.03;      // input 0.03 

if($balance >= 0.02)
{
    $returned = ((floor($balance / 0.02)) * 0.02); // 0.02
    $balance = $balance - $returned;               // 0.03 - 0.02 = 0.01 left
}

echo var_dump($balance) . PHP_EOL;

if($balance >= 0.01)                // why doesnt go in ?
{
    echo "Print Smt ....";
}

Why is the second if not true? Isn't 0.01 equal to 0.01?

</div>

Answer 1

Because $balance is reassigned value -1.47 which is less than 0.01.