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Php if statement issue. Returning wrong result

I have this code that is returning incorrect value.
The result is ‘7 price3’ but it is wrong. 7 should fall on second if statement since $value is greater than 5 and less than or equal to 7. You can try on your php editor and it will return on the third if statement.

$price = 100;
$requestprice = 93;

$value = (($price - $requestprice) / $price) * 100;

if ($value <= 5) {
    echo $value . ' price 1';
} else if ($value > 5 && $value <= 7) {
    echo $value . ' price 2';
} else if ($value > 7 && $value <= 10) {
    echo $value . ' price 3';
}

Tried to run the code on any php editor and still got the wrong result

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2

Answers


  1. 0

    It’s because of floating point imprecision. The actual value of $value isn’t just 7, it’s 7.00000000000000088818. You can see that if you add the following line just after $value = (($price - $requestprice) / $price) * 100;:

    printf("%.20f", $value);

    Since 7.00000000000000088818 is greater than 7, the code is taking the right branch.

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  2. 0

    $value is a float value, convert it to an integer for accurate comparisons. Also, you don’t need repeated comparisons. See also

    <?php

$price = 100;
$requestprice = 93;

$value = intval((($price - $requestprice) / $price) * 100);

if ($value <= 5) {
    echo $value . ' price 1';
} else if ($value <= 7) {
    echo $value . ' price 2';
} else if ($value <= 10) {// or skip this if condition
    echo $value . ' price 3';
}

    Online Demo

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