CODEWITHSUNDEEP
php
cnrhgn
cnrhgn

Reputation: 703

Why is this showing to multiple decimal places?

Why is this not keeping the rounding on the $artWidthCM and $artHeightCM when I am adding it to the object?

If I echo out the values I get what is expected: '0.305'.

But when adding it to $artObj it prints as '0.304999999999999993338661852249060757458209991455078125'.

if ($result->num_rows > 0) {

    $artObj = new stdClass();

    while($row = $result->fetch_assoc()) {

        //Dimensions
        $dimenionsStrip = str_replace(' ', '', $row["Dimensions"]);
        $dimensionsArr = explode("x", $dimenionsStrip);
        $artWidthInch = 12;  // $dimensionsArr[0];
        $artHeightInch = 12;  // $dimensionsArr[1];

        $artWidthCM = (round(($artWidthInch * 2.54) * 2) / 2) / 100;
        $artHeightCM = (round(($artHeightInch * 2.54) * 2) / 2) / 100;

        // Build Object
        $artObj->id = $row["ArtID"];
        $artObj->artwidth = $artWidthCM;
        $artObj->artheight = $artHeightCM;
    }

    $artJSON = json_encode($artObj, JSON_PRETTY_PRINT);
    echo '['.$artJSON.']';

} else {
    echo "No Artwork Found";
}

Prints JSON as follows:

[{ "id": "35628", "artwidth": 0.304999999999999993338661852249060757458209991455078125, "artheight": 0.304999999999999993338661852249060757458209991455078125 }]

On my local machine with exact same code it prints as:

[{ "id": "35628", "artwidth": 0.305, "artheight": 0.305 }]

Upvotes: 0

Views: 47

Answers (1)

Filip Halaxa
Filip Halaxa

Reputation: 778

This is a problem of floating point precision. See the Warning at https://www.php.net/manual/en/language.types.float.php

Highlight from the link:

So never trust floating number results to the last digit, and do not compare floating point numbers directly for equality. If higher precision is necessary, the arbitrary precision math functions and gmp functions are available.

The floating point handling may be different on different machines, that's why it behaves "correctly" on one and "incorrectly" on other.

Upvotes: 1

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