CODEWITHSUNDEEP
phpfloating-point
guillaume
guillaume

Reputation: 1678

Weird result when converting string to float

I want to convert a string to float but I've some problem. Here is my code

    $dataValue = $item[$data];
    $dataValue = trim($dataValue);
    var_dump($dataValue);echo "<br>";
    $dataValue = str_replace(',', '.', $dataValue);
    var_dump($dataValue);echo "<br>";
    var_dump(floatval($dataValue));echo "<br>";
    var_dump(floatval('4.02'));echo "<br>";

And the results

string(7) "4,02"
string(7) "4.02"
float(4)
float(4.02)

I don't understand the third result, why I have 4 and not 4.02 ?

Thanks

EDIT:

My new code : 

$dataValue = $item[$data];

        echo mb_detect_encoding($dataValue) . "<br>";

        $dataValue = iconv('ASCII', 'UTF-8//TRANSLIT', $dataValue);
        $dataValue = trim($dataValue);
        $dataValue = str_replace(',', '.', $dataValue);

        echo mb_detect_encoding($dataValue) . "<br>";

        var_dump($dataValue);echo"<br >";
        $dataValue = mb_convert_encoding($dataValue, "UTF-8");
        var_dump($dataValue);echo"<br >";
        $dataValue = str_replace(',', '.', $dataValue);
        $dataValue = floatval($dataValue);
        var_dump($dataValue);echo"<br >";`

And the result

ASCII
ASCII
string(7) "4.02"
string(7) "4.02"
float(4)

Upvotes: 3

Views: 472

Answers (5)

Bogdan Burym
Bogdan Burym

Reputation: 5512

Tested this:

$dataValue = "4,02";
$dataValue = trim($dataValue);
var_dump($dataValue);echo "<br>";
$dataValue = str_replace(',', '.', $dataValue);
var_dump($dataValue);echo "<br>";
var_dump(floatval($dataValue));echo "<br>";
var_dump(floatval('4.02'));echo "<br>";

Output:

string(4) "4,02"
string(4) "4.02"
float(4.02)
float(4.02)

Are you sure that the posted code produces the described problem?

EDIT

Try add this this:

$dataValue = preg_replace("/[^0-9\,]/", '', $dataValue);

Upvotes: 0

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 798566

There are only 4 visible characters, yet var_dump() claims that there are 7. I surmise that there is an invisible character before the decimal point that is causing floatval() to terminate conversion prematurely. You can verify this by looking at a hex dump of the contents of $dataValue.

EDIT:

It appears that your string is encoded in UTF-16LE. Use mb or iconv to convert it to ASCII/UTF-8 before processing.

Upvotes: 5

Erik
Erik

Reputation: 12858

I am going to assume it has to do with accuracy issues in PHP's float implementation.

Check out this: Wikipedia: Floating Point Accuracy Problems

Upvotes: 0

Southpaw Hare
Southpaw Hare

Reputation: 1593

I believe the difference lies in the fast that $dataValue is a double-quoted string in the third output, while you use a single-quoted string in the fourth example. In PHP, these work differently when dealing with how they are treated as literals.

Upvotes: 0

mallix
mallix

Reputation: 1429

Use number_format(float_number, decimal_places): 

var_dump(number_format(floatval($dataValue) ,2));

Upvotes: 0

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