Convertire una stringa contenente un numero in notazione scientifica per una doppia in PHP

Question

Ho bisogno di aiuto la conversione di una stringa che contiene un numero in notazione scientifica ad un doppio.

stringhe Esempio: "1.8281e-009" "2.3562e-007" "0.911348"

stavo pensando solo rompendo il numero nel numero a sinistra e l'esponente e non solo fare i calcoli per generare il numero; ma c'è un / modo migliore standard per fare questo?

Answer 1

PHP is typeless dynamically typed, meaning it has to parse values to determine their types (recent versions of PHP have type declarations).

In your case, you may simply perform a numerical operation to force PHP to consider the values as numbers (and it understands the scientific notation x.yE-z).

Try for instance

  foreach (array("1.8281e-009","2.3562e-007","0.911348") as $a)
  {
    echo "String $a: Number: " . ($a + 1) . "\n";
  }

just adding 1 (you could also subtract zero) will make the strings become numbers, with the right amount of decimals.

Result:

  String 1.8281e-009: Number: 1.0000000018281
  String 2.3562e-007: Number: 1.00000023562
  String 0.911348:    Number: 1.911348

You might also cast the result using (float)

  $real = (float) "3.141592e-007";

Answer 2

$f = (float) "1.8281e-009";
var_dump($f); // float(1.8281E-9)

Answer 3

$float = sprintf('%f', $scientific_notation);
$integer = sprintf('%d', $scientific_notation);
if ($float == $integer)
{
    // this is a whole number, so remove all decimals
    $output = $integer;
}
else
{
    // remove trailing zeroes from the decimal portion
    $output = rtrim($float,'0');
    $output = rtrim($output,'.');
}

Answer 4

I found a post that used number_format to convert the value from a float scientific notation number to a non-scientific notation number:

http://jetlogs.org/2008/02/05/php-problems-with-big-integers-and-scientific-notation/

Editor's note: Link is rotten

Example from the post:

$big_integer = 1202400000; 
$formatted_int = number_format($big_integer, 0, '.', ''); 
echo $formatted_int; //outputs 1202400000 as expected 

HTH

Answer 5

Following line of code can help you to display bigint value,

$token=  sprintf("%.0f",$scienticNotationNum );

refer with this link.

Answer 6

Use number_format() and rtrim() functions together. Eg

//eg $sciNotation = 2.3649E-8
$number = number_format($sciNotation, 10); //Use $dec_point large enough
echo rtrim($number, '0'); //Remove trailing zeros

I created a function, with more functions (pun not intended)

function decimalNotation($num){
    $parts = explode('E', $num);
    if(count($parts) != 2){
        return $num;
    }
    $exp = abs(end($parts)) + 3;
    $decimal = number_format($num, $exp);
    $decimal = rtrim($decimal, '0');
    return rtrim($decimal, '.');
}

Answer 7

function decimal_notation($float) {
        $parts = explode('E', $float);

        if(count($parts) === 2){
            $exp = abs(end($parts)) + strlen($parts[0]);
            $decimal = number_format($float, $exp);
            return rtrim($decimal, '.0');
        }
        else{
            return $float;
        }
    }

work with 0.000077240388