Convert a string containing a number in scientific notation to a double in PHP
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14-10-2019 - |
Question
I need help converting a string that contains a number in scientific notation to a double.
Example strings: "1.8281e-009" "2.3562e-007" "0.911348"
I was thinking about just breaking the number into the number on the left and the exponent and than just do the math to generate the number; but is there a better/standard way to do this?
Solution
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";
OTHER TIPS
$f = (float) "1.8281e-009";
var_dump($f); // float(1.8281E-9)
$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,'.');
}
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
Following line of code can help you to display bigint value,
$token= sprintf("%.0f",$scienticNotationNum );
refer with this link.
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($decimal, '.');
}
function decimal_notation($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