PHP: get number of decimal digits

Question

Is there a straightforward way of determining the number of decimal places in a(n) integer/double value in PHP? (that is, without using explode)

Answer 1

<?php

test(0);
test(1);
test(1.234567890);
test(-123.14);
test(1234567890);
test(12345.67890);

function test($f) {
    echo "f = $f\n";
    echo "i = ".getIntCount($f)."\n";
    echo "d = ".getDecCount($f)."\n";
    echo "\n";
}

function getIntCount($f) {
    if ($f === 0) {
        return 1;
    } elseif ($f < 0) {
        return getIntCount(-$f);
    } else {
        return floor(log10(floor($f))) + 1;
    }
}

function getDecCount($f) {
    $num = 0;
    while (true) {
        if ((string)$f === (string)round($f)) {
            break;
        }
        if (is_infinite($f)) {
            break;
        }

        $f *= 10;
        $num++;
    }
    return $num;
}

Outputs:

f = 0
i = 1
d = 0

f = 1
i = 1
d = 0

f = 1.23456789
i = 1
d = 8

f = -123.14
i = 3
d = 2

f = 1234567890
i = 10
d = 0

f = 12345.6789
i = 5
d = 4

Answer 2

Solution

$num = "12.1234555";
print strlen(preg_replace("/.*\./", "", $num)); // 7

Explanation

Pattern .*\. means all the characters before the decimal point with its.

In this case it's string with three characters: 12.

preg_replace function converts these cached characters to an empty string "" (second parameter).

In this case we get this string: 1234555

strlen function counts the number of characters in the retained string.

Answer 3

How about this?:

$iDecimals = strlen($sFull%1);

Answer 4

function numberOfDecimals($value)
{
    if ((int)$value == $value)
    {
        return 0;
    }
    else if (! is_numeric($value))
    {
        // throw new Exception('numberOfDecimals: ' . $value . ' is not a number!');
        return false;
    }

    return strlen($value) - strrpos($value, '.') - 1;
}


/* test and proof */

function test($value)
{
    printf("Testing [%s] : %d decimals\n", $value, numberOfDecimals($value));
}

foreach(array(1, 1.1, 1.22, 123.456, 0, 1.0, '1.0', 'not a number') as $value)
{
    test($value);
}

Outputs:

Testing [1] : 0 decimals
Testing [1.1] : 1 decimals
Testing [1.22] : 2 decimals
Testing [123.456] : 3 decimals
Testing [0] : 0 decimals
Testing [1] : 0 decimals
Testing [1.0] : 0 decimals
Testing [not a number] : 0 decimals

Answer 5

Int

Integers do not have decimal digits, so the answer is always zero.

Double/Float

Double or float numbers are approximations. So they do not have a defined count of decimal digits.

A small example:

$number = 12.00000000012;
$frac = $number - (int)$number;

var_dump($number);
var_dump($frac);

Output:

float(12.00000000012)
float(1.2000000992884E-10)

You can see two problems here, the second number is using the scientific representation and it is not exactly 1.2E-10.

String

For a string that contains a integer/float you can search for the decimal point:

$string = '12.00000000012';
$delimiterPosition = strrpos($string, '.');
var_dump(
  $delimiterPosition === FALSE ? 0 : strlen($string) - 1 - $delimiterPosition
);

Output:

int(11)

Answer 6

You could try casting it to an int, subtracting that from your number and then counting what's left.