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

Less code:

$str = "1.1234567";
echo (int) strpos(strrev($str), ".");

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

This will work for any numbers, even in scientific notation, with precision up to 100 decimal places.

$float = 0.0000005;

$working = number_format($float,100);
$working = rtrim($working,"0");
$working = explode(".",$working);
$working = $working[1];

$decmial_places = strlen($working);

Result:

7

Lengthy but works without complex conditionals.

Answer 4

If you want readability for the benefit of other devs, locale safe, use:

function countDecimalPlacesUsingStrrpos($stringValue){
    $locale_info = localeconv();
    $pos = strrpos($stringValue, $locale_info['decimal_point']);
    if ($pos !== false) {
        return strlen($stringValue) - ($pos + 1);
    }
    return 0;
}

see localeconv

Answer 5

You should always be careful about different locales. European locales use a comma for the thousands separator, so the accepted answer would not work. See below for a revised solution:

 function countDecimalsUsingStrchr($stringValue){
        $locale_info = localeconv();
        return strlen(substr(strrchr($stringValue, $locale_info['decimal_point']), 1));
    }

see localeconv

Answer 6

First I have found the location of the decimal using strpos function and increment the strpos postion value by 1 to skip the decimal place.

Second I have subtracted the whole string length from the value I have got from the point1.

Third I have used substr function to get all digits after the decimal.

Fourth I have used the strlen function to get length of the string after the decimal place.

This is the code that performs the steps described above:

     <?php
        $str="98.6754332";
        echo $str;
        echo "<br/>";
        echo substr( $str, -(strlen($str)-(strpos($str, '.')+1)) );
        echo "<br/>";
        echo strlen( substr( $str, -(strlen($str)-(strpos($str, '.')+1))) );
    ?>

Answer 7

I needed a solution that works with various number formats and came up with the following algorithms:

// Count the number of decimal places
$current = $value - floor($value);
for ($decimals = 0; ceil($current); $decimals++) {
    $current = ($value * pow(10, $decimals + 1)) - floor($value * pow(10, $decimals + 1));
}

// Count the total number of digits (includes decimal places)
$current = floor($value);
for ($digits = $decimals; $current; $digits++) {
    $current = floor($current / 10);
}

Results:

input:    1
decimals: 0
digits:   1

input:    100
decimals: 0
digits:   3

input:    0.04
decimals: 2
digits:   2

input:    10.004
decimals: 3
digits:   5

input:    10.0000001
decimals: 7
digits:   9

input:    1.2000000992884E-10
decimals: 24
digits:   24

input:    1.2000000992884e6
decimals: 7
digits:   14

Answer 8

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 9

Here's a function that takes into account trailing zeroes:

function get_precision($value) {
    if (!is_numeric($value)) { return false; }
    $decimal = $value - floor($value); //get the decimal portion of the number
    if ($decimal == 0) { return 0; } //if it's a whole number
    $precision = strlen($decimal) - 2; //-2 to account for "0."
    return $precision; 
}

Answer 10

$value = 182.949;

$count = strlen(abs($value - floor($value))) -2; //0.949 minus 2 places (0.)

Answer 11

<?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 12

How about this?:

$iDecimals = strlen($sFull%1);

Answer 13

I used the following to determine whether a returned value has any decimals (actual decimal values, not just formatted to display decimals like 100.00):

if($mynum - floor($mynum)>0) {has decimals;} else {no decimals;} 

Answer 14

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 15

$decnumber = strlen(strstr($yourstr,'.'))-1

Answer 16

$str = "1.23444";
print strlen(substr(strrchr($str, "."), 1));

Answer 17

Something like:

<?php

$floatNum = "120.340304";
$length = strlen($floatNum);

$pos = strpos($floatNum, "."); // zero-based counting.

$num_of_dec_places = ($length - $pos) - 1; // -1 to compensate for the zero-based count in strpos()

?>

This is procedural, kludgy and I wouldn't advise using it in production code. But it should get you started.

Answer 18

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