Get the sum of digits in PHP

Question

How do I find the sum of all the digits in a number in PHP?

Answer 1

Assume you want to find the sum of the digits of a number say 2395 the simplest solution would be to first split the digits and find out the sum then concatenate all the numbers into one single number.

<?php
    $number=2;
    $number1=3;
    $number2=9;
    $number3=5;
    $combine=$number.$number1.$number2.$number3;
    $sum=$number+$number1+$number2+$number3;
    echo "The sum of $combine is $sum";
     ?>

Answer 2

// math before code 

// base of digit sums is 9 

// the product of all numbers multiplied by 9 equals 9 as digit sum

$nr = 58821.5712; // any number

// Initiallization 

$d = array();

$d = explode(".",$nr); // cut decimal digits

$fl = strlen($d[1]); // count decimal digits

$pow = pow(10 ,$fl); // power up for integer

$nr = $nr * $pow; // make float become integer

// The Code

$ds = $nr % 9; // modulo of 9 

if($ds == 0) $ds=9; // cancel out zeros

echo $ds;

Answer 3

Artefactos method is obviously unbeatable, but here an version how one could do it "manually":

$number = 1234567890;
$sum = 0;
do {
    $sum += $number % 10;
}
while ($number = (int) $number / 10);

This is actually faster than Artefactos method (at least for 1234567890), because it saves two function calls.

Answer 4

array_sum(str_split($number));

This assumes the number is positive (or, more accurately, that the conversion of $number into a string generates only digits).

Answer 5

Another way, not so fast, not single line simple

<?php

    $n = 123;
    $nstr = $n . "";

    $sum = 0;
    for ($i = 0; $i < strlen($nstr); ++$i)
    {
        $sum += $nstr[$i];
    }
    echo $sum;

?>

It also assumes the number is positive.

Answer 6

function addDigits($num) {

    if ($num % 9 == 0 && $num > 0) {
        return 9;
    } else {
          return $num % 9;
        }
    }

only O(n)

at LeetCode submit result： Runtime: 4 ms, faster than 92.86% of PHP online submissions for Add Digits. Memory Usage: 14.3 MB, less than 100.00% of PHP online submissions for Add Digits.