Summing values from JSON file in PHP

Question

I have a JSON file which looks like this:

[{
    "num": "37"
}, {
    "num": "79"
}, {
    "num": "21"
}, {

    "num": "12"
}, {
    "num": "90"
}]

I need my script to print the sum of these numbers, here is what I tried:

<?php 
$dati = file_get_contents('data.json');
$elementi = json_decode($dati, true);
$test = 'test';

$sum = 0;
foreach($elementi['num'] as $key=>$value)
{
   $sum+= $value;
}


?>

But I got the error:

Notice: Undefined index: num in C:\xampp\htdocs\index.php on line 32

Warning: Invalid argument supplied for foreach() in C:\xampp\htdocs\index.php on line 32

I'm stuck here and I can't find a solution. Can someone please help me?

It was a typo, corrected it

Jack022
– Jack022

2019-02-19 10:39:30 +00:00
Commented Feb 19, 2019 at 10:39 — Jack022
– Jack022, Commented Feb 19, 2019 at 10:39

ArtisticPhoenix · Accepted Answer · 2019-02-19 10:41:58Z

4

I would do

 $sum = array_sum(array_column($arr, 'num'));

But that is just me...

Result

Sandbox

Array column, sucks out all the values for "key" ('num' in this case) and creates an array like this:

   ["37", "79", ...]

Then Array Sum, will give you the sum of an array of numbers.

answered Feb 19, 2019 at 10:41

ArtisticPhoenix

21.7k2 gold badges27 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

RiggsFolly · Accepted Answer · 2019-02-19 10:41:03Z

1

You should always start with a print_r() of the array if you are not sure of its shape and content.

foreach($elementi as $arr)
{
   $sum+= $arr['num'];
}

edited Feb 19, 2019 at 10:41

answered Feb 19, 2019 at 10:40

RiggsFolly

94.7k22 gold badges108 silver badges152 bronze badges

3 Comments

Jack022 Over a year ago

Yes, i made it work with your same solution 1 second before your answer! I'll accept your answer soon, thank you :)

Sayed Mohd Ali Over a year ago

declare $sum before using it in foreach, otherwise, you will get undefined variable notice error.

RiggsFolly Over a year ago

@SayedMohdAli The OP's original code already did that, so as I only suggested a mod to the loop code I did not include that in my code

Samuel Su · Accepted Answer · 2019-02-19 10:47:43Z

0

You can use function array_sum
php version with:PHP 5 >= 5.5.0

$sum = array_sum(array_column($elementi, 'num'));

answered Feb 19, 2019 at 10:47

Samuel Su

11 silver badge1 bronze badge

Collectives™ on Stack Overflow

Summing values from JSON file in PHP

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related