Count the number of "columns" in an array (php) - php

Question

I have the following JSON:
[
{
"0":"2019-08-31",
"1":"Bank Exp.",
"2":"AED",
"3":"30",
"4":"",
"5":"BANK FEE 10"
},
{
"0":"2019-08-31",
"1":"Inventory",
"2":"AED",
"3":"122",
"4":"",
"5":"DEPOSIT 10000"
},
{
"0":"2019-08-31",
"1":"Petty Cash",
"2":"AED",
"3":"4999",
"4":"",
"5":"DEPOSIT 10000"
}
]
I am trying to Count the number of elements or columns in the Json. The result should be 6.
I have tried with echo count($data_array); (or sizeof) result is 3 (number of rows). How can I count the "columns" in this Json, taking into account that I must set as number of column the Max number of column a specific row has?
Do I have to use a loop to count or can I do it with a single instruction?

Answer 1

Assuming that some var $json contains the JSON code you have above, you should be aware that the following code will result in an array of objects of type stdClass:
$data_array = json_decode($json);
So $data_array is in fact an array, but it contains objects. As you pointed out, this will return the number of rows in your JSON:
echo sizeof($data_array);
Clearly, the number of columns is not the number of rows. If you want to know the number of columns then you'll need to check one or more rows/objects/elements of your $data_array var. It's expedient to just look at the first element:
$col_count = sizeof($data_array[0]);
HOWEVER, this is going to cause an E_WARNING if $data_array's elements are objects of type stdClass:
PHP Warning: sizeof(): Parameter must be an array or an object that implements Countable in /tmp/foo.php on line 33
You could optionally use the second parameter of the json_decode function which will force PHP to decode every curly bracketed object in your JSON code as an associative array instead of stdClass objects:
$data_array = json_decode($json, TRUE);
$col_count = sizeof($data_array[0]);
This yields a $col_count value of6 which is the correct for the first object in your array. You should consider that later elements in $data_array may have either more or fewer columns, depending on the structure of your data. If you are sure that all elements will have the same number of columns, this is adequate, but if you have messy data, you may need to check every element of your data array to see what the true number of columns is:
$data_array = json_decode($json, TRUE);
$col_count = 0;
foreach($data_array as $row) {
$col_count = max($col_count, sizeof($row));
}
var_dump($col_count);
This will yield a $col_count value which reflects the maximum number of columns encountered in any element of your JSON. Clearly, there may be performance considerations if your JSON contains a large number of elements. It all depends on your JSON data and the nature of your application.
EDIT:
Instead of an explicit foreach loop, I think you can get away with this, but it will still require PHP to loop through your data structure. That said, it'll probably be faster:
$max_col_count = max(array_map("count", $data_array));

Answer 2

count($data_array) counts the number of elements in an array. In your case, is 3. But your array is multidimensional (matrix). So you need to count on some index to get the number of columns on that position:
<?php
echo count($data_array[0]);