


How to count the number of occurrences of a specific subscript in a 2D array in PHP?
Apr 01, 2025 pm 12:03 PMEfficiently count the number of occurrences of specific subscript values ??in PHP two-dimensional arrays
This article introduces an efficient method to count the number of occurrences of a specific subscript value in a PHP two-dimensional array. Suppose we have a two-dimensional array, each subarray contains three key-value pairs, id
, name
and age
, and we need to count the number of elements with age
value of 18.
Here is an example two-dimensional array:
$array = [ ['id' => 1, 'name' => 'A', 'age' => 19], ['id' => 2, 'name' => 'B', 'age' => 20], ['id' => 3, 'name' => 'C', 'age' => 18], ['id' => 5, 'name' => 'D', 'age' => 18], ['id' => 6, 'name' => 'E', 'age' => 18] ];
We can use the array_reduce
function to implement statistics concisely:
$count = array_reduce($array, function ($carry, $item) { return $item['age'] === 18 ? $carry : $carry; }, 0); echo "There are {$count} elements with age of 18."; // Output: There are 3 elements with age of 18.
The array_reduce
function passes each element in the array $array
to the anonymous function in turn. The anonymous function checks whether age
is equal to 18, and if so, the accumulator $carry
is added to 1; otherwise, $carry
remains unchanged. The initial value is 0. Finally, array_reduce
returns the value of the accumulator, that is, the number of elements with age
of 18.
This approach is simpler and more efficient than using foreach
loops, especially when dealing with large arrays, with more obvious performance advantages. You can modify $item['age'] === 18
part to count the values ??of other subscripts as needed. For example, to count the number of elements with id
3, just modify the part to $item['id'] === 3
.
The above is the detailed content of How to count the number of occurrences of a specific subscript in a 2D array in PHP?. For more information, please follow other related articles on the PHP Chinese website!

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