How to check the dimensionality of an array in php

php method to check whether an array is a several-dimensional array: 1. Using loop recursion judgment, you can write a recursive function to traverse the array, and call the same function recursively when encountering a nested array. When it is not an array element, return the number of currently traversed layers; 2. Use the "array_filter" function to compare whether the total number of elements of the array and the recursion count are equal. If they are not equal, it means that the array is a multi-dimensional array; 3. Use array_walk_recursive function etc.

The operating environment of this article: Windows 10 system, php8.1.3 version, dell g3 computer.

In PHP, checking whether an array is a one-dimensional array or a multi-dimensional array is a common task. When dealing with array operations, it is important to understand the dimensions of the array because it affects the methods we use to traverse and manipulate the array.

So how to check whether an array is a one-dimensional array or a multi-dimensional array? Several methods of judgment will be introduced below.

1. Use loop recursion to determine

Using loop recursion is a common method to check the dimensions of an array. You can write a recursive function that iterates over an array and calls the same function recursively when nested arrays are encountered. When a non-array element is encountered, the current level traversed is returned. For example:

function getArrayDepth($array){
$max_depth = 1;
foreach($array as $value){
if(is_array($value)){
$depth = getArrayDepth($value) + 1;
if($depth > $max_depth){
$max_depth = $depth;
}
}
}
return $max_depth;
}

Usage example:

$array1 = [1, 2, 3];
$array2 = [1, [2, 3]];
$array3 = [1, [2, [3]]];
echo getArrayDepth($array1); // 输出1
echo getArrayDepth($array2); // 输出2
echo getArrayDepth($array3); // 输出3

This method traverses the array recursively and calls the same function recursively when encountering a nested array, eventually returning the maximum depth of the array.

2. Use the array_filter function

PHP's array_filter function can filter the elements in the array according to the specified callback function and return the elements that meet the conditions. We can use array_filter function to check if an array has nested arrays.

function isMultiDimensional($array){
return (count($array) !== count($array, COUNT_RECURSIVE));
}

Usage example:

$array1 = [1, 2, 3];
$array2 = [1, [2, 3]];
$array3 = [1, [2, [3]]];
var_dump(isMultiDimensional($array1)); // 输出false
var_dump(isMultiDimensional($array2)); // 输出true
var_dump(isMultiDimensional($array3)); // 输出true

This method determines whether there is a nested array by comparing the total number of elements of the array and the recursion count. If they are not equal, it means that the array is a multidimensional array.

3. Use the array_walk_recursive function

PHP’s array_walk_recursive function can recursively call a user-defined function for each element in the array. We can use this feature to check if an array has nested arrays.

function isMultiDimensional($array){
$result = false;
$callback = function($value) use (&$result){
if(is_array($value)){
$result = true;
}
};
array_walk_recursive($array, $callback);
return $result;
}

Usage example:

$array1 = [1, 2, 3];
$array2 = [1, [2, 3]];
$array3 = [1, [2, [3]]];
var_dump(isMultiDimensional($array1)); // 输出false
var_dump(isMultiDimensional($array2)); // 输出true
var_dump(isMultiDimensional($array3)); // 输出true

This method uses the array_walk_recursive function to traverse each element in the array. When encountering a nested array, set a flag bit to true, and finally return the The value of the flag bit.

The above are three common methods to check whether an array is a one-dimensional array or a multi-dimensional array. Choose the appropriate method according to actual needs to be more flexible and efficient when processing array operations.

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