How to determine array in php

PHP is a very popular server-side programming language, in which arrays are a very important data structure. In PHP, we often need to determine the type, length, whether it is empty, etc. of an array. This article will introduce how to judge an array.

1. Determine the type of array

Use PHP's built-in function is_array() to determine whether a variable is an array. This function returns true if the variable is an array, otherwise it returns false. The code is as follows:

$arr = array("apple", "banana", "orange");
if (is_array($arr)) {
    echo "arr is an array";
} else {
    echo "arr is not an array";
}

The output result is: arr is an array.

2. Judge the length of the array

Use PHP’s built-in function count() to return the number of elements in an array. The code is as follows:

$arr = array("apple", "banana", "orange");
$num = count($arr);
echo "The array has " . $num . " elements.";

The output result is: The array has 3 elements..

3. Determine whether an array is empty

Use PHP's built-in function empty() to determine whether an array is empty. If the array does not exist or the number of elements is 0, it returns true, otherwise it returns false. The code is as follows:

$arr1 = array();
$arr2 = array("apple", "banana", "orange");
if (empty($arr1)) {
    echo "arr1 is empty";
} else {
    echo "arr1 is not empty";
}
if (empty($arr2)) {
    echo "arr2 is empty";
} else {
    echo "arr2 is not empty";
}

The output result is: arr1 is empty, arr2 is not empty.

4. Determine whether an array contains a certain element

Use PHP's built-in function in_array() to determine whether an array contains a certain element. This function requires two parameters, the first parameter is the element to be judged, and the second parameter is the array to be judged. Returns true if the element exists in the array, false otherwise. The code is as follows:

$arr = array("apple", "banana", "orange");
if (in_array("banana", $arr)) {
    echo "The array contains banana";
}

The output result is: The array contains banana.

5. Determine whether an array is full of numbers

Using PHP's built-in function array_filter() can filter the elements in an array and return it according to our own needs a new array. In this example, we will filter the original array to only return elements that are numbers, and then compare whether the number of elements in the filtered array is equal to the number of elements in the original array to determine whether the original array only contains numbers. The code is as follows:

$arr1 = array(1, 2, 3, 4, 5);
$arr2 = array(1, 2, 'a', 4, 5);
$filtered1 = array_filter($arr1, 'is_numeric');
$filtered2 = array_filter($arr2, 'is_numeric');
if (count($arr1) == count($filtered1)) {
    echo "arr1 contains only numbers";
} else {
    echo "arr1 contains non-numeric values";
}
if (count($arr2) == count($filtered2)) {
    echo "arr2 contains only numbers";
} else {
    echo "arr2 contains non-numeric values";
}

The output result is: arr1 contains only numbers, arr2 contains non-numeric values.

The above are several methods of judging arrays in PHP. I hope it will be helpful to readers.

The above is the detailed content of How to determine array in php. For more information, please follow other related articles on the PHP Chinese website!