How to determine whether it is an indexed array in php

PHP is a multi-purpose programming language that supports a variety of data structures and data types. One of the most basic data types is the array. In PHP, there are two types of arrays: indexed arrays and associative arrays. Indexed arrays use numeric keys to index values ​​in the array, whereas associative arrays use string keys to index values ​​in the array.

In PHP, it is not difficult to determine whether an array is an index array. Below we will introduce three methods to determine whether a PHP array is an index array:

Method 1: Use array_keys() function

array_keys() function returns an array containing all key values ​​in the array new array. If the array is an indexed array, the function will return the numeric keys starting from 0; if the array is an associative array, the function will return all key names. Therefore, by determining whether the key name of the first element is 0, you can determine whether the array is an index array.

The following is an example of using this function to determine whether an array is an index array:

$array = array("apple", "banana", "orange");

if (array_keys($array)[0] === 0) {
    echo "该数组为索引数组";
} else {
    echo "该数组为关联数组";
}

Output:

该数组为索引数组

Method 2: Use the is_int() function

## The #is_int() function determines whether the given variable is an integer. When determining whether an array is an indexed array, we can use this function to determine whether each key in the array is an integer. If all keys are integers, the array is an indexed array; otherwise, the array is an associative array.

The following is an example of using this function to determine whether an array is an index array:

$array = array("apple", "banana", "orange");

$is_index_array = true;
foreach ($array as $key => $value) {
    if (!is_int($key)) {
        $is_index_array = false;
        break;
    }
}

if ($is_index_array) {
    echo "该数组为索引数组";
} else {
    echo "该数组为关联数组";
}

Output:

该数组为索引数组

Method 3: Use the ctype_digit() function

## The #ctype_digit() function determines whether the given string contains only numeric characters. When determining whether an array is an indexed array, we can use this function to determine whether each key in the array is a numeric string. If all keys are numeric strings, the array is an indexed array; otherwise, the array is an associative array.

The following is an example of using this function to determine whether an array is an index array:

$array = array("apple", "banana", "orange");

$is_index_array = true;
foreach (array_keys($array) as $key) {
    if (!ctype_digit((string)$key)) {
        $is_index_array = false;
        break;
    }
}

if ($is_index_array) {
    echo "该数组为索引数组";
} else {
    echo "该数组为关联数组";
}

Output:

该数组为索引数组

The above are three ways to determine whether a PHP array is an index array method. Choosing the appropriate method according to the specific scenario can make the code more concise and efficient.

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