PHP query array specified value position

In PHP, array is a very common and powerful data type. In the process of using PHP arrays, one of the most common operations is to query the position of a specified value in the array. This article will introduce several different ways to achieve this operation.

Method 1: Use the array_search() function

The array_search() function is one of PHP's built-in functions, used to find a specified value in an array and return the key name of the value. Using this function is very simple. You only need to pass in two parameters. The first is the value to be found, and the second is the array. The function will search for the specified value in the array and return its key name.

The following is a sample code:

$fruits = array("apple", "banana", "orange");
$key = array_search("banana", $fruits);
echo "The key of banana is: " . $key;  //输出：The key of banana is: 1

Method 2: Use the in_array() function and array_keys() function

In addition to the array_search() function, PHP also provides two Two functions, namely in_array() function and array_keys() function, can also be used to query the position of a specified value in an array.

The in_array() function is used to check whether the specified value exists in the array. If it exists, it returns true, otherwise it returns false. If you need to get the key name of a specified value, you can use the array_keys() function, which returns an array containing all the key names of the specified value.

The following is a sample code:

$fruits = array("apple", "banana", "orange");
if (in_array("banana", $fruits)) {
    $keys = array_keys($fruits, "banana");
    echo "The key of banana is: " . implode(",", $keys);  //输出：The key of banana is: 1
}

Method 3: Use foreach() loop

In addition to using built-in functions, you can also find the location of the specified value by traversing the array , the specific steps are as follows:

1. Use foreach() to loop through the array;
2. In the loop, compare each value of the array with the target value;
3. If the match is successful, the current key name is returned.

The following is a sample code:

$fruits = array("apple", "banana", "orange");
$search = "banana";
foreach ($fruits as $key => $value) {
    if ($search == $value) {
        echo "The key of $search is: " . $key;  //输出：The key of banana is: 1
        break;
    }
}

It should be noted that although this method is more intuitive, searching in large arrays may be time-consuming, so it is not suitable for processing Large array.

Summary:

The above three methods can all be used to query the position of a specified value in a PHP array, among which using the array_search() function is the simplest and fastest method. If you need to get all key names that contain a specified value, you can use the in_array() function combined with the array_keys() function. If you need to find a specific value in a smaller array, you can use loop traversal.

No matter which method is used, it is one of the common array operations. In actual development, it is necessary to choose the most appropriate method to process arrays according to the specific situation.

The above is the detailed content of PHP query array specified value position. For more information, please follow other related articles on the PHP Chinese website!