How to save a two-dimensional array in php (methods and tips)

PHP is a server-side scripting language widely used in web development. In PHP, an array is an important data type that can store multiple values, including numbers, strings, or objects. In some cases, we need to combine multiple values ​​into a two-dimensional array to meet specific business needs. This article will explore how PHP saves two-dimensional arrays and introduce some methods and techniques.

1. Introduction to two-dimensional arrays

In PHP, a two-dimensional array is an array containing multiple arrays, and each array contains multiple key-value pairs (or elements). For example, the following code demonstrates how to create a simple two-dimensional array:

$grades = array(
    array("Tom", 80),
    array("John", 90),
    array("Mary", 95)
);

In the above code, $grades is an array containing 3 arrays, and each array contains 2 key-value pairs. The first array contains the key-value pair ("Tom", 80), the second array contains the key-value pair ("John", 90), and the third array contains the key-value pair ("Mary", 95).

2. Saving a two-dimensional array

When we need to save a two-dimensional array, we can use different methods and techniques. Here are a few common examples.

1. Save the two-dimensional array as a string

We can use PHP's serialization function serialize() to convert the two-dimensional array into a string and save it in file or database. When needed, we can use the deserialization function unserialize() to restore the string to a two-dimensional array. For example, the following code demonstrates how to save the two-dimensional array $grades to a file:

$serialized_grades = serialize($grades);
file_put_contents("grades.txt", $serialized_grades);

In the above code, we use the serialization function serialize() to convert the $grades array into the string $serialized_grades, and use the function file_put_contents() saves the string to the file "grades.txt".

When reading a file, we can use the function file_get_contents() to read the string in the file, and use the deserialization function unserialize() to restore the string to a two-dimensional array. For example, the following code demonstrates how to read a saved two-dimensional array from a file:

$serialized_grades = file_get_contents("grades.txt");
$grades = unserialize($serialized_grades);

In the above code, we use the function file_get_contents() to read the string $serialized_grades in the file "grades.txt", And use the deserialization function unserialize() to restore the string to the two-dimensional array $grades.

2. Save the two-dimensional array as JSON

We can also use PHP's JSON function json_encode() to convert the two-dimensional array into JSON format and save it in a file or in the database. When needed, we can use the JSON function json_decode() to restore the JSON format string to a two-dimensional array. For example, the following code demonstrates how to save the two-dimensional array $grades to a file:

$json_grades = json_encode($grades);
file_put_contents("grades.json", $json_grades);

In the above code, we use the JSON function json_encode() to convert the two-dimensional array $grades into a JSON format string $json_grades, And use the function file_put_contents() to save the string to the file "grades.json".

When reading a file, we can use the function file_get_contents() to read the JSON format string in the file, and use the JSON function json_decode() to restore the JSON format string into a two-dimensional array. For example, the following code demonstrates how to read a saved two-dimensional array from a file:

$json_grades = file_get_contents("grades.json");
$grades = json_decode($json_grades, true);

In the above code, we use the function file_get_contents() to read the JSON format string in the file "grades.json" $ json_grades, and use the JSON function json_decode() to restore the JSON format string to the two-dimensional array $grades.

3. Save the two-dimensional array to the database

We can use PHP database extensions such as MySQLi or PDO to save the two-dimensional array to the database. For example, the following code demonstrates how to save the two-dimensional array $grades to a MySQL database:

$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败：" . $conn->connect_error);
}

// 创建SQL语句
$sql = "INSERT INTO grades (name, score)
VALUES (?, ?)";

// 准备SQL语句
$stmt = $conn->prepare($sql);

// 绑定参数并执行SQL语句
foreach ($grades as $grade) {
    $name = $grade[0];
    $score = $grade[1];
    $stmt->bind_param("si", $name, $score);
    $stmt->execute();
}

$stmt->close();
$conn->close();

In the above code, we use the MySQLi extension to create the database connection $conn, and use the SQL statement INSERT INTO to convert the two-dimensional array into $grades is saved to table grades. We first prepare the SQL statement using the function prepare() and bind the parameters using the function bind_param(). Then, we use a foreach loop to traverse the two-dimensional array $grades and insert $name and $score into the table grades.

When we need to read the saved two-dimensional array, we can use the SQL statement SELECT and fetch functions to read relevant data from the database.

3. Summary

In PHP, we can use different methods and techniques to save two-dimensional arrays of multiple values, including saving the array as a string, JSON format or in a database. These techniques can meet different business needs and improve the readability and maintainability of the program. In actual development, we choose appropriate storage methods based on business needs and performance requirements to improve the efficiency and quality of the program.

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