How to use PHP array loop to convert to JSON format

In PHP development, it is often necessary to transmit data to the front end, and the transmitted data usually needs to be presented in JSON format. PHP array is a very commonly used data structure. It is very convenient to convert PHP array into JSON format. This article will introduce how to use PHP array loop to convert into JSON format.

1. What is JSON

JSON (JavaScript Object Notation) is a lightweight data exchange format whose syntax is the same as JavaScript object notation. JSON is a text format that is easy to read and write, and easy to port and parse. JSON data can be passed between different programming languages.

1. PHP array

PHP array is a very common data structure used to store a set of related data. It can be a numeric index array or an associative array. . PHP arrays make it easy to add, remove and modify elements.

For example, the following is a PHP associative array:

$person = array(
    "name" => "John",
    "age" => 30,
    "city" => "New York"
);

In the above array, each element has a key and a value. The key can be a string or an integer, and the value can be any type of data.

1. Use PHP array to convert to JSON

There is a built-in function in PHP json_encode(), which is used to convert PHP array to JSON format. The following is an example code of how to use the json_encode() function to convert a PHP array into JSON format:

$person = array(
    "name" => "John",
    "age" => 30,
    "city" => "New York"
);

$json_data = json_encode($person);

echo $json_data;   // 输出 {"name":"John","age":30,"city":"New York"}

The above code uses the json_encode() function to convert an associative array$personConvert to JSON format and store it in the variable $json_data. Finally, use the echo function to output data in JSON format.

1. Loop PHP array

The elements in the PHP array can be traversed using foreach. The following is an example code of how to use foreach to loop through a PHP associative array:

$person = array(
    "name" => "John",
    "age" => 30,
    "city" => "New York"
);

foreach ($person as $key => $value) {
    echo $key . " : " . $value . "
";
}

The above code will use foreach to loop through a PHP associative array$person for each element and prints the element's key and value on the screen.

1. Loop to convert PHP array to JSON

Now we already know how to use the json_encode() function to convert a PHP array to JSON format, And how to use foreach to loop through an associative array in PHP. We can combine them and use a loop to convert each element in the PHP array into JSON format.

The following is a sample code that loops through a PHP associative array into JSON format:

$person = array(
    "name" => "John",
    "age" => 30,
    "city" => "New York"
);

$json_data = "{";

foreach ($person as $key => $value) {
    if ($json_data != "{") {
        $json_data .= ",";
    }
    $json_data .= '"' . $key . '":"' . $value . '"';
}

$json_data .= "}";

echo $json_data;   // 输出 {"name":"John","age":30,"city":"New York"}

The above code loops through each element of the PHP associative array $person, and converts It is converted into JSON format, and finally the JSON strings of all elements are concatenated. Please note that when splicing JSON strings, we need to surround the key of the element with double quotes ", and the value of the element with double quotes ".

1. Summary

In this article, we introduced how to use PHP array loop to convert data into JSON format. We first learned about the concept of JSON and then learned the basics of PHP arrays. Next, we learned how to use the json_encode() function to convert the PHP array into JSON format, and use the foreach method to loop through the PHP associative array. Finally, we combine loop traversal and JSON format, using loops to convert the elements in the PHP array into JSON format.

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