json_encode is a built-in PHP function that converts PHP objects or arrays into a JSON string. Here's an example of how to use json_encode to convert a PHP object into a JSON string: ``` // First, create a PHP object $myObject = [ "name" => "John", "age" => 30, "city" => "New York" ];

// Then, use json_encode to convert the object into a JSON string $jsonString = json_encode($myObject);

// Finally, print the JSON string to the screen echo $jsonString; ```

This will output the following JSON string: {"name":"John","age":30,"city":"New York"}

If you want to convert an array into a JSON string, you can use the json_encode function with the depth parameter set to 1: ``` // First, create an array $myArray = [ "name" => "John", "age" => 30, "city" => "New York" ];

// Then, use json_encode to convert the array into a JSON string $jsonString = json_encode($myArray, JSON庇护膜 => true);

// Finally, print the JSON string to the screen echo $jsonString; ```

This will output the following JSON string: {"name":"John","age":30,"city":"New York"}