Use PHP to access and parse API return data

With the development and popularization of the Internet, various applications have an increasing demand for data. In order to obtain more data, third-party APIs (Application Programming Interface) are increasingly used. API refers to some instructions or interfaces provided by an application that can be used to access the back-end data of an application. In this article, we will explain how to access and parse the return data of the API using PHP.

1. What is API

API is an abbreviation, the full name is Application Programming Interface, which translates to application programming interface. It usually refers to some interfaces of a software or service that allow other software or services to access its back-end data or functions. APIs are for developers and usually communicate through the HTTP (Hypertext Transfer Protocol) protocol.

Using API can help us obtain some open data, query some services, obtain some resources, etc. For example, we can use the weather API to access weather data (temperature, wind speed, rainfall, etc.) in a region; we can use the news API to obtain the title, content, author, release time, etc. of the news.

2. Accessing the API through PHP

Next we will introduce how to use PHP to access the API. First we need to know several common methods to obtain data: GET, POST, PUT, DELETE. Here we only introduce the GET method.

2.1 Using the file_get_contents function

PHP provides a file_get_contents function that can be used to obtain data from a remote server. We can use this function to access the API and get the returned data.

For example, we can access a JSON format API, the code is as follows:

In this example, we use the file_get_contents function to access a RESTful API (REpresentational State Transfer, representational state transfer) , this API can return a user's information, we are requesting the user information with id 1. The obtained data is a string in JSON format, and we use the echo function to output it to the page.

2.2 Using the cURL function

In addition to using the file_get_contents function, we can also use the cURL function to obtain data. cURL is a tool used to transfer files and data. It can transfer data through many protocols, including HTTP, FTP, SFTP, etc.

For example, we can use the cURL function to access a JSON format API, the code is as follows:

In this example, we use the curl_init function to initialize a cURL session, and use the curl_setopt function to set up cURL options. Set the CURLOPT_URL option to specify the requested URL, and set the CURLOPT_RETURNTRANSFER option to tell the cURL function to return the request result as a string. Finally, use the curl_exec function to execute the session, and use the curl_close function to close the session. The data obtained is the same as in the previous example.

3. Parse the returned data

The data we get is usually a string, and we need to parse it into an object or array in PHP to get the correct data. Usually the data we obtain has the following formats:

3.1 JSON format

JSON (JavaScript Object Notation) is a lightweight data exchange format that can be used by multiple programming languages support. It uses key-value pairs to represent data, including arrays, objects, strings, numbers, etc.

We can use the json_decode function provided by PHP to parse the JSON format string into an object or array in PHP. For example, we can use the following code to parse a JSON-formatted string into a PHP array:

In this example, we use the json_decode function to parse a JSON-formatted string into a PHP array, and Use the print_r function to output the array to the page. Note that the second parameter true means that an array is returned, not an object. If this parameter is not set, an object is returned by default.

3.2 XML format

XML (Extensible Markup Language) is a markup language that can be used to represent documents and data. It uses markup to describe the structure and semantics of data.

We can use the SimpleXML extension provided by PHP to parse XML format strings. For example, we can use the following code to parse an XML-formatted string into a PHP object:

    
        1
        Alice
    
    
        2
        Bob
    
';
$xml = simplexml_load_string($data);
print_r($xml);
?>

In this example, we use the simplexml_load_string function to parse an XML-formatted string into a PHP object, and Use the print_r function to output the object to the page.

4. Summary

Using PHP to access and parse API return data is a very common requirement. We often need to get data from a remote server and use it to update local applications. This article describes how to use PHP to access the API and parse the returned data. We introduced two methods of obtaining data: the file_get_contents function and the cURL function, and introduced two methods of parsing data formats: JSON format and XML format. These methods are very useful in actual development, and we can use them to access various open APIs to obtain more data and resources.

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