![]() ![]() Note that for every file inclusion function previously listed, the file to load can be a string constant or a variable containing the name of the file. The general syntax of both the include and require statements are as follows: Because it is unacceptable to define the same function multiple times within a script, these functions allow the developer to include a script as needed without having to check whether it has been previously loaded. ![]() If an attempt is made to load a file twice using one of these two methods, it will be ignored. When the include_once/ require_once statements are used, the file cannot be loaded or executed multiple times. The only difference between the include/ require and include_once/ require_once statements is how many times a given file will actually be loaded. First, let's discuss how each of the two flavors work. As you may suspect, of these four statements only the include and require statements actually differ with any great significance, and it is those differences that I'll focus on. Regardless of the reasons, inclusion of external files is accomplished through the include, include_once, require, and require_once PHP statements. Furthermore, by storing sensitive static information such as database login information in separate files, they can be safely placed outside the Web tree of the server and thus be inaccessible by the public. ![]() In PHP, this organization is accomplished by separating your scripts into multiple files and including them when appropriate. In this respect, and as you accumulate an ever-growing library of functions, the need to organize them becomes more and more paramount. In this case, the Logger.php file is used twice, once in the Database.php file and another in the is always good practice to make your scripts as modular as possible, designing your functions in such a way that they can be used in other PHP scripts. The Database.php file also loads the Logger.php file. Image that you have a file called index.php that loads two other files: In the example above, if you use the include_once construct, the script will work properly: PHP include_once Demo Code language: HTML, XML ( xml ) Why use the PHP include_once construct Simply put, the include_once loads the file just once regardless of how many times the file is included. The include_once behaves like the include statement except that if the file is included again, the include_once won’t load the file and returns true. To avoid including a file more than once, you can use the include_once statement: include_once 'path_to_file' Code language: PHP ( php ) In the index.php file, if you include the header.php file twice, you’ll see that the page will have two headers: PHP include_once Demo Code language: HTML, XML ( xml ) The functions.php has the dd() function definition: ' Īnd in the index.php file, you include the functions.php file twice: PHP include_once Code language: HTML, XML ( xml )įooter.php Code language: HTML, XML ( xml ) └── index.php Code language: plaintext ( plaintext ) Suppose that you have the following project directory. If the included file has a function, you’ll get a fatal error because the function is already redeclared in the first load. Sometimes, you may have a file that is included more than once. In the include tutorial, you learned how to load the code from another file using the include construct. Introduction to the PHP include_once construct Summary: in this tutorial, you will learn how to use the PHP include_once construct to include a file once. ![]()
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