Comparison between include() and require() in php_PHP Tutorial

There is no big difference in performance between PHP's require() and include().

The only differences are:

The file must be read and evaluated every time when include() is executed;
The file is only processed once when require() is executed (actually , the file content replaces the require() statement).
That is, if there is code that contains one of these instructions and code that may be executed multiple times, it is more efficient to use require().

In addition, if you need to read a different file each time you execute the code, or have a loop that iterates through a set of files, you should use include(), because you can set a Variable, this variable is used when the parameter is include().

Although the require() performance of PHP is similar to include(), through my own study and search, I still found the following 6 differences.

1.
The difference is that for include(), the file must be read and evaluated every time when include() is executed;
And for require() ), the file is processed only once (in fact, the file content replaces the require() statement).
This means that if you have code that contains one of these instructions and code that may be executed multiple times, it is more efficient to use require().

2.
require is only executed once, no, that is inappropriate. It should be said that require replaces the contents of the specified file first and then runs it, so it does not know whether you have set up a FOR loop. As for the include statement,

means when it is executed, it substitutes the contents of the specified file and continues execution.
So, if you want to read a different file each time you execute the code, or have a loop that iterates through a set of files, use include(), because you can set a variable for the file name you want to include as a parameter Use this variable when including()

.

3. When
include is executed, if an error occurs in the file included, it will not stop immediately; while require will terminate the program immediately and no longer execute.

4. Include can be used in loops; require cannot.

5. include has a return value, but require does not (maybe because require is faster than include)

The code in ok.php is echo "ok!";

$login = include('ok.php');
if(!empty($login)){ echo "File included successfully";
}else{ echo "File included failed"; }

The final return result is: ok! File inclusion successful

As long as there is a statement in ok.php, success will be returned.

Give an example:

The code in 1.php is as follows:
return array(
'ILOVEYOU'=>1,2 ,3,4
);
?>

The code in index.php is as follows:
$a = array_change_key_case(include '1.php' );

print_r($a);
?>

The result of accessing index.php is as follows:
Array ( [iloveyou] => 1 [0] = > 2 [1] => 3 [2] => 4 )

6. How to use require: This function is usually placed at the front of the PHP program. Before the PHP program is executed, it will First read in the file specified by require and make it become part of the PHP program web page. Frequently used functions

can also be introduced into web pages in this way.
Include usage: This function is generally placed in the processing part of process control. The PHP program webpage only reads the include file when it reads it. In this way, the process of program execution can be simplified