php“require”和“includes”方法是否每次都会占用内存/时间/性能？

Question

I have 30 html forms on a single page and I use ajax for 25 of those forms. All 30 of the forms can still be posted even if the user has javascript disabled since it will just use PHP and not ajax.

For example, my PHP code for the page looks something like this

if (!empty($_POST)) {
    require '/database-connect-file.php';
    require '/functions.php';
    $mysqli = connectToDatabase();
    require '/what-form-if-else-statements.php';
}

The functions.php page has 400 lines of code.

Will PHP have to process all 500 lines of code in the if statement that barely ever gets run since most users do have javascript enabled? Does PHP have to interpret the required files each and every time the page is loaded, even if there is empty post variable normally?

Answer 1

PHP will only execute the require directives and other lines of code in that block, if the expression in the if statement evaluates to TRUE.

As described in the section about expressions, expression is evaluated to its Boolean value. If expression evaluates to TRUE, PHP will execute statement, and if it evaluates to FALSE - it'll ignore it.

http://www.php.net/manual/en/control-structures.if.php

Although, !empty($_POST) may not work if you are using POST with AJAX and method="POST" on your forms. PHP will not know the difference between AJAX and a form submit if both are using the POST method.