Does PHP internally merge all required files into one script or only include the necessary files based on conditions?

When using the `require` or `include` functions in PHP to include files, all required files are merged into the main script at the point where the `require` or `include` statement is used. This means that all included files are processed and executed regardless of any conditions. To include files based on conditions, you can use conditional statements to control when to include specific files. 

if ($condition) {
    require 'file1.php';
} else {
    require 'file2.php';
}

Keywords

PHP file inclusion conditional includes script merging performance optimization

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