Detailed explanation of how to use php include

include statement includes and runs the specified file.

The following documents also apply to require.

Included filesFirst search according to the path given by the parameter. If no directory (only file name) is given, search according to the directory specified by include_path. If the file is not found under include_path, include will finally search in the directory where the calling script file is located and the current working directory. The include structure will issue a warning if the file is not found at the end; this is different from require, which will issue a fatal error.

If a path is defined - whether it is an absolute path (starting with a drive letter or \ under Windows, and / under Unix/Linux) or a relative path to the current directory (starting with . or ..) --include_path will be completely ignored. For example, if a file begins with ../, the parser will look for the file in the parent directory of the current directory.

For more information on how PHP handles include files and include paths, see the documentation in the include_path section.

When a file is included, the code contained in it inherits the

variable scope of the line where the include is located. From that point on, any variables available in the calling file at that line are also available in the called file. However, all functions and classes defined in include files have global scope.

php include function should be our most commonly used method. The include() statement includes and runs the specified file. But just because of this, we may have overlooked some of its other uses. I read it again because of work needs, and will make a brief record here:

1. The simple difference between include and require

When the file included in include does not exist, it only generates a warning, but the script will continue to execute.

If the file referenced by require does not exist, an error will be prompted and the script will be terminated.

2. Variable scope of variables in the included file

When a file is included, the code contained in it inherits the variable scope of the line where include is located. If include appears within a function in a calling file, all code contained in the called file will behave as if it were defined inside that function. However, all functions and classes defined in include files have global scope.

When a file is included, the parser leaves PHP mode and enters HTML mode at the beginning of the target file, and resumes at the end of the file. For this reason, any code in an object file that should be executed as PHP code must be included within valid PHP start and end tags.

3.include() return value

If you obtain the variable value in include, you need to add return

For example: file return.php

<?php
  $var=&#39;ok&#39;;
  return $var;
?>

if( include('return.php')=='ok' ) { ... } if does not execute the inside because the include('return.php') value is 1

if( (include 'return.php')=='ok' ) { ... } if can execute the

inside, so if you use include for conditional comparison, you need to do this (include 'return.php')

4. Use output buffering to include the PHP file into a

string

<?php
$string = get_include_contents(&#39;somefile.php&#39;);
function get_include_contents($filename) {
    if (is_file($filename)) {
        ob_start();
        include $filename;
        $contents = ob_get_contents();
        ob_end_clean();
        return $contents;
    }
    return false;
}
?>

1. Include some class definition files, function files, This is commonly used;

2. Contain HTML files

include "header.htm";

The header.htm above can be integrated with PHP statements.

Because htm static files can be included, a caching mechanism can be designed. For example, some pages can be divided into several parts. Some parts that are inefficient in reading the database can be cached as HTML and then introduced through include.

3.include files can have returns;

$i = include 'abc.php';

abc.php source code example:

<?php
return "hello world";
?>

Then echo $i; will output hello world.

If abc.php does not return, then echo $i will output the variable range of 1

include

$a="hello world";
include "abc.php";

$a is visible in abc.php;

The variables in abc.php are also visible after include; the usage is very flexible!

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