PHP nested output buffer code instance and php nested code instance

PHP nested output buffer code instance and php nested code instance

PHP output cache can be nested. You can use ob_get_level () to output the nested level.
The test results are different in cli and browser (PHP5.4 ).

The manual description is as follows:

Ob_get_level () will always return 0 inside a destructor.
This happens because the garbage collection for output buffers has already done before the destructor is called

It is easy to output the correct output:
Copy codeThe Code is as follows:
Ob_end_clean ();
Echo ob_get_level (); // 0

Back to the topic:
Copy codeThe Code is as follows:
Ob_end_clean ();
 
Ob_start ();
Echo 'php1'; // It is not output on the page
$ A = ob_get_level ();
$ B = ob_get_contents (); // obtain the cache result and assign the variable
Ob_clean ();
 
Ob_start ();
Echo 'php2'; // This is not output on the page
$ C = ob_get_level ();
$ D = ob_get_contents (); // obtain the cache result and assign the variable
Ob_clean ();
 
Ob_start ();
Echo 'php3'; // This is not output on the page
$ E = ob_get_level ();
$ F = ob_get_contents (); // obtain the cache result and assign the variable
Ob_clean ();
 
Echo 'level: '. $ a.', ouput: '. $ B.' <br> ';
Echo 'level: '. $ c.', ouput: '. $ d.' <br> ';
Echo 'level: '. $ e.', ouput: '. $ f.' <br> ';

The result is as follows:
Copy codeThe Code is as follows:
Level: 1, ouput: php1
Level: 2, ouput: php2
Level: 3, ouput: php3

Of course, when you disable a buffer level, perform the following test:
Copy codeThe Code is as follows:
Ob_end_clean ();
 
Ob_start ();
Echo 'php1 ';
$ A = ob_get_level ();
$ B = ob_get_contents ();
Ob_clean ();
 
Ob_start ();
Echo 'php2 ';
$ C = ob_get_level ();
$ D = ob_get_contents ();
Ob_end_clean (); // clears the cache and closes the cache.
 
Ob_start ();
Echo 'php3 ';
$ E = ob_get_level ();
$ F = ob_get_contents ();
Ob_clean ();
 
Echo 'level: '. $ a.', ouput: '. $ B.' <br> ';
Echo 'level: '. $ c.', ouput: '. $ d.' <br> ';
Echo 'level: '. $ e.', ouput: '. $ f.' <br> ';

The result is as follows:
Copy codeThe Code is as follows:
Level: 1, ouput: php1
Level: 2, ouput: php2
Level: 2, ouput: php3