PHP nested output Buffer Code instance _php

The output cache of PHP can be nested. The nesting level can be output with ob_get_level ().
The test found a different output in the CLI and the browser (PHP5.4).

The manual is described below:

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

It's also easy to get the right output:

The code is as follows:

Ob_end_clean ();
Echo Ob_get_level (); 0

Back to the chase:

The code is as follows:

Ob_end_clean ();

Ob_start ();
Echo ' PHP1 ';//This is not output in the page
$a = Ob_get_level ();
$b = Ob_get_contents ();//Get cached results, assign variables
Ob_clean ();

Ob_start ();
Echo ' PHP2 ';//This is not output in the page
$c = Ob_get_level ();
$d = Ob_get_contents ();//Get cached results, assign variables
Ob_clean ();

Ob_start ();
Echo ' php3 ';//This is not output in the page
$e = Ob_get_level ();
$f = Ob_get_contents ();//Get cached results, assign variables
Ob_clean ();

echo ' Level: '. $a. ', ouput: '. $b. '
';
echo ' Level: '. $c. ', ouput: '. $d. '
';
echo ' Level: '. $e. ', ouput: '. $f. '
';

The results are as follows:

The code is as follows:

Level:1,ouput:php1
Level:2,ouput:php2
Level:3,ouput:php3

Of course, when you turn off a level of buffering, the following tests:

The 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 (); Empty the cache and close the cache

Ob_start ();
Echo ' php3 ';
$e = Ob_get_level ();
$f = Ob_get_contents ();
Ob_clean ();

echo ' Level: '. $a. ', ouput: '. $b. '
';
echo ' Level: '. $c. ', ouput: '. $d. '
';
echo ' Level: '. $e. ', ouput: '. $f. '
';

The results are as follows:

The code is as follows:

Level:1,ouput:php1
Level:2,ouput:php2
Level:2,ouput:php3

