How to Use the OB (output buffer) function in PHP

From: http://bbs.phome.net/ShowThread? Threadid = 9247 & forumid = 2
In PHP programming, we often encounter some functions that directly generate output, such as passthru (), readfile (), and var_dump. however, sometimes we want to import the output of these functions to a file, or process the output of these functions as strings.
Now we need to use the output buffer function.

There are several main functions for processing the output buffer:
Ob_start () starts to output the buffer, and PHP stops the output. After that, the output is forwarded to an internal buffer.

The ob_get_contents () function returns the content of the internal buffer. This is equivalent to converting these outputs into strings.

Ob_get _ length () returns the length of the internal buffer.

Ob_end_flush () ends the output buffer and outputs the content in the buffer. After that, the output is normal.

Ob_end_clean () ends the output buffer and discards the content in the buffer.

For example, the var_dump () function outputs the structure and content of a variable, which is useful during debugging.
However, if the variable content contains special HTML characters such as <,>, the output will be invisible to the webpage. What should I do?
The output buffer function can easily solve this problem.

Ob_start ();
Var_dump ($ var );
$ Out = ob_get_contents ();
Ob_end_clean ();

At this time, the output of var_dump () already exists in $ out. You can output it now:

Echo '<PRE>'. htmlspecialchars ($ out). '</PRE> ';

Or wait for the future, or send this string to the template and then output it.