How to clear previously echoed items in PHP

Question

In php, is there any way to clear/remove all previously echoed or printed items?

For example:

<?php  echo 'a'; print 'b';  // some statement that removes all printed/echoed items  echo 'c';  // the final output should be equal to 'c', not 'abc'  ?> 

My script uses the include function. The included files are not supposed to echo anything. Just in case someone (ex = hacker) tries, I need a way to remove.

Answer 1

<?php  ob_start(); echo 'a'; print 'b';  // some statement that removes all printed/echoed items ob_end_clean();  echo 'c';  // the final output is equal to 'c', not 'abc'  ?> 

Output buffering functions

The output buffering functions are also useful in hackery to coerce functions that only print to return strings, ie.

<?php ob_start(); var_dump($myVar); $data = ob_get_clean(); // do whatever with $data ?>