PHP: Suppress output within a function?

Question

What is the simplest way to suppress any output a function might produce? Say I have this:

function testFunc() {
    echo 'Testing';
    return true;
}

And I want to call testFunc() and get its return value without "Testing" showing up in the page. Assuming this would be in the context of other code that does output other things, is there a good method for doing this? Maybe messing with the output buffer?

Answer 1

Here you go:

ob_start();
testFunc();
ob_end_clean();

"ob" stands for "output buffering", take a look at the manual pages here: http://www.php.net/outcontrol

Answer 2

Yes, messing with the Output Buffer is exactly the answer. Just turn it on before you call your method that would output (not the function itself, but where you call it, you could wrap it around your whole script or the script flow, but you can make it as "tight" as possible by just wrapping it around the call of the method):

function foo() {
  echo "Flush!";
  return true;
}

ob_start();
$a = foo();
ob_end_clean();

And no output is generated.

Answer 3

Isn't it as easy as applying some conditions to your code?

I mean if variable = testing then output, else don't?

For functions that have a result that outputs direct to the browser like EVAL, you could capture the result in an ob_start.

Answer 4

Yes you are on the right track as to leveraging PHP's output buffering functions, i.e. ob_start and ob_end_clean (look them up on php.net):

<?php

function testFunc() { echo 'Testing'; return true; }

ob_start();
$output = testFunc();
ob_end_clean();

echo $output;

?>

Answer 5

Hi I've got the opposite problem - I am not seeing the echo output from a function. Any idea what could cause this problem?

The output is a javascript alert as:

function alert()
{
    echo"<script>alert(\"Message\")</script>"; 
}

But no alert appears.