Negate echo statement and convert to value? [duplicate]

This question already has answers here: Closed 10 years ago.

Possible Duplicate:

capturing echo into a variable

I have a function that echos a string. Is their any way (besides altering the function) that I can negate the echo statement?

example:

function echo_string(){
  echo "This is a string";
}

$dont_echo = negate_echo(echo_string());

$dont_echo .= ", 开发者_JS百科a negated string";

echo $dont_echo; // "This is a string, a negated string";

Is their anything like negate_echo?

---

ob_start();
echo_string();
$buffer = ob_get_clean();

That is: Starting a new output buffer, execute the function, get the buffers content and close it. See ob_get_clean^Docs.

---

The only way is to use output buffering:

ob_start();
echo_string();
$output = ob_get_clean();

echo $output.", a negated string";