Getting CAPS from a string into a variable

I want to grab just the capital letters from a string into a variable.

The string would be like "Signs--Awards Freestanding"
I want the capital letters only, "SAF" in this case, in a variable.

Do I need to use a regexp or will str_replace do it?

Thank you for any help you might provide and thank you for you time and efforts.

Use a regular expression:

$string = "Silly Rabbit, Tricks are for Kids!";
preg_match_all("/[A-Z]/", $string, $out_array);
print_r($out_array);

All caps should now be in your $out_array.

--Brad Fears

First, thank you for your response. It seems to be what I need but...

print_r($out_array);

Produces this:

Array ( [0] => Array ( [0] => S [1] => A [2] => F ) )

Whereas, I need all the values in one variable:

$pn_prefix == "SAF"

I tried to figure this out myself and hoped implode() would do the trick but both

$pn_prefix = implode('', $out_array);

and

$pn_prefix = implode("", $out_array);

(single quotes and double quotes in the "string glue")

give the error

"Warning: Array to string conversion..." (which I can't find any useful help about).

So I'm stuck again. Hope you can help.

Thank you.

Here's how I do it:

$a='ABC123abc';
print ereg_replace("[^{A-Z]","",$a);}

There, that was easy.

Ah! Ooooo! Thank you!!!

I'm sure I'll find more uses for this!