Delete repeated string from string?

Hi,

Is there a function to remove repetitions of a string within another string?
I know strpos() can be used to test if there is a match, and substr_count can be used to count the number of repetitions, but I cant find anything to delete the repetitions.

For example:

$haystack = "hello world, 123, hello world";

should read:

hello world, 123

function remove_repeats( $string, $needle )
{
if ( FALSE !== strpos( $string, $needle ) )
{
$string = explode( $needle, $string );
$string = array_shift( $string ) . $needle . implode( '', $string );
}
return $string;
}



$string = 'hello world, 123, hello world, 456, hello world, 789, hello world';

echo remove_repeats( $string, 'hello world' ); // hello world, 123, , 456, , 789,

As you can see from the return value, additional processing will need to take place.

Thanks ever so much. That's perfect!