Com str.php

merge_space

$result = preg_replace( "/\s+/", " ", $str);

function merge_space($str) { return preg_replace( "/\s+/", " ", $str); }

function merge_space($str) {
	$repeat = true;
	while($repeat) {
		$temp = $str;
		$str = str_replace('  ', ' ', $str);
		if($temp == $str) $repeat = false;
	}
	return $str;
}