<?php
function replaceSpace($metin)
{
$metin = preg_replace("/s+/", " ", $metin);
$metin = trim($metin);
return $metin;
}

$kelime2=replaceSpace($metin);

if ($kelime2==1){
$sonuc = xx;
}else{
$sonuc= yy;
}

echo $sonuc;
?>

$kelimeler = array("kelime1+kelime2", "kelime3-kelime4", "kelime5", "kelime6+kelime7-kelime8");
$yeni = array();
foreach($kelimeler as $kelime){
   if($kelime != ''){
      if(strstr($kelime, '+')){
         $bolumle = explode('+', $kelime);
         $yeni[] = $bolumle[0];
      }
      elseif(strstr($kelime, '-')){
         $bolumle = explode('-', $kelime);
         $yeni[] = $bolumle[0];
      }
      else{
         $yeni[] = $kelime;
      }
   }
}
echo '<pre>';
print_r($yeni);
echo '</pre>';