extraire des mots clés d'un texte

function motsCles($keywords, $txt){
$pattern = "#([".$keywords."]+)#i";

if(preg_match($pattern, $txt, $resultat)){
$rMotsCles ="";
for ($i=1; $i<count($resultat) && $i<10; $i++){
    $rMotsCles .= "<mot_cle_".$i.">".$resultat[$i]."</mot_cle_".$i.">";
}
return $rMotsCles ;
}
}

function motsCles($keywords, $txt){
$pattern = "#(".$keywords.")+?#imU";

if(preg_match_all($pattern, $txt, $resultat)){
$rMotsCles ="";
$lResultat = count($resultat[1]);//nombre de resultats
for ($i=0; $i < $lResultat && $i<10; $i++){
    $rMotsCles .= "<mot_cle_".($i+1)."><![CDATA[".$resultat[1][$i]."]]></mot_cle_".($i+1).">";
}
return $rMotsCles ;
}
}

<?php
function motsCle($kw, $t) {
    $aKw = explode('|',$kw);
    $aa = array();

    foreach ($aKw as $k=>$v) {
        if (false !== strposi($t, $v)) array_push($aa, '<mot_cle_'.($k+1).'><![CDATA['.$v.']]></mot_cle_'.($k+1).'>');
    }

    return implode($aa);
}
?>

<?php
function mots1($kw, $t) {
    $aKw = explode('|',$kw);
    $aTxt = str_word_count($t, 1);
    $aRes = array_intersect($aKw, $aTxt);
    array_walk($aRes, create_function('&$v,$k', '$v = "<mot_cle_".++$k."><![CDATA[".$v."]]></mot_cle_".$k.">";'));
    return implode($aRes);
}
?>