php preg_match_all正则匹配纯字母

$pattern = '/[a-zA-Z]+/';//匹配至少一个字母并只有字母的字符串

$a = '<a href="/abc.html"><a href="/baidu.html">';
$pattern = '/<a href=\"\/([a-zA-Z]+).html\">/';
preg_match_all($pattern,$a,$matches);
foreach($matches[1] as $key=>$value){
echo $value,"<br/>";
}

结果输出
abc
baidu