preg_quote

preg_quote  转义正则表达式字符（向正则表达式语法中的字符前增加一个反斜线）（如下的例子中则是将*very*变成\*very\*）,返回转义后的字符串。

$textbody = "This book is *very* difficult to find.";
$word = "*very*";

$textbody = preg_replace ("/" . preg_quote($word, '/') . "/", "<i>" . $word . "</i>", $textbody);
dd($textbody);