The easiest way is not to try to look for all the weird characters, but instead to look for only the permitted characters and invert the test. If, for example, you only permit letters, numbers and commas, you would do something like ...

if($text !~ /^[a-z0-9,]*$/i) {
    die "bad characters\n";
}
[download]

Doing it this way ensures that you only permit what you want. This is good practice, because you won't accidentally let bad stuff through. If you try to think of all the weird characters that someone can type you're *bound* to forget some of them. For example, you're probably thinking of banning é, è, ñ and ç. But had you remembered æ, œ, ß, ð, ø, å, ł and þ?

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.