Dear monks,

I've regex below that's used to catch an input (a sentence) that contains illegal characters. I'm puzzled why I needed to escape the $ sign to make a digit "0" not matched i.e. with $ unescaped, a string such as "hello there0" is matched (so not okay), with $ escaped, the same string is not matched (so okay) 

if ($input =~ /[<>@#\$%^&*()_+=|\{\}\[\]\/\\]/) {
    print "not okay";
}
else {
    print "okay";
}

[download]

Please enlighten me and many thanks in advance.

In reply to Regex help by Anonymous Monk

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