Professional Information Technology-Programming Book part 119 docx
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<! Body >
<BODY>
<!-{2,}.*?-{2,}>
<! Start of page >
<HTML>
<! Start of head >
<HEAD>
<TITLE>My Title</TITLE> <! Page title >
</HEAD>
<! Body >
<BODY>
<!-{2,} matches the start of the comment, <! followed by two or more hyphens. .*?
matches the comment body (not greedy). -{2,}> matches the end of the comment.
Note
This regular expression matches two or more hyphens and can
thus be used to find CFML comments, too (which are identified by
three hyphens). However, the pattern does not attempt to match
the number of hyphens at the comment's start and close
(potentially a useful enhancement in finding mismatched
comments).
JavaScript Comments
Comments in JavaScript (and in other scripting languages, including ActionScript
and other ECMA Script derivatives) are preceded by //. As in the previous
example, being able to locate all comments in a page at once can be very useful.
<SCRIPT LANGUAGE="JavaScript">
// Turn off fields used only by replace
function hideReplaceFields() {
document.getElementById('RegExReplace').disabled=true;
document.getElementById('replaceheader').disabled=true;
}
// Turn on fields used only by replace
function showReplaceFields() {
document.getElementById('RegExReplace').disabled=false;
document.getElementById('replaceheader').disabled=false;
}
//.*
<SCRIPT LANGUAGE="JavaScript">
// Turn off fields used only by replace
function hideReplaceFields() {
document.getElementById('RegExReplace').disabled=true;
document.getElementById('replaceheader').disabled=true;
}
// Turn on fields used only by replace
function showReplaceFields() {
document.getElementById('RegExReplace').disabled=false;
document.getElementById('replaceheader').disabled=false;
}
This is a simple one; //.* matches // followed by the comment body.
Note
Unlike most regular expression implementations, in ColdFusion .
matches new-line characters. As
such, if you are using ColdFusion
you will need to modify this pattern so that it uses a lazy quantifier
(replacing .* with .*?).
Credit Card Numbers
Credit card numbers cannot be truly validated using regular expressions; final
validation always requires some interaction with a credit card processing
organization. However, regular expression validation can indeed be useful in
trapping typos (like one digit too many or too few) before submitting any data
anywhere.
Note
The patterns used here all assume that any embedded spaces or
hyphens have been removed. This is generally a good practice to
remove any nondigits from credit card numbers before performing
any regular expression processing.
All credit cards follow a basic numbering scheme—an opening digit sequence
followed by a specified number of digits. We'll start with MasterCard.
MasterCard: 5212345678901234
Visa 1: 4123456789012
Visa 2: 4123456789012345
Amex: 371234567890123
Discover: 601112345678901234
Diners Club: 38812345678901
5[1-5]\d{14}
MasterCard: 5212345678901234
Visa 1: 4123456789012
Visa 2: 4123456789012345
Amex: 371234567890123
Discover: 601112345678901234
Diners Club: 38812345678901
All MasterCard numbers are 16 digits; the first digit is always 5, and the second
digit is 1 through 5. 5[1-5] matches the first two digits; \d{14} matches the next 14
digits.
Visa is a little trickier.
MasterCard: 5212345678901234
Visa 1: 4123456789012
Visa 2: 4123456789012345
Amex: 371234567890123
Discover: 601112345678901234
Diners Club: 38812345678901
4\d{12}(\d{3})?
MasterCard: 5212345678901234
Visa 1: 4123456789012
Visa 2: 4123456789012345
Amex: 371234567890123
Discover: 601112345678901234
Diners Club: 38812345678901
