Subjects - Internet and Businesses Online

In Linux and Unix, the syntax that is commonly used by many applications for specifying text patterns is known as regular expressions or in short form - regex. Regex is a very powerful technique to describe patterns and many programs use them to describe sequences of characters to be matched. Search programs suc

According to USFDA, a combination product is one composed of any combination of a drug and device; biological product and device; drug and biological product

h as 'grep' rely heavily on regex. Basically regex forms the core in the linux world. Many scripting languages such as perl, ruby, php...etc has build in regex functions as well. So you can see, learning regular expression is important because they are used alot in many places and probably more so in the future.

; or drug, device, and biological product and fixed dose combination would include two or more combinations of drug.

Examples of combination products may in

Regex can be scary at first but if you can get the basics, it is really not too hard to understand. In this article, we are going to look at how regex comes into the picture when writing php applications.

To do a quick summary so far, a regular expression is a sequence of literal characters, wildcards, modifie

lude drug-coated devices, drugs packaged with delivery devices in medical kits, and drugs and devices packaged separately but intended to be used together.

s and anchors.

Literal Characters

Literal characters are letters, digits and special characters that match only themselves. Examples are abc, 123, ~@ and so on (some characters are reserved though).

- An inclusion range [m-n] matches one of any character included in the range from m to n.

Example '[a-

here is enormous increase in the number of combination products entering the market in the recent years. Combination products have proven advantages but fixe

]' will match any alpha character that falls within the a to z range.

- An exclusion range [^m-n] matches one of any character not included in the range from m to n. Example '[^0-9]' will match any non-digit character.

- A period "." matches any character. It is also known as the wildcard. Example 'a.c' will m

d dose combinations are still in the process of convincing regulatory authority on their advantages over the single ingredient formulations.

Combination pro

tch 'aec', 'acc', 'a@a' and so on.

- The escape character '' enable interpretation of special characters. Example 'a.c' will match 'ac' only. Remember that '.' is a reserved character to represent a wildcard? Therefore to match a period, ie '.', we need to escape it like so '.'

- The expression [:alnum:] will

ucts have become life saving products for the pharmaceutical companies who doesn’t have many innovative molecules in their product pipeline and have been inc

match all alpha-numeric characters. It is a shortcut to [A-Za-z0-9]. As you can see, it is not really a shortcut. The expression [:alnum:] might be easier to remember for some people.

- The expression [:alpha:] will match all alpha characters. It is a shortcut to [A-Za-z].

- The expression [:blank:] will match

easingly used in the product life cycle management. Even the companies having product patents are trying to extend their product life cycle through the combi

a space or tab.

- The expression [:digit:] will match a numeric digit. It is a shortcut to [0-9].

- The expression [:lower:] will match all lowercase letters. It is a shortcut to [a-z].

- The expression [:upper:] will match all uppercase letters. It is a shortcut to [A-Z].

- The expression [:punct:] will mat

nation products and maximize the revenues. But the companies involved in this practice are overlooking that they are burdening the patients both economically

h all printable characters, excluding spaces and alphanumerics.

- The expression [:space:] will match a whitespace character.

Modifiers

A modifier alters the meaning of the immediately preceding pattern character.

- An asterisk ('*') matches 0 or more of the preceding term. Example 'a*' will match '',

and physically. They need to rightly judge the benefits of the combination products and they have to even look at the risks involved when combining the produ

'a', 'aa', 'aaaaa' and so on (Note the use of ''. It simply means that the expression matches nothing as well).

- A question mark ('?') matches 0 or 1 of the preceding term. Example 'a?' will match '' and 'a' only.

- A plus sign ('+') matches 1 or more of the preceding term. Example 'a+' will match 'a', 'aaaaa

ts. Some of the combination products were well accepted by physicians while others suffered. Companies involved in development of combination products are fi

a' and so on. It will not match ''.

- {m,n} matches between m and n occurences of the preceding term. Example 'a{1,3}' will match 'a', 'aa' and 'aaa' only.

- {n} matches exactly n occurences of the preceding term. Example 'a{2}' will match 'aa' only.

Anchors

Anchors establish the context for the patte

ding difficulty in defining their combination products and facing various challenges from selecting a combination to marketing it.

Following aspects would a

rn such as "the beginning of a word" or "end of word".

- The pike '^' marks the beginning of a line. Example '^http' will match any new line that starts with 'http'.

- The dollar sign '$' marks the end of a line. Example 'after$' will match any line that ends with 'after'. (Variables in php starts with $. Try

dd to the challenges in developing combination products:

Which markets to tap where the combination products can do fairly well?
Which combination prod

ot to confuse with it).

Grouping

Grouping '( )' allows modifiers to apply to groups of regex specifiers instead of only the immediately proceding specifier. Example '( aa | bb )' will match either 'aa' or 'bb'

Enough of boring stuff, it is time to put what the theory of regex into good use.

PHP Imp

cts are meaningful and rational?
Which therapeutic categories to select?
Which Combinations can address unmet needs of the patients?
Do combin

ementation

There are 2 main variants of regex, Perl-compatible regex (PCRE) and POSIX-Extended. PHP offers quite alot of functions to implement these 2 types of regex. In PHP, the most commonly used PCRE function is 'preg_match' and in POSIX-extended regex, 'ereg'. Both syntax are slightly different but eq

tions increase the patient compliance?
What would be the developing cost?
How to tackle the risks encountered during combination product developmen

ally powerful. The preference to use 'preg_match' or 'ereg' is entirely up to individual although Zend suggested that preg_match is slightly faster. I prefer to use 'eregi' simply because of my background in linux administration.

Example 1: Matching United States 5 or 9 digit zip codes

Zip codes in USA

t?

As combination products don't fit into the traditional categories of drugs, medical devices, or biological products, the USFDA is in the process of devel

ave the following format ##### or #####-#### where # is a digit. If you want to verify the zip code submitted say from an online form, you will need to use regex somewhere in your script to verify it. The matching POSIX-extended regex pattern will be:

[[:digit:]]{5}(-[[:digit:]]{4})?

Confused? Wait, let me exp

ping new procedures for reviewing their safety, efficacy and quality.

Professional from academic institutions, pharmaceutical industries, health care indust

lain why. This regex is split up into 2 parts: [[:digit:]]{5} and (-[[:digit:]]{4})?.

First Part: '[[:digit:]]' means the digit range and {5} means that the digit must occur 5 times.

Second Part: The bracket '( )' groups the '-[[:digit:]]{4}' together and the '?' means the expression '(-[[:digit:]]{4})' can ei

y and representatives from various regulatory agencies are working out to design the regulatory requirements for manufacture and sale of combination products

her occur 0 or 1 time.

To implement the regex in PHP, we use the following code:

$zipCodes = 'xxxxx-xxxx';

$pattern = '[[:digit:]]{5}(-[[:digit:]]{4})?';

if (ereg($pattern,$zipCodes)) {

echo "matched found ";

}

else {

echo "match not found";

}

Example 2: Matching Dates

Say we want to verify th

.

As there is an increasing trend of the combination products companies manufacturing such products should be able to tackle the problems involved in the de

dates entered by the user. If we only accept dates like "YYYY-MM-DD" or "YYYY-M-D", the regex pattern will be

[0-9]{4}(-[0-9]{1,2})+

The '+' behind the term (-[0-9]{1,2}) means that the term must occur at least once. Note that I can also rewrite the regex as:

[[:digit:]]{4}(-[[:digit:]]{1,2})+

or

[0-9]{4}-

elopment. They need to be wiser in analyzing the market trends and the regulatory requirements.

Companies that provide selfless information through particip

0-9]{1,2}-[0-9]{1,2}

As you can see, there can be many solutions to a problem...

Conclusion

Regex may be hard to digest at first but the logic is simple if you are able to practice more. Learning regex is as important as learning PHP. More examples can be seen at web-developer.sitecritic.net. Good luck

tion in industry events and feedback to regulatory authorities would be able to face the challenges and will be successful in developing combination products

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