Very good post to understand basic regex Expressations

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http://net.tutsplus.com/tutorials/other/8-regular-expressions-you-should-know/



Here is a wonderful post to understand how regex can be used for most basic matches and valiadations in general.

This can help better understanding for making more complex use


In computing, regular expressions provide a concise and flexible means for identifying strings of text of interest, such as particular characters, words, or patterns of characters.


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