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Regular Expression Tutorial
Before we look at formal definitions of regular expressions, it is helpful to know that the concept of "strings" is important in defining regular expressions. A "string" is merely as sequence of text characters put together. Imagine a bunch of beads which each have a letter of the alphabet on them. If you put these beads on a physical string, they now have an order and, perhaps, greater meaning. So when the word "string" is used, it is simply an ordered collection of characters. "This" is a string and "that" is another string. "This entire sentence is a string."
"CHRIS" is a string.
Now that we know what a string is, what is the definition of regular expressions? Here's a good official sounding definition from Wikipedia:
Technically, a generalized interpretation of the term "regular expression" could apply to other functions besides the text string processing system. An example would be the very structured and regular syntax used to describe things like programming languages in reference manuals. In this application and others, there is a lot more variability in the specific syntax among various applications. Since pattern matching regular expressions have become somewhat standardized, they are what the term "regular expression" most always refers to.
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|Chris X. Edwards ~ December 2003|