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Regular expressions (or regex) are a common and very versatile programming technique for manipulating strings. On Wikipedia you can use a limited version of regex called a Lua pattern to select and modify bits of text from a string. The pattern is a piece of code describing what you are looking for in the string.
String functions are used in computer programming languages to manipulate a string or query information about a string (some do both).. Most programming languages that have a string datatype will have some string functions although there may be other low-level ways within each language to handle strings directly.
The array L stores the length of the longest common suffix of the prefixes S[1..i] and T[1..j] which end at position i and j, respectively. The variable z is used to hold the length of the longest common substring found so far. The set ret is used to hold the set of strings which are of length z.
COBOL uses the STRING statement to concatenate string variables. MATLAB and Octave use the syntax "[x y]" to concatenate x and y. Visual Basic and Visual Basic .NET can also use the "+" sign but at the risk of ambiguity if a string representing a number and a number are together. Microsoft Excel allows both "&" and the function "=CONCATENATE(X,Y)".
In computer science, string interning is a method of storing only one copy of each distinct string value, which must be immutable. [1] Interning strings makes some string processing tasks more time-efficient or space-efficient at the cost of requiring more time when the string is created or interned.
The string-search functions in Lua script can run extremely fast, comparing millions of characters per second. For example, a search of a 40,000-character article text, for 99 separate words (passed as 99 parameters in a template), ran within one second of Lua CPU clock time.
Lua patterns are loosely based on regular expressions (sometimes shortened to regex or regexp). Lua patterns deliberately lack the most complex regular expression constructs (to avoid bloating the Lua code base), where many other computer languages or libraries use a more complete set.
This essay explains various issues about the execution speed and performance of Lua script in Wikipedia. The speed of using Lua modules can vary greatly, compared to similar markup-based templates, often ranging from 4x-8x times faster, or 180,000x faster when scanning text strings, which can exceed the 500-character parser-function markup limit as 64,000 characters or more.