Trimming (computer programming)

In computer programming, trimming (trim) or stripping (strip) is a string manipulation in which leading and trailing whitespace is removed from a string.

For example, the string (enclosed by apostrophes)

would be changed, after trimming, to

Variants

Definition of whitespace

The characters which are considered whitespace varies between programming languages and implementations. For example, C traditionally only counts space, tab, line feed, and carriage return characters, while languages which support Unicode typically include all Unicode space characters. Some implementations also include ASCII control codes (non-printing characters) along with whitespace characters.

Java's trim method considers ASCII spaces and control codes as whitespace, contrasting with the Java isWhitespace() method, which recognizes all Unicode space characters.

Delphi's Trim function considers characters U+0000 (NULL) through U+0020 (SPACE) to be whitespace.

Usage

Following are examples of trimming a string using several programming languages. All of the implementations shown return a new string and do not alter the original variable.

Trim (computing)

A Trim command (known as TRIM in the ATA command set, and UNMAP in the SCSI command set) allows an operating system to inform a solid-state drive (SSD) which blocks of data are no longer considered in use and can be wiped internally.

Trim was introduced soon after SSDs were introduced. Because low-level operation of SSDs differs significantly from hard drives, the typical way in which operating systems handle operations like deletes and formats resulted in unanticipated progressive performance degradation of write operations on SSDs. Trimming enables the SSD to handle garbage collection overhead, which would otherwise significantly slow down future write operations to the involved blocks, in advance.

Although tools to "reset" some drives to a fresh state were already available before the introduction of trimming, they also delete all data on the drive, which makes them impractical to use for ongoing optimization. By 2014 many SSDs had internal idle/background garbage collection mechanisms that work independently of trimming; although this successfully maintains their performance even under operating systems that do not support Trim, it has the associated drawbacks of increased write amplification and wear of the flash cells.

Draft (hull)

The draft (American) or draught (British) of a ship's hull is the vertical distance between the waterline and the bottom of the hull (keel), with the thickness of the hull included; in the case of not being included the draft outline would be obtained. Draft determines the minimum depth of water a ship or boat can safely navigate. The draft can also be used to determine the weight of the cargo on board by calculating the total displacement of water and then using Archimedes' principle. A table made by the shipyard shows the water displacement for each draft. The density of the water (salt or fresh) and the content of the ship's bunkers has to be taken into account. The closely related term "trim" is defined as the difference between the forward and aft drafts.

Drafts of a ship

Keep

A keep (from the Middle English kype) is a type of fortified tower built within castles during the Middle Ages by European nobility. Scholars have debated the scope of the word keep, but usually consider it to refer to large towers in castles that were fortified residences, used as a refuge of last resort should the rest of the castle fall to an adversary. The first keeps were made of timber and formed a key part of the motte-and-bailey castles that emerged in Normandy and Anjou during the 10th century; the design spread to England as a result of the Norman invasion of 1066, and in turn spread into Wales during the second half of the 11th century and into Ireland in the 1170s. The Anglo-Normans and French rulers began to build stone keeps during the 10th and 11th centuries; these included Norman keeps, with a square or rectangular design, and circular shell keeps. Stone keeps carried considerable political as well as military importance and could take up to a decade to build.

Keep (surname)

Keep is a surname. Notable people with the surname include:

Arrakis

Arrakis (/əˈrækᵻs/;Arabic: الراقص‎, ar-rāqiṣ, "the dancer") — informally known as Dune and later called Rakis — is a fictional desert planet featured in the Dune series of novels by Frank Herbert. Herbert's first novel in the series, 1965's Dune, is popularly considered one of the greatest science fiction novels of all time, and it is sometimes cited as the best-selling science fiction novel in history.

In Dune, the planet is the home of the Fremen (Zensunni wanderers), and subsequently is the Imperial Capital of the Atreides Empire. Arrakis is the third planet orbiting the star Canopus, and it in turn is orbited by two moons, one of which has the image of the desert kangaroo mouse, Muad'Dib, on it; the other moon possesses the image of a human hand.

Environment and the spice

A desert planet with no natural precipitation, in Dune it is established that Arrakis had been "His Imperial Majesty's Desert Botanical Testing Station" before the discovery of melange, for which it is the only natural source in the universe. Melange (or, "the spice") is the most essential and valuable commodity in the universe, as it extends life and makes safe interstellar travel possible (among other uses). The planet has no surface water bodies, but open canals called qanats are used "for carrying irrigation water under controlled conditions" through the desert. The Fremen collect water in underground reservoirs to fulfill their dream of someday terraforming the planet, and pay the Spacing Guild exorbitant fees in melange to keep the skies over Arrakis free of any satellites which might observe their efforts. As indicated by its large salt flats, Arrakis once had lakes and oceans; Lady Jessica also notes in Dune that wells drilled in the sinks and basins initially produce a "trickle" of water which soon stops, as if "something plugs it."