CamelCase Totally Explained

Everything about Camelhumpedword totally explained

CamelCase (also spelled camel case) and sometimes known as camel caps or medial capitals is the practice of writing compound words or phrases in which the words are joined without spaces and are capitalized within the compound — as in Patti LaBelle, "BackColor" or "iMac". The name comes from the uppercase "bumps" in the middle of the compound word, suggestive of the humps of a camel.
CamelCase is a standard identifier naming convention for several programming languages, and has become fashionable in marketing for names of products and companies. However, CamelCase is rarely used in formal written English, and most style guides recommend against its use.

Variations and synonyms

For clarity, this article will call the two varieties UpperCamelCase and lowerCamelCase. Some people and organizations use the term camelCase only for lowerCamelCase, and refer to UpperCamelCase as PascalCase. In some contexts, however, the term CamelCase doesn't discriminate between the two. Other synonyms include:

BumpyCaps

BumpyCase

CamelCaps

CamelHumpedWord

CapWords in Python

CoolCaps

mixedCase (for lowerCamelCase) in Python In title case, three word types are not capitalized unless they're the first or last word in the title or headline: 1. conjunctions such as and and but, 2. prepositions such as by, with, to, and through, and 3. nonpossessive articles such as a, an, and the.

History

Early uses

CamelCase has been sporadically used in English since ancient times, for example as a traditional spelling style for certain surnames, such as in Scottish MacLean (originally, "son of Gilian") and Hiberno-Norman FitzGerald ("son of Gerald"). This same convention is sometimes used in English for surnames of foreign origin which include prepositions or other particles, for example, DuPont (from French Dupont or du Pont), DiCaprio (from Italian Di Caprio), and VanDyke (from Dutch van Dijk). The actress ZaSu Pitts, whose fame peaked in the 1930s and 1940s, sometimes spelled her given name in CamelCase, emphasizing its derivation from two other names.
From the mid-20th century, it has occasionally been used for corporate names and product trademarks, such as

CinemaScope and VistaVision, rival widescreen movie formats (1953)

ShopKo (1962)

MisteRogers, the Canadian version of Mister Rogers' Neighborhood (1962)

AstroTurf (1967)

ConAgra, formerly Consolidated Mills (1971). CamelCase has also been used for acronyms like DoD, chemical formulas like NaCl (early 19th century), and other technical codes like HeLa (1983).

Origins of use in computing

The use of CamelCase became widespread only in the 1970s and 1980s, when it was adopted as a standard or alternative naming convention for multi-word identifiers in several programming languages. The origin of this convention hasn't yet been settled.

Background: multi-word identifiers

Computer programmers often feel the need to write descriptive (hence multi-word) identifiers, like "previous balance" or "end of file", in order to improve the readability of their code. However, most popular programming languages forbid the use of spaces inside identifiers, since they're interpreted as delimiters between tokens. The alternative of writing the words together as in "endoffile" isn't satisfactory, since the word boundaries may be quite difficult to discern in the result.
Some early programming languages, notably Lisp (1958) and COBOL (1959), addressed this problem by allowing a hyphen ("-") to be used between words of compound identifiers, as in "END-OF-FILE". However, this solution wasn't adequate for algebraic-oriented languages like FORTRAN (1955) and ALGOL (1958), which needed the hyphen as a subtraction operator. Since the common punched card character sets of the time had no lower-case letters and no other special character that would be adequate for the purpose, those early languages had to do without multi-word identifiers.
It was only in the late 1960s that the widespread adoption of the ASCII character set made both lower case and the underscore character "_" universally available. Some languages, notably C, promptly adopted underscores as word separators; and underscore-separated compounds like "end_of_file" are still prevalent in C programs and libraries. Yet, some languages and programmers chose to avoid underscores and adopted CamelCase instead. Two accounts are commonly given for the origin of this convention.

The "Lazy Programmer" theory

One theory for the origin of the CamelCase convention holds that C programmers and hackers simply found it more convenient than the standard underscore-based style.
Indeed, the underscore key is inconveniently placed in most keyboards. Additionally, in some fonts the underscore character can be confused with a minus sign; it can be overlooked because it falls below the string of characters, or it can be lost entirely when displayed or printed underlined, or when printed on a dot-matrix printer with a defective pin or misaligned ribbon. Moreover, early compilers severely restricted the length of identifiers (for example, to 8 or 14 letters), or silently truncated all identifiers to that length. Finally, the small size of computer displays available in the 1970s encouraged the use of short identifiers. It was for these reasons, some claim, that many C programmers opted to use CamelCase instead of underscores, for it yielded legible compound names with fewer keystrokes and fewer characters.

The "Alto Keyboard" theory

Another account claims that the CamelCase style first became popular at Xerox PARC around 1978, with the Mesa programming language developed for the Xerox Alto computer. This machine lacked an underscore key, and the hyphen and space characters were not permitted in identifiers, leaving CamelCase as the only viable scheme for readable multiword names. The PARC Mesa Language Manual (1979) included a coding standard with specific rules for Upper- and lowerCamelCase which was strictly followed by the Mesa libraries and the Alto operating system.
The Smalltalk language, which was developed originally on the Alto and became quite popular in the early 1980s, may have been instrumental in spreading the style outside PARC. CamelCase was also used by convention for many names in the PostScript page description language (invented by Adobe Systems founder and ex-PARC scientist John Warnock). A further boost was provided by Niklaus Wirth — the inventor of Pascal — who acquired a taste for CamelCase during a sabbatical at PARC, and used it in Modula, his next programming language.

Spread to mainstream usage

Whatever its origins within the computing world, CamelCase spread to a wider audience in the 1980s and 1990s, when the advent of the personal computer exposed hacker culture to the world. CamelCase then became fashionable for corporate trade names, first in computer-related fields but later expanding further into the mainstream. Examples ranging from the 1970s to the 2000s give a history of the spread of the usage:

(1975) MicroSoft (now Microsoft)

(1977) CompuServe, UnitedHealthCare (now UnitedHealthcare )

(1979) MasterCard, SportsCenter, VisiCalc

(1980) EchoStar

(1982) MicroProse, WordPerfect

(1983) NetWare

(1984) BellSouth, LaserJet, MacWorks, iDEN, NeXT

(1985) PageMaker, EastEnders

(1986) SpaceCamp

(1987) ClarisWorks, HyperCard, PowerPoint

(1990) HarperCollins

(1991) SuperAmerica

(1992) OutKast (hip hop band), ThinkPad

(1993) AmeriCorps, EcoPark, ValuJet (now AirTran Airways), SolidWorks

(1994) PlayStation, easyJet (an early use of CamelCase with lowercase first letter)

(1995) WorldCom (now MCI), eBay

(1996) RadioShack (formerly Radio Shack)

(1997) TiVo

(1998) DaimlerChrysler, PricewaterhouseCoopers, iMac

(1999) BlackBerry, DragonForce, SpongeBob SquarePants, jetBlue

(2000) FedEx (formerly Federal Express), GlaxoSmithKline, PayPal

(2001) AmerisourceBergen, ChevronTexaco (now Chevron), GameCube

(2002) ConocoPhillips

(2003) MySpace

(2005) PetSmart (formerly PETsMART) This fashion has become so pervasive that people often apply it to names that don't use it officially, for example hypercorrecting Usenet to "UseNet", Transamerica to "TransAmerica", Photoshop to "PhotoShop", Firefox to "FireFox", Game Boy to "GameBoy", Macworld to "MacWorld", and Caltech to "CalTech".
During the dot-com bubble of the late 1990s, the lowercase prefixes "e" (for "electronic") and "i" (for "Internet", "information", or perhaps "intelligent") became quite common, giving rise to some CamelCase names like iPod and eBox.
In 1998, Dave Yost suggested using CamelCase for long chemical names such as AmidoPhosphoRibosylTransferase . In 1990 the city of SeaTac, Washington became the first city officially spelled in CamelCase.

History of the name

The original name of the practice, used in media studies, grammars, and the Oxford English Dictionary, was "medial capitals". The fancier names such as "InterCaps", "CamelCase", and variations thereof are relatively recent, and seem more common in computer-related communities.
The earliest known occurrence of the term InterCaps on Usenet is in an April 1990 post to the group alt.folklore.computers by Avi Rappoport, with BiCapitalization appearing slightly later in a 1991 post by Eric S. Raymond to the same group. The earliest use of the name "CamelCase" occurs in 1995, in a post by Newton Love. "With the advent of programming languages having these sorts of constructs, the humpiness of the style made me call it HumpyCase at first, before I settled on CamelCase. I'd been calling it CamelCase for years," said Newton, "The citation above was just the first time I'd used the name on USENET."
The name CamelCase isn't related to the "Camel book" (Programming Perl), which uses all-lowercase identifiers with underscores in its sample code.

Current usage in computing

Programming and coding style

Internal capitalization is sometimes recommended by the coding style guidelines written for source code (for example, the Mesa programming language and the Java programming language). The recommendations contained in some of these guidelines are supported by static analysis tools that check source code for adherence.
   These recommendations often distinguish between UpperCamelCase and lowerCamelCase, typically specifying which variety should be used for specific kinds of entities: variables, record fields, methods, procedures, types, etc.
   One widely used Java coding style dictates that UpperCamelCase be used for classes, and lowerCamelCase be used for instances and methods. Recognising this usage, some IDEs, such as Eclipse, implement shortcuts based on CamelCase. For instance, in Eclipse's Content assist feature, typing just the upper-case letters of a CamelCase word will suggest any matching class or method name (for example, typing "NPE" and activating content assist could suggest "NullPointerException").
   The original Hungarian notation for programming specifies that a lowercase abbreviation for the "usage type" (not data type) should prefix all variable names, with the remainder of the name in UpperCamelCase; as such it's a form of lowerCamelCase. CamelCase is the official convention for file names in Java and for the Amiga personal computer. Microsoft .NET recommends lowerCamelCase.
   The NIEM registry requires that XML Data Elements use UpperCamelCase and XML Attributes use lowerCamelCase.
   CamelCase is by no means universal in computing. Users of several modern programming languages, notably those in the Lisp and Forth families, nearly always use hyphens. Among the reasons sometimes given are that doing so doesn't require shifting on most keyboards, that the words are more readable when they're separated, and that CamelCase may simply not be reliably preserved in case-insensitive or case-folding languages (such as Common Lisp, that, while technically a case-sensitive language, canonicalizes (folds) identifiers to uppercase by default).

Wiki linking

Ward Cunningham's original wiki software used CamelCase to identify links to other wiki pages. This convention is still used by some wikis, such as JSPWiki and PMWiki. Wikipedia used to use CamelCase linking as well, but switched to explicit link markup (for example, with …) as have most wiki sites.

Current usage in natural languages

CamelCase has been used in languages other than English for a variety of purposes, including the ones below:

Orthographic markings

Camel case is sometimes used in the transcription of certain scripts, to differentiate letters or markings. An example is the rendering of Tibetan proper names like rLobsang: the "r" here stands for a prefix glyph in the original script that functions as tone marker rather than a normal letter.

Inflection prefixes

Camel case may also be used when writing proper names in languages that inflect words by attaching prefixes to them. In some of those languages, the custom is to leave the prefix in lower case, and capitalize the root.
This convention is used in Irish orthography as well as Scots Gaelic orthography; for example, ("in Galway"), from ("Galway"); ("the Scottish person"), from ("Scottish person"); ("to Ireland"), from ("Ireland).
Several Bantu languages also use this convention, for example, kiSwahili ("Swahili language" in Swahili) and isiZulu ("Zulu language" in Zulu).

Abbreviations and acronyms

In French, abbreviations such as OuLiPo (1960) were favored for a time as alternatives to acronyms.
CamelCase is often used to transliterate acronyms from alphabets where two letters may be required to represent a single character of the original alphabet, for example, DShK from Cyrillic ДШК.

Honorifics within compound words

In several languages, including English, pronouns and possessives may be capitalized to indicate respect, for example, when referring to the reader of a formal letter or to God. In some of those languages, the capitalization is customarily retained even when those words occur within compound words or suffixed to a verb. For example, in Italian one would write ("we offer to You respectful salutations") or ("adore Him").

Other uses

In German, all nouns carry a grammatical gender -- which, for roles or job titles, is usually masculine. Since the feminist movement of the 80s, some writers and publishers have been using the feminine title suffixes -in (singular) and -innen (plural) to emphasize the inclusion of females; but written with a capital 'I', to indicate that males are not excluded. Example: ("letters from [maleor] female readers") instead of ("letters from readers") or ("letters from female readers").

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