What is C++?
C++ (pronounced "see plus plus") is a general-purpose computer programming language. It is a statically typed free-form multi-paradigm language supporting procedural programming, data abstraction, object-oriented programming, and generic programming. Since the 1990s, C++ has been one of the most popular commercial programming languages.
Bell Labs' Bjarne Stroustrup developed C++ (originally named "C with Classes") in 1983 as an enhancement to the C programming language. Enhancements started with the addition of classes, followed by, among many features, virtual functions, operator overloading, multiple inheritance, templates, and exception handling. The C++ programming language standard was ratified in 1998 as ISO/IEC 14882:1998, the current version of which is the 2003 version, ISO/IEC 14882:2003. A new version of the standard (known informally as C++0x) is being developed.
History
Stroustrup began work on C with Classes in 1979. The idea of creating a new language originated from Stroustrup's experience programming for his Ph.D. thesis. Stroustrup found that Simula had features that were very helpful for large software development but was too slow for practical uses, while BCPL was fast but too low level and unsuitable for large software development. When Stroustrup started working in Bell Labs, he had the problem of analyzing the UNIX kernel with respect to distributed computing. Remembering his Ph.D. experience, Stroustrup set out to enhance the C language with Simula-like features. C was chosen because it is general-purpose, fast, and portable. Besides C and Simula some other languages which inspired him were: ALGOL 68, Ada, CLU and ML. At first, class (with data encapsulation), derived class, strong type checking, inlining, and default argument were features added to C, via the Cfront front-end. The first commercial release occurred in October 1985.
In 1983, the name of the language was changed from C with Classes to C++. New features that were added to the language included virtual functions, function name and operator overloading, references, constants, user-controlled free-store memory control, improved type checking, and new comment style (//). In 1985, the first edition of The C++ Programming Language was released, providing an important reference to the language, as there was not yet an official standard. In 1989, Release 2.0 of C++ was released. New features included multiple inheritance, abstract classes, static member functions, const member functions, and protected members. In 1990, The Annotated C++ Reference Manual was released and provided the basis for the future standard. Late addition of features included templates, exceptions, namespaces, new casts, and a Boolean type.
As the C++ language evolved, a standard library also evolved with it. The first addition to the C++ standard library was the stream I/O library which provided facilities to replace the traditional C functions such as printf and scanf. Later, among the most significant additions to the standard library, was the Standard Template Library.
After years of work, a joint ANSI-ISO committee standardized C++ in 1998 (ISO/IEC 14882:1998). For some years after the official release of the standard in 1998, the committee processed defect reports, and published a corrected version of the C++ standard in 2003. In 2005, a technical report, called the "Library Technical Report 1" (often known as TR1 for short) was released. While not an official part of the standard, it gives a number of extensions to the standard library which are expected to be included in the next version of C++. Support for TR1 is growing in almost all currently maintained C++ compilers.
No one owns the C++ language; it is royalty-free. The standard document itself is, however, not available for free.
Future development
C++ continues to evolve to meet future requirements. One group in particular, Boost.org, works to make the most of C++ in its current form and advises the C++ standards committee as to which features work well and which need improving. Current work indicates that C++ will capitalize on its multi-paradigm nature more and more. The work at Boost.org, for example, is greatly expanding C++'s functional and metaprogramming capabilities. The C++ standard does not cover implementation of name decoration, exception handling, and other implementation-specific features, making object code produced by different compilers incompatible; there are, however, 3rd-party standards for particular machines or OSs which attempt to standardise compilers on those platforms, for example C++ ABI.
C++ compilers still struggle to support the entire C++ standard, especially in the area of templates — a part of the language that was more-or-less entirely conceived by the standards committee. One particular point of contention is the export keyword, intended to allow template definitions to be separated from their declarations. The first compiler to implement export was Comeau C++, in early 2003 (5 years after the release of the standard); in 2004, beta compiler of Borland C++ Builder X was also released with export. Both of these compilers are based on the EDG C++ frontend. It should also be noted that many C++ books provide example code for implementing the keyword export (Ivor Horton's Beginning ANSI C++, pg. 827) which will not compile, but there is no reference to the problem with the keyword export mentioned. Other compilers such as Microsoft Visual C++ and GCC do not support it at all. Herb Sutter, secretary of the C++ standards committee, has recommended that export be removed from future versions of the C++ standard [1], but finally the decision was made to leave it in the C++ standard.
Other template issues include constructions such as partial template specialisation, which was poorly supported for several years after the C++ standard was released.
The name "C++"
This name is credited to Rick Mascitti (mid-1983) and was first used in December 1983. Earlier, during the research period, the developing language had been referred to as "C with Classes". The final name stems from C's "++" operator (which increments the value of a variable) and a common naming convention of using "+" to indicate an enhanced computer program, for example: "Wikipedia+". According to Stroustrup: "the name signifies the evolutionary nature of the changes from C". C+ was the name of an earlier, unrelated programming language.
Some C programmers have noted that if the statements x=3; and y=x++; are executed, then x==4 and y==3; x is incremented after its value is assigned to y. However, if the second statement is y=++x;, then y==4 and x==4. Following such reasoning, a more proper name for C++ might actually be ++C. However, c++ and ++c both increment c, and, on its own line, the form c++ is more common than ++c. However, the introduction of C++ did not change the C language itself, so an even more accurate name might be "C+1".
Stroustrup addresses this debate in the preface of later editions of his book, The C++ Programming Language, adding that another interpretation of the name "C++" might be inferred from the appendix of George Orwell's Nineteen Eighty-Four. Of the three segments of the fictional language Newspeak, the "C vocabulary" is the one dedicated to technical terms and jargon. "Doubleplus" is the superlative modifier for Newspeak adjectives. Thus, "C++" might hold the meaning "most extremely technical or jargonous" in Newspeak.
When Rick Mascitti was questioned informally in 1992 about the naming, he indicated that it was given in a tongue-in-cheek spirit. He never thought that it would become the formal name of the language.
Philosophy
In The Design and Evolution of C++ (1994), Bjarne Stroustrup describes some rules that he uses for the design of C++. Knowing the rules helps to understand why C++ is the way it is. The following is a summary of the rules. Much more detail can be found in The Design and Evolution of C++.
- C++ is designed to be a statically typed, general-purpose language that is as efficient and portable as C
- C++ is designed to directly and comprehensively support multiple programming styles (procedural programming, data abstraction, object-oriented programming, and generic programming)
- C++ is designed to give the programmer choice, even if this makes it possible for the programmer to choose incorrectly
- C++ is designed to be as compatible with C as possible, therefore providing a smooth transition from C
- C++ avoids features that are platform specific or not general purpose
- C++ does not incur overhead for features that are not used
- C++ is designed to function without a sophisticated programming environment
Stanley B. Lippman documents in his in-depth book "Inside the C++ Object Model" (1996) how compilers convert C++ program statements into an in-memory layout. Lippman worked on implementing and maintaining C-front, the original C++ implementation at Bell Labs.
About this Terminology
This terminology is from The Wikipedia which is published under the GNU Free Documentation License.