C++

C++ (pronounced /ˌsiːˌplʌsˈplʌs/) is a general-purpose programming language. C++ is regarded as a mid-level language, as it comprises a combination of both high-level and low-level language features.[1] It is a statically typed, free-form, multi-paradigm, usually compiled language supporting procedural programming, data abstraction, object-oriented programming, and generic programming.
Bjarne Stroustrup developed C++ in 1979 at Bell Labs as an enhancement to the C programming language and named it "C with Classes". In 1983 it was renamed to C++. Enhancements started with the addition of classes, followed by, among other 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.

Language standard
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, 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.
While the C++ language is royalty-free, the standard document itself is not freely available.

[edit] Etymology
According to Stroustrup: "the name signifies the evolutionary nature of the changes from C".[3] During C++'s development period, the language had been referred to as "new C", then "C with Classes". The final name is credited to Rick Mascitti (mid-1983) and was first used in December 1983. When 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.[citation needed] It stems from C's "++" operator (which increments the value of a variable after evaluating it) and a common naming convention of using "+" to indicate an enhanced computer program. ABCL/c+ was the name of an earlier, unrelated programming language.

[edit] Philosophy
In The Design and Evolution of C++ (1994), Bjarne Stroustrup describes some rules that he uses for the design 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 (the "zero-overhead principle")
C++ is designed to function without a sophisticated programming environment
Inside the C++ Object Model (Lippman, 1996) describes how compilers may convert C++ program statements into an in-memory layout. Compiler authors are, however, free to implement the standard in their own manner.

[edit] Standard library
The 1998 ANSI/ISO C++ standard consists of two parts: the core language and the C++ standard library; the latter includes most of the Standard Template Library (STL) and a slightly modified version of the C standard library. Many C++ libraries exist which are not part of the standard, and, using linkage specification, libraries can even be written in languages such as C, Fortran, Pascal, or BASIC. Which of these are supported is compiler dependent.
The C++ standard library incorporates the C standard library with some small modifications to make it work better with the C++ language. Another large part of the C++ library is based on the STL. This provides such useful tools as containers (for example vectors and lists), iterators (generalized pointers) to provide these containers with array-like access and algorithms to perform operations such as searching and sorting. Furthermore (multi)maps (associative arrays) and (multi)sets are provided, all of which export compatible interfaces. Therefore it is possible, using templates, to write generic algorithms that work with any container or on any sequence defined by iterators. As in C, the features of the library are accessed by using the #include directive to include a standard header. C++ provides 69 standard headers, of which 19 are deprecated.
Using the standard library — for example, using std::vector or std::string instead of a C-style array — can help lead to safer and more scalable software.
The STL was originally a third-party library from HP and later SGI, before its incorporation into the C++ standard. The standard does not refer to it as "STL", as it is merely a part of the standard library, but many people still use that term to distinguish it from the rest of the library (input/output streams, internationalization, diagnostics, the C library subset, etc.).
Most C++ compilers provide an implementation of the C++ standard library, including the STL. Compiler-independent implementations of the STL, such as STLPort, also exist. Other projects also produce various custom implementations of the C++ standard library and the STL with various design goals.

[edit] Hello world program
The following is a Hello world program which uses the C++ standard library stream facility to write a message to standard output.[4]
#include // provides std::cout

int main()
{
std::cout << "Hello, world!\n";
}