C++ Primer Plus

The second obstacle to portability is language divergence. Certainly, that can be a problem with spoken languages. A Yorkshireman’s description of the day’s events may not be portable to Brooklyn, even though English is said to be spoken in both areas. Computer languages, too, can develop dialects. Although most implementers would like to make their versions of C++ compatible with others, it’s difficult to do so without a published standard describing exactly how the language works. Therefore, the American National Standards Institute (ANSI) created a committee in 1990 (ANSI X3J16) to develop a standard for C++. (ANSI had already developed a standard for C.) The International Organization for Standardization (ISO) soon joined the process with its own committee (ISO-WG-21), creating a joint ANSI/ISO effort to develop the standard for C++.

Several years of work eventually led to the International Standard (ISO/IEC 14882:1998), which was adopted in 1998 by the ISO, the International Electrotechnical Commission (IEC), and ANSI. This standard, often called C++98, not only refined the description of existing C++ features but also extended the language with exceptions, runtime type identification (RTTI), templates, and the Standard Template Library (STL). The year 2003 brought the publication of the second edition of the C++ standard (ISO/IEC 14882:2003); the new edition is a technical revision, meaning that it tidies up the first edition—fixing typos, reducing ambiguities, and the like—but doesn’t change the language features. This edition often is called C++03. Because C++03 didn’t change language features, we’ll follow a common usage and use C++98 to refer to C++98/C++03.

C++ continues to evolve, and the ISO committee approved a new standard August 2011 titled ISO/IEC 14882:2011 and informally dubbed C++11. Like C++98, C++11 adds many features to the language. In addition, it has the goals of removing inconsistencies and of making C++ easier to learn and use. This standard had been dubbed C++0x, with the original expectation that x would be 7 or 8, but standards work is a slow, exhaustive, and exhausting process. Fortunately, it was soon realized that 0x could be a hexadecimal integer (see Appendix A, “Number Bases”), which meant the committee had until 2015 to finish the work. So by that measure, they have finished ahead of schedule.

The ISO C++ Standard additionally draws on the ANSI C Standard because C++ is supposed to be, as far as possible, a superset of C. That means that any valid C program ideally should also be a valid C++ program. There are a few differences between ANSI C and the corresponding rules for C++, but they are minor. Indeed, ANSI C incorporates some features first introduced in C++, such as function prototyping and the const type qualifier.

Prior to the emergence of ANSI C, the C community followed a de facto standard based on the book The C Programming Language, by Kernighan and Ritchie (Addison-Wesley Publishing Company, Reading, MA, 1978). This standard was often termed K&R C; with the emergence of ANSI C, the simpler K&R C is now sometimes called classic C.

The ANSI C Standard not only defines the C language, it also defines a standard C library that ANSI C implementations must support. C++ also uses that library; this book refers to it as the standard C library or the standard library. In addition, the ISO C++ standard provides a standard library of C++ classes.

The C Standard was last revised as C99, which was adopted by the ISO in 1999 and ANSI in 2000. This standard adds some features to C, such as a new integer type, that some C++ compilers support.

Language Growth

Originally, the de facto standard for C++ was a 65-page reference manual included in the 328-page The C++ Programming Language, by Stroustrup (Addison-Wesley, 1986).

The next major published de facto standard was The Annotated C++ Reference Manual, by Ellis and Stroustrup (Addison-Wesley, 1990). This is a 453-page work; it includes substantial commentary in addition to reference material.

The C++98 standard, with the addition of many features, reached nearly 800 pages, even with only minimal commentary.

The C++11 standard is over 1,350 pages long, so it augments the old standard substantially.

This Book and C++ Standards