C++: The Complete Reference

This chapter presents an overview of the C programming language, its origins, its
uses, and its underlying philosophy. Since C++ is built upon C, this chapter provides
an important historical perspective on the roots of C++. Much of what makes C++
what it is had its genesis in the C language.
The Origins of C
C was invented and first implemented by Dennis Ritchie on a DEC PDP-11 that used
the Unix operating system. C is the result of a development process that started with an
older language called BCPL. BCPL was developed by Martin Richards, and it
influenced a language called B, which was invented by Ken Thompson. B led to the
development of C in the 1970s.
For many years, the de facto standard for C was the version supplied with the Unix
version 5 operating system. It was first described in The C Programming Language by
Brian Kernighan and Dennis Ritchie (Englewood Cliffs, N.J.: Prentice-Hall, 1978). In the
summer of 1983 a committee was established to create an ANSI (American National
Standards Institute) standard that would define the C language once and for all. The
standardization process took six years (much longer than anyone reasonably expected).
The ANSI C standard was finally adopted in December 1989, with the first copies
becoming available in early 1990. The standard was also adopted by ISO (International
Standards Organization) and is now referred to as the ANSI/ISO C standard. For
simplicity, this book will use the term Standard C when referring to the ANSI/ISO C
standard. Today, all mainstream C/C++ compilers comply with Standard C. Standard
C is the foundation upon which C++ is built.
C Is a Middle-Level Language
C is often called a middle-level computer language. This does not mean that C is less
powerful, harder to use, or less developed than a high-level language such as BASIC
or Pascal, nor does it imply that C has the cumbersome nature of assembly language
(and its associated troubles). Rather, C is thought of as a middle-level language because
it combines the best elements of high-level languages with the control and flexibilityof
assembly language. Table 1-1 shows how C fits into the spectrum of computer
languages.
As a middle-level language, C allows the manipulation of bits, bytes, and
addresses--the basic elements with which the computer functions. Despite this fact
C code is also very portable. Portability means that it is easy to adapt software written
for one type of computer or operating system to another. For example, if you can easily
convert a program written for DOS so that it runs under Windows, that program is
portable.
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