..Introduction To C Programming Language..
The C language
was invented at Bell Labs by Dennis Ritchie in 1972 to allow the
writing of the UNIX operating system, then developed by Ken Thompson and
Dennis Ritchie.
Dennis Ritchie. |
The UNIX operating system, born in the late 1960s - early 1970s, was written directly in assembly language for the machines which it was intended. born in the late 1960s - early 1970s, was written directly in assembly language for the machines which it was intended. If the assembly language for writing such a system, it was nevertheless not easy to use. Such language is in fact a particular type of processor, which makes the whole system should be rewritten to make it work on a new architecture. This is its main creator, Ken Thompson, wanted to use a language more quickly evolved to rewrite UNIX.
Among the languages available at the time, BCPL (Basic Combined
Programming Language for, which is a simplification of CPL), created by
Martin Richards in 1966, was interesting. Without going into detailed
descriptions, BCPL is a simple language, procedural, and not typed. Its
simplicity makes it easy to create BCPL compilers on machines of the
time, when resources were very limited (the first computer used by Keith
Thompson was to launch a Unix PDP-7, which had a memory of 4000 words
18 bits, or less than 9 KB). Ken Thompson has evolved to design the B
language, which he implemented the first UNIX machines. However, some
limitations of language B were UNIX could be rewritten in this language.
From
1971, Dennis Ritchie B did evolve to address these issues. Like the
programmers increment versions of their programs, Ritchie "Nudge" the
letter B to call the new language C. This evolution is "stabilized" to
1973, from which UNIX and UNIX system utilities have been rewritten
successfully in C.
Subsequently in 1978, Brian W. Kernighan documentation very active
language, and finally publish the book with reference Ritchie The C Programming Language. Often called K & R C language as specified in the first edition of this book.
In the
years that followed, the C language was carried on many other machines.
These ports were often made at the beginning, from the pcc compiler
Steve Johnson, but then the original compilers were developed
independently. During these years, every C compiler was written in
accordance with the specifications of K & R, but some added
extensions, such as data types or additional features, or different
interpretations of certain parts of the book (not necessarily very
precise). Because of this, it was less easy to write C programs that can run unchanged on many architectures.
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