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.
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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