Friday, July 29, 2016

C Basics - Overview of C

C is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the UNIX operating system. C was originally designed for and first implemented on the UNIX operating system DEC PDP-11 computer in 1972. It has been closely associated with the UNIX system where it was developed. The language, however, is not tied to any one operating system or machine. The UNIX operating system, the C compiler, and essentially all UNIX applications programs have been written in C.

The C has now become a widely used professional language for various reasons.
  • C is procedural language
  • C is simple
  • C is portable
  • C has rich set of operators and datatype
  • C has facilities for structured programming
C features economy of expressions, modern control flow and data structures and rich set of operators. The powerful facilities offered by C to allow manipulation of direct memory addresses and data, even down to the bit level, along with C’s structured approach to programming cause C to be classified as a “medium level” programming language. It possesses fewer readymade facilities than a high level language, such as BASIC, but a higher level of structure than low level Assembler.

C provides a variety of data types. The fundamental types are characters, integers and floating point numbers of several sizes. In addition, there is a hierarchy of derived data types created with pointers, arrays, structures and unions. Expressions are formed from operators and operands; any expressions, including an assignment or a function call, can be a statement. Pointers provide for machine-dependent address arithmetic.

C provide the fundamental control flow constructions required for well-structured programs: statement grouping, decision making, selecting one of a set of possible cases, looping with termination test at the top or at the bottom, and early lop exit.

C offers only straightforward, single-thread control flow: tests, loops, grouping, and subprograms but not multiprogramming, parallel operations, synchronization, or co-routines.

Because the data types and control structures provided by C are supported directly by most computers, the run-time library required to implement self-contained program is tiny. The standard library functions are only called explicitly, so they can be avoided if they are not needed. Most can be written in C, and expect for the operating system they conceal, are themselves portable.

Although C matches the capabilities of many computers, it is independent of any particular machine architecture. With a little care it is easy to write portable programs, that is, programs that can be run without change on a variety of hardware. The standard makes portability issues explicit, and prescribes a set of constants that characterize the machine on which the program is run.

C language is used in developing Operating System, Network Drivers, Embedded System Software, Firmware, Device Driver, Compiler, Assembler, Interpreters, Simulators, etc.

Related topics:
Intro of C   |   Features of C   |   Applications of C   |   The Setup for C   |   Source Program in C   |   Program Startup and Termination in C   |   Program Structure in C   |   First Program in C   |   Must Know Terms in C

List of topics: C Programming

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