C – Language Introduction

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  • The C language is a structure oriented programming language, developed at Bell Laboratories in 1972 by Dennis Ritchie
  • C programming language features were derived from an earlier language called “B” (Basic Combined Programming Language – BCPL)
  • C language was invented for implementing UNIX operating system
  • In 1978, Dennis Ritchie and Brian Kernighan published the first edition “The C Programming Language” and commonly known as K&R C
  • In 1983, the American National Standards Institute (ANSI) established a committee to provide a modern, comprehensive definition of C. The resulting definition, the ANSI standard, or “ANSI C”, was completed late 1988.

C programming language standards:

  • C89/C90 standard – First standardized specification for C language was developed by the American National Standards Institute in 1989. C89 and C90 standards refer to the same programming language.
  • C99 standard – Next revision was published in 1999 that introduced new features like advanced data types and other changes.

C11 and Embedded C language:

  • C11 standard adds new features to C programming language and library like type generic macros, anonymous structures, improved Unicode support, atomic operations, multi-threading and bounds-checked functions. It also makes some portions of the existing C99 library optional and improves compatibility with C++.
  • Embedded C includes features not available in C like fixed-point arithmetic, named address spaces, and basic I/O hardware addressing.
  • Operating systems, C compiler and all UNIX application programs are written in C language
  • It is also called as procedure oriented programming language. The C language is reliable, simple and easy to use. C has been coded in assembly language.

Features of C language:

C language is one of the powerful language. Below are some of the features of C language.

  • Reliability
  • Portability
  • Flexibility
  • Interactivity
  • Modularity
  • Efficiency and Effectiveness

Uses of C language:

The C programming language is used for developing system applications that forms a major portion of operating systems such as Windows, UNIX and Linux. Below are some examples of C being used.

  • Database systems
  • Graphics packages
  • Word processors
  • Spreadsheets
  • Operating system development
  • Compilers and Assemblers
  • Network drivers
  • Interpreters

Which level is C language belonging to?

There are 3 levels of programming languages. They are,

  1. Middle Level languages:
    Middle level languages don’t provide all the built-in functions found in high level languages, but provides all building blocks that we need to produce the result we want. Examples: C, C++
  2. High Level languages:
    High level languages provide almost everything that the programmer might need to do as already built into the language. Example: Java, Python
  3. Low Level languages:
    Low level languages provides nothing other than access to the machines basic instruction set. Example: Assembler

C language is a structured language:

Structure oriented language:

  • In this type of language, large programs are divided into small programs called functions
  • Prime focus is on functions and procedures that operate on the data
  • Data moves freely around the systems from one function to another
  • Program structure follows “Top Down Approach”
  • Examples: C, Pascal, ALGOL and Modula-2

Object oriented language:

  • In this type of language, programs are divided into objects
  • Prime focus is in the data that is being operated and not on the functions or procedures
  • Data is hidden and cannot be accessed by external functions
  • Program structure follows “Bottom UP Approach”
  • Examples: C++, JAVA and C# (C sharp)

Non structure oriented language:

  • There is no specific structure for programming this language. Examples: BASIC, COBOL, FORTRAN

Key points to remember in C language:

  1. The C language is a structure oriented programming language developed by Dennis Ritchie.
  2. The C language is belonging to middle level programming language.
  3. Operating system programs such as Windows, Unix, Linux are written in C language.
  4. C89/C90 and C99 are two standardized editions of C language.
  5. C has been written in assembly language.

Reference C language E-books & research papers:

  • [ANSI 89] American National Standards Institute., American National Standard for Information  Programming Language C, X3 159-1989
  • [Kernighan 78] B. W. Kernighan and D. M. Ritchie, The C Programming Language, Prentice-Hall: Englewood Cliffs, NJ, 1978. Second edition, 1988.
  • [Thinking 90] C* Programming Guide, Thinking Machines Corp.: Cambridge Mass., 1990.

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