Introduction to C Programming - Part 01

Computer Program

Computer Program

         Set of instructions given to the computer.

• Programmers write programs in various programming languages.
• Programming languages can be mainly divided into :

                    1. Low-level programming languages

                                            -   Machine Language

                                            -   Assembly Language

                    2.  High-level programming languages

Programming Languages

Low-level programming Languages

Machine Languages

–Consist of 1 s and 0 s

–Machine dependent

–Computer can directly understand its own machine language

–Tedious and error prone for programmers

       Example:

               11001010000100101000010101110100

            11000101010001110010101000110010

Assembly Languages

–  English-like abbreviations called mnemonics formed the basis

–  Clearer to humans but incomprehensible to computers

–  Need to translate to machine language using translator programs called assemblers

  Example:

             load  salary

             add   bonus

              store total

High Level Programming Languages

–  Instructions look almost like English and mathematical notations

–  Substantial tasks can be accomplished from a single statement

–  Easy for humans to understand

–  Translator programs convert high-level programming languages into machine language

       Example:

                     total = salary + bonus;

              – C, C++, Python, Visual Basic and Java are some of the high level programming languages.

Program Code Translation

Translator

  - Assemblers  (convert assembly language programs to machine language)

  - Compilers  (convert high-level language programs to machine language)

   - Interpreters (execute high-level language programs line by line)

History of C

          C language was evolved from two previous languages, BCPL and B by Dennis Ritchie at Bell Laboratories in 1972. C initially became widely known as the developing language of the UNIX operating system. C99 and C11 are revised standards for C programming language that refines and expands the capabilities of C.