Introduction – Programming C

C is a programming language it is designed by DENNIS RITCHIE in 1972 at AT & T [American Telephone and telegraphs]  Bell labs in USA.  C is most popular general purpose language.

BRIEF HISTORY OF C LANGUAGE:

            In 1960’s COBOL was being used for commercial applications and FORTRAN for scientific and engineering applications.  At this stage people started to develop a language which is suitable for all possible applications.  Therefore an international committee was setup to develop such a language ALGOL 60 was released.  It was not the generality a new language called CPL  [Combine Programming Language] was developed at Cambridge University then some other features were added to this language a new language called BCPL [Basic combine programming language] developed by MARTIN RICHARDS at Cambridge University.  Then B language was developed by KENTHOMSON at AT &T Bell labs.

            DENNIS RITCHIED inherited the features of B and BCPL, added some of its own feature and developed C language in 1972.

Features of C Language:

  1. C is structured programming language with fundamental flow chart constructions.
  2. C is highly portable programming language.  The programs return for one computers can be run on another with or without any modifications.
  3. The programs return in C are efficient and fast.
  4. C improves by itself it has several predefined functions.
  5. C has only 32 keywords.
  6. C supports all data conversions and mixed mode operators.
  7. Dynamic memory storage allocation is possible with C.
  8. C is simple and versatile programming language.
  9. C easily manipulate with bytes, bits and address.
  10. C has a richest of operators.         
  11. Extensive verities of data types such as pointers, structures, Unions etc., available in C.
  12. Recursive function calls for algorithmic approach is possible with C.
  13. Mainly we are using the C language to implement the system software those are compilers, text editors, Network drives, data base utilities and finally the operating systems.
  14. C compiler combines the capabilities of assembly level language with the features of high level language.  So it is called as middle level language.

Important Points

  1. C is a case sensitive programming language. C statements are entered in lower case letters only.
  2. Every C statement must be terminated by a semicolon ( ; ) except preprocessor statements and function definition.
  3. C is a function oriented language.  Any C program contains one or more functions.  Mainly one function is necessary by the name called main. Without main we cannot execute C Programs.
  4. A function is represented by a function name with a pair of parenthesis.

COMPUTER: Computer is an electronic device, which has memory and performs arithmetic and logical operations.

Input: The data entered in the computer is called input. Ex:- Keyboard, mouse, joy stick etc.,

Output: The resultant information obtained by the computer is called output. Ex:- Through Screen, Printer etc.,

Program: A sequence of instructions that can be executed by the computer is called program.

Software: A group of program to operate and control the computer is called software

Hardware: All the physical components or units of computer system connected to the computer circuit is called hardware.

Operating System: It is an interface between user and the computer.  In other words, operating system is a complex set of programs,  that manage the resources of a computer. Resource include input, output, processor etc.,  So operating system is a Resource manager.

Language: It consists of a set of executable instructions.

Package: It is designed by any other language with limited resources.

Various steps involved in program or Application development:

 The following steps are involved in program development.

  1. Problem definition
  2. Analysis and Design
  3. Algorithms
  4. Flow Chart
  5. Coding and Implementation
  6. Debugging ( errors) and testing
  7. Documentation
  1. Problem Definition: Problem definition phase is a clear understanding of exactly what is needed for creating a workable solution.  We must know exactly what we want to do before we do a problem.  It involves three specifications regarding a proper definition.
  • Input Specification
  • Output Specification
  • Processing
  • Analysis and Design:  Before going to make a final solution for the problem, the problem must be analyzed outline solution is prepared in the case of simple problems. But in the case of complex problems, the main problem is divided into sub problems called modules.  These modules can be handled and can be solved independently. When the task is too big, it is always better to analyze the task, such that, it can be divided into number of modules and seek solution for each.
  • Algorithms: Once the problem is divided into number of modules, the logic for solving each module can be developed.  The logic is expressed step by step.  A step by step procedure to solve the given problem is called algorithm. An algorithm is defined as a finite set of instructions which accomplish a particular task.  An algorithm can be described in a natural language like English.
  • Flow Chart: After completion of algorithm, the program can be visualized by drawing a flow chart. A flow chart is nothing but a graphical or symbolic representation of how instructions will be executed one after another.
  • Coding and Implementation: Coding is a process of converting the algorithm solution of flow chart in computer program.

In this process each and every step of algorithm is converted to instructions of selected computer programming language. Before selecting

the programming language we must follow three considerations.

  • Nature of problem
  • Programming language available.              
  • Limitations of computer
  • Debugging and Testing:-

Debugging: Before loading the program into the computer we must correct all the errors.  This process is called debugging. There are three types of errors.

            *Syntax error

            *Runtime error

            *Logical error

Testing:- It is very important to test the program written to achieve a specific task.  Testing is running the program with known data and known result.

  • Documentation:- It is the most important aspect of programming.  It is a continuous  process. To keep the copy of continuous process.  To keep the copy of all the phases (involving) in parts, definition, analysis and designing, algorithm, flow chart, coding and implementation, debugging and testing are the parts of the documentation.  This phase involves to produce written document for the user.
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