Unit-I Introduction to C 
                                                                                                                                                          
                     What is a Programming Language? 
                           •    A  Programming Languages is a set of rules that provides a way of telling a computer what 
                                operations to perform 
                           •    A programming language is a set of rules for communicating an algorithm 
                           •    It provides a linguistic framework for describing computations 
                           •     A programming language is a tool for developing executable models for a class of problem 
                                domains 
                           •    A programming language is a notational system for describing computation in a machine-
                                readable and a human-readable form                    
                     Levels of Programming Languages: 
                           •    Executable Machine Code 
                              Ex: Hex code or coding in 0s and 1s 
                      
                           •    Low-level Programming Languages 
                              Ex: Assembly language program, 8085, 8086 programming 
                      
                           •    High-level Programming Languages 
                              Ex: FORTRAN, COBOL, Basic, C, C++, Java, HTML, XML 
                      
                           •    HTML & XML are the high-level mark-up languages 
                     Concepts of Programming Language: 
                           •    English is a natural language. It has words, symbols and grammatical rules 
                           •    A programming language also has words, symbols and rules of grammar, called syntax 
                           •    Each programming language has different set of syntax rules 
                           •    Different programming languages are designed for different types of programs  
                     Types of Programming Languages 
                           •    First Generation Languages 
                                Ex: Machine language, hex code 
                           •    Second Generation Languages 
                                Ex: Assembly languages, 8085, 8086 
                      
                           •    Third Generation Languages: Closer to English, program written in source code 
                                Ex: Fortran, COBOL, C, C++, Visual Basic 
                      
                           •    Fourth Generation Languages: used with databases 
                                 Ex: query languages, report generators, form designers   
                      
                           •    Fifth Generation Languages 
                                 Ex: LISP, Scheme, SML, Prolog 
                      
                                                                                                                                            
                     Evolution of C language: 
                           •    C evolved from two previous languages, BCPL (Basic Combined Programming Language) 
                                and B  
                           •    BCPL developed in 1967 for writing OSes and compilers.  
                           •    B was used to create an early versions of UNIX OS at bell Laboratories in 1970 on a DEC 
                                PDP-7 computer.  
                           •    Both BCPL and B were typeless languages: the only data type is machine word  
                     History of C language: 
                           •    The C language developed from B by Dennis Ritchie at Bell Laboratories in 1972.  
                           •     It was named C for new language (after B)  
                           •     Initially, C used widely as the development language of the UNIX OS.  
                           •    Today, almost all new major OS are written in C including Windows  
                           •    The American National Standards Institute (ANSI) Committee approved C language in 1989, 
                                called ANSI C.  
                           •    Then, the document is referred to as ANSI/ISO 9899:1990.  
                           •     The second edition of Kernighan and Ritchie, published in 1988, this version called ANSI C, 
                                then used in worldwide.  
                           •    Historically, C programming language evolved from C89/C90/C95, C99 and the latest is C11. 
                     Introduction to C: 
                           •    The programming language C was developed in the early 1970s by Dennis Ritchie at Bell 
                                Laboratories 
                           •    It was named ‘C’ because many of its features were derived from an earlier language called 
                                ‘B’  
                           •    C  was  designed  for  implementing  system  software,  later  on  widely  used  for  developing 
                                portable application software 
                           •    C was developed by Dennis Ritchie in 1972 that took concepts from ALGOL, BCPL, and B.  
                           •    For many years, C was mainly used in academic institutions 
                           •    C was documented and popularized in the book The C Programming Language in 1978 by 
                                Kernighan and Ritchie 
                           •    In 1983, the American National Standards Institute (ANSI) started working on defining the 
                                standard for C 
                           •    This standard was approved in December 1989 and came to known as ANSI C 
                           •    In 1990, the International Standards Organization (ISO) adopted the ANSI standard  
                                                                       Taxonomy of C language                                                         
                      
                     Characteristics of C: 
                           •    C is a robust language 
                           •    Built-in functions and operators can be used to write complex C programs 
                           •    C compiler combines the features of assembly language and high-level language 
                           •    A high level programming language enables the programmer to concentrate on the problem 
                           •    Not worry about the machine code on which the program would be run  
                           •    Small size – C has only 32 keywords  
                           •    Extensive use of function calls  
                           •    Well suited for structured programming, provides easiness in debugging, testing and 
                                maintenance 
                           •    Loose typing - unlike PASCAL  
                           •    Structured language 
                           •    Stable language 
                           •    Quick language 
                           •    Facilitates low level (bitwise) programming 
                           •    Supports pointers to refer computer memory, array, structures, and functions 
                           •    Core language, learning other computer languages becomes much easier, if you know C 
                           •    Portable language, C program written for one computer can be run on another computer  
                           •    Extensible language, it enables the user to add his own functions to the C library 
                           •    Often treated as second best language, best language depends on the particular task to be 
                                performed 
                     C is the widely used professional language: 
                           •    It has high-level constructs 
                           •    It can handle low-level activities 
                           •    It produces efficient programs 
                           •    It can be compiled on a variety of computers 
                     Drawback: 
                           •    it has poor error detection which can make it off putting to the beginner 
                                                                       Features of C Language