Welcome In The World Of ‘C’

 TEXT BOOK: Programming in ANCI ‘C By: E Balagurusamy. TMH  Reference Books: 1) The ‘C Programming Language By: Kernighan and Ritchie. PHI Second Edition. 2) Let Us ‘C By: Yashwant Kanitkar

Teaching Scheme  During a week 3 Lectures + 1 Tutorial 1 Practical/Laboratory of two hour.  Marks system: Theory External Exam60 Practical Exam / Viva 50 Internal (Avg. of 3 exams)36 Attendance 4 Total 150

Importance of Subject  ‘C is the base language of any other programming language.  To be a Good Programmer one must know fundamentals of C programming language.

History of ‘C’  Root of the morden language is ALGOL It’s first computer language to use a block structure. It gave concept of structured programming.  In 1967, Martin Richards developed a language, BCPL (Basic Combined Programming Language)

 In 1970,by Ken Thompson created a language called as ‘B’. It used to create early version of Unix.  In 1972,by Dennis Ritchie introduced new language called as ‘C’.

1972 Traditional C Dennis Ritchie 1990 ANSI/ISO C ISO Committee 1978 K&R C Kernighan &Ritchie 1989 ANSI C ANSI Committee

 It is a robust language.  Programs written in ‘C’ are efficient and fast. (Because of variety of data types and powerful operators)  Highly Portable. (related to OS)  Well suited for structured programming.  Ability to extend itself. Features Of ‘C’

Program & Programming Language Program:- A Set of instructions which When carried out by processor for some Specific input, generates specific output. Programming language:- A specific manner of writing a program with some Predefined rules, symbols & their use as a part of language. i.e. Pascal, C, C++, VC++, JAVA, VB.

Basic structure of ‘C’ 1)Documentation Section :- It has set of comment lines(name of program, author details). What is Comment line??  To guide a programmer. To write a note for function,operation,logic in between a program.  Non-executable statement.  Can’t be nested. e.g:- /* Hello /* abc */ Hi */ ERROR.

2)Link Section :- It provides instructions to the compiler to link function from the system library. # include Directive:-  To access the functions which are stored in the library, it is necessary to tell the compiler, about the file to be accessed. Syntax:- #include  stdio.h is header file.

It defines all symbolic constants. #define instuction defines value to a symbolic constant. #define:-  It is a preprocessor compiler directive, not a statement.  Therefore it should not end with a semicolon.  Generally written in uppercase.

Some variables that are used in more than on function, such variables (global variables) declared in the global declaration section. It also declares all the user-defined function.

Every ‘C’ program must have one main() function section. It contains two parts 1) Declaration part: It declares all variables used in the executable part. 2) Executable part: It has atleast one statement.

main( ) = main (void) No arguments Explicitly indicate no arguments

Documentation section Link Section Definition Section Global Declaration Section main() function section { Declaration part Executable part } Subprogram section Function1 Function2 … user defined function

 There are two ways to run programs written in a high- level language.run  The most common is to compile the programcompile  The other method is to pass the program through an interpreter.

Compiler Why compiler is require ? As machine (a processor) can operate On binary code instruction only….. If we use higher level language then … For execution of the program we must Convert it to lower level / machine level Code.

Means, A program that translates source code into object code.programsource code object code The compiler derives its name from the way it works, looking at the entire piece of source code and collecting and reorganizing the instructions. instructions Interpreter: which analyzes and executes each line of source code without looking at the entire program.executes

Advantage of interpreter: It can execute a program immediately. Compilers require some time before an executable program emerges. But, However, programs produced by compilers run much faster than the same programs executed by an interpreter.run

C Compiler - checks for syntax errors if any - on success coverts ‘C source code into object code form – which is nearer to machine…

Linker: A linker is a program that combines object modules to form an executable program.program modules

Types of languages (I) Lower level languages:- Languages which are very near to machine…. I.e. machine language, Assembly language. (II) Higher level languages:- Languages which are very near to programmer rather than to machine…. I.e. C++,Visual C++,Visual basic,Java.

Block Diagram: Represents only -> what should be the input? -> what will be the output? - One need not to worry about how the result generated…. - or what will be the logic for the program?

Input No1. & No2. PROGRAM No1 + No2 Output Block Diagram for making addition of two numbers :

Algorithm Specifies steps of doing the things Irrespective of any programminglanguage Example: Addition of two numbers Step 1: [Read two numbers] Read(no1) Read(no2) Step 2:[add two numbers into sum] summation = no1 + no2 Step 3:[Display the result] write (summation)

Flowchart Represents the flow of program Symbols:- Start-Begin/End Input/Output Rectangle Process box/operation box Decision Box Connector

Flowchart-example Example: To add two numbers and display the result. Start SUMMATION = NO1 + NO2 End Read No1 and No2 from user Write Summation on monitor

Files:- storage of logically relateddata Directory:- Placeholder which can store files and subdirectories within them. File Extension:- special postfix attached to each file which indicates type of the file.

/* print hello*/ #include /* link section*/ void main() /* execution of program*/ { print(“hello world”); /*executable statement*/ }

I.e. “hello.c”, here “hello” is filename and “c” is file extension which indicates that hello is a ‘c program.