Welcome In The World Of ‘C’
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 1960. 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
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 1978 1989 1990
Traditional C Dennis Ritchie K&R C
Kernighan &Ritchie
ANSI C ANSI Committee ANSI/ISO C ISO Committee
Features Of ‘C’ 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.
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.
1) 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> stdio.h is header file.
It defines all symbolic constants. #define instuction defines value to a symbolic constant.
#define:ď&#x201A;§It
is a preprocessor compiler directive, not a statement. ď&#x201A;§Therefore it should not end with a semicolon. ď&#x201A;§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 â&#x20AC;&#x2DC;Câ&#x20AC;&#x2122; program must have one main() function section. It contains two parts 1) Declaration part: It declares all variables used in the executable part. 1) Executable part: It has atleast one statement.
main( No arguments
)
= main (void) Explicitly indicate no arguments
Link Section Definition Section Global Declaration Section main() function section { Declaration part Executable part } Subprogram section Function1 Function2 â&#x20AC;Ś user defined function
ď ąThere
are two ways to run programs written in a highlevel language. ď ąThe
ď ąThe
most common is to compile the program
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 onlyâ&#x20AC;Ś.. If we use higher level language then â&#x20AC;Ś 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. The compiler derives its name from the way it works, looking at the entire piece of source code and collecting and reorganizing the instructions.
Interpreter: which analyzes and executes each line of source code without looking at the entire program.
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.
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.
Types of languages (I) Lower level languages:Languages which are very near to machineâ&#x20AC;Ś. I.e. machine language, Assembly language. (II) Higher level languages:Languages which are very near to programmer rather than to machineâ&#x20AC;Ś. 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 generatedâ&#x20AC;Ś. - or what will be the logic for the program?
Block Diagram for making addition of two numbers : Output
Input No1. & No2.
PROGRAM
No1 + No2
Algorithm Specifies steps of doing the things Irrespective of any programming language 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
Read No1 and No2 from user
SUMMATION = NO1 + NO2
Write Summation on monitor
End
Files:- storage of logically related data 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<stdio.h> /* link section*/ void main() /* execution of program*/ { print(â&#x20AC;&#x153;hello worldâ&#x20AC;?); /*executable statement*/ }
I.e. “hello.c”, here “hello” is filename and “c” is file extension which indicates that hello is a ‘c program.