INTRODUCTION TO C PROGRAMMING Unit - 01

INTRODUCTION TO PROGRAMMING   Unit - 01

What is C Language?

C is a general-purpose computer programming language.

C is also said to be structures programming language or function oriented .                                           programming language

C is a High level programming language.

C is a programming language developed at AT & T’s Bell Laboratories of USA in                            1972. It was designed and written by a man named Dennis Ritchie. In the                                            late seventies C began to replace the more familiar languages of that time                      like PL/I, ALGOL, etc

Why do we use C?

C language is used to create applications or software

Initially, C was developed to create an operating system called UNIX. 

The popular software like Linux OS, PHP & MySQL are created using C                                                  language.

Why do we use C?        

Generally C Language is used to create the following…

·              Operating Systems

·              Language Compilers

·              Assemblers

·              Interpreters

·              Text Editors

·              Network Drivers

·  Databases

History of C Language?

C Language was developed by Dennis Ritchie in the year of 1972

Born                    – September 9, 1941

Profession         – Computer Scientist

Place                   – Bell Labs, US

Known As          – Father of C & UNIX

Awards   – Turing Award(1983)

                 National Medal of Technology(1998)

                 IEEE Medal(1990)

                 Computer Pioneer Award(1994)

                 Computer History Museum Fellow(1997)

                 Harold Pender Award(2003)

Died                    – October 12, 2011

·     Algorithms

An Algorithm is step-by-step method of solving a problem . It is commonly used for data processing calculation and other related computer and mathematical operation.

An algorithm is a set of instruction design to perform spacify task. This can be simple process that multiplying two numbers .

Charactistic of Algorithm-

Input – The operation algorithm:-     algorithm receives zero or more inputes

·       Output- the Algorithm must produce at least one output.

·       Finiteness – An Algorithm must terminate infinite amount of time .

·       Effectiveness – each step in algorithm should be simple and very basic

·       Definiteness – Every step in algorithm most be unambiguous.

Representation of Algorithm

1)    As a Program

2)    As a Flow chart

3)    As a Pseudo Code

Ex of Algorithm—

Step 1- Start

Step 2 –Input /radius of circle

Step 3 – Area=^*r*r

Step 4- print Area

Step 5 – Stop.

·    Flow-charts –

A flow chart is a pictorial representation as an algorithm .It can be defined as a sequence of diagrammatic representation of an algorithm.

A flowchart is a type of diagram that represents a workflow or process. A flowchart can also be defined as a diagrammatic representation of an algorithm, a step-by-step approach to solving a task.

NEED OF FLOW CHART SYMBOLS :-

A flow chart uses boxes of different types shapes to denote different type of instruction .The use of symbols having standardized meaning makes it easier to communicate program logic through flow chart . This is because use to standard symbol in a flow chart enables anyone using the flow chart to interpret the logic easily .

        Basic Flow Chart Symbols –

      The basic flow chart symbols standardize by the American National Standards Institute [ANSI] . Their function are describe below –

Basic Symbol of flow chart  -

(i)  Terminal / Start :-  It is the first and the last symbol in flow chart.

(ii)  Input / Output :- They also indicates instruction to input / output                                                                                                         data from / to a storage device

(iii)  Processing :- A processing symbol represents arithmetic and data movement instruction . It is indicate all arithmetic process of adding , subtraction , multiplying and dividing . They also indicates logical proves of moving data from one memory location to another

Note:-   Processing [ used when there in assignment operator (=) or arithmetic operator ( + , - , * , /).

(iv)  Decision :- A decision symbol indicates a decision point , which is a point at which a branch to one of two or more alternative path is possible . A decision symbol also accounts for all possible exit path depending on the result of decision .

(v) Flow Lines :- In flow chart , use of flow lines with arrow heads indicates flow of operation , normal flow of flow chart is from top-to-bottom and left-to-right

(vi) Connectors :- When the flow chart spreads over more than one page it is useful to utilize connector symbol as a substitute for flow lines                                      
 

Ex- of Flow chart:-

 ·       Programming Languages

Program :- Program is a set of instruction which is written in sequence manners using syntax of any programming language.

Programming  Language -  Computer language or programming language is a language acceptable to computer system and the process of writing instruction in such a language is called programming or coding.

Types of programming language –

Low level language –

1.        Machine Language –This is the 1^st generation language and computer works this language . This is also known as Low level language here all instruction where given is binary form and is transferd to machine language . It is very difficult for write or read instruction written in binary form

2.       Assembly language – This is the 2^nd generation language . The symbolic instruction language is called assembly . To execute these instruction all mnemonics are help of translator known as Assembler

High- level language –

This is the 3^rd generation language .In this language instruction are written using English language with symbol and digits . It is Machine in depended language . 

·       Linking and Loading

Linking- Linking is the process of collecting and combining various piecas of code and data into a single file that can be loaded into memory and executed

Loader – The job of loader is to load the program from secondry memory to main memory for execution

Static Loader – Load the program from secondary to main memory before the compileson

Linking and Loading are the utility programs that play a important role in the execution of a program. Linking intakes the object codes generated by the assembler and combines them to generate the executable module. On the other hand, the loading loads this executable module to the main memory for execution.

Loading:
Bringing the program from secondary memory to main memory is called Loading.

Linking:
Establishing the linking between all the modules or all the functions of the program in order to continue the program execution is called linking.

Differences between Linking and Loading:

1.      The key difference between linking and loading is that the linking generates the executable file of a program whereas, the loading loads the executable file obtained from the linking into main memory for execution.

2.     The linking intakes the object module of a program generated by the assembler. However, the loading intakes the executable module generated by the linking.

3.     The linking combines all object modules of a program to generate executable modules it also links the library function in the object module to built-in libraries of the high-level programming language. On the other hand, loading allocates space to an executable module in main memory.

·       Testing and Debugging

Testing :- (i) It is the process to find error

                            (ii) Testing can be manual or automated

                            (iii) Testing is done by tester  

                            (iv) Testing is display of error

Debugging :-

   (i) It is the process to correct the error find debugging testing

                             (ii) Debugging is always manual .It can not be automated

                             (iii) Debugging is done by programmer or developer

                             (iv) Debugging is deducting process  

·      Documentation –

 While writing programs it is a good programming practice to make a brief explanatory segments . This explanatory note is called a comment .It explain how to program works and how to interact with it Thus it helps other programmers to understand the program.

There are two types of documentation

(i) Internal Documentation :- This documentation is a comment statement within a program .It describe the function of the program pr program segment . these statement are not translated to machine language .

(ii) External Documentation :- This documentation is an executable statement in a program . It may be message to the user to respond to the program requirement  

·       Programming Style-Names:-

Programming style also known as Code Style. It is set of rules pr guidelines used when writing the source code for a program by following a particular programming style will hop programming style to read & understand source code & help to a void corroding errors.