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Introduction to programming in C

Nihar Ranjan Roy

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History of C Programming language

The C programming language was designed by Dennis Ritchie at BellLaboratories in the early 1970s

In 1983 the American National Standards Institute (ANSI) began thestandardization process

In 1989 the International Standards Organisation (ISO) continued thestandardisation process

In 1990 a standard was finalised, known simply as Standard C Everything before this is known as K&R C Traditionally used for

systems programming.

Main source of documentation of K& R C The C Programming Language , by Brian Kernighan and Dennis Ritchie,

2nd Edition, Prentice Hall Referred to as K&R

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Characteristics of C Language

It recognizes the difference between lowercase and uppercase letters. It can be written with free format

Can write as many instructions as in a single line Its a structured programming language

During execution the control falls from the line at the top to the

Program consists of smaller units called functions.

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Building a C program#includeint main(void){...

}

Text Editor

Compiler 010010011110101

Programmer

Source Code

Object Code

___________ ________________ ________________ ________________

_

Linker

Loader

1110100001001.111010000111101 Executable

Code

Results

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Writing and editing programs Use any text editor (Ascii) available on your computer.

Example: windows (Edit,TC IDE,Notepad), Linux( Vi,Vim,emacs etc.) Compiling (windows)

With IDE ( Turbo C) Press Alt+F9

Command prompt ssue t e o ow ng comman tcc ename.c

Linking Running the program

Windows With IDE

Press CTRL+F9 Command Prompt

Issue the following command filename (hit enter) Linux

Issue the following command ./a.out or ./outputfilename ( hit enter)

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Structure of a C program

/* Preprocessor directives */

/* Global declarations */ #include int main(void)

int main(void){/*Local declarationsStatements*/}

/* other functions as required */

printf("Hello");return 0;

}

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My First C Program

#include /* comment */

int main(void)

tells compiler about stst anddard iinput and ooutput functions (i.e. printf + others)

main function

printf("Hello");return 0;

}begin

end

flag success

to operatingsystem

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Command Prompt(Windows) : Compiling & Running

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Turbo C IDE

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The Format of C

Statements are terminated withsemicolons

Indentation is ignored by the compiler. C is case sensitive - all keywords and

Standard Library functions are lowercase. Strin s are laced in double uotes

#include

/* comment */

int main(void){

rintf "Hello" Newlines are handled via \n

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return 0;}

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Problem

Write a program in C which asks the user what is your name?. Acceptsusers name and greets him as Hello,xxxx where xxxx is the name ofthe user.

What is your name?

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N arHello, Nihar

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2nd

Program

char name [30] ;declares a variable named name, which

can hold a string of up to 29characters (letter, digit, punctuation,etc.).

#includevoid main(){

printf ("What's your name? ");

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read your name into the variable name.

scanf("%s",name);printf("Hello, %s\n",name);}

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Problem

Write a program which accepts two integer numbers and displays itssum.

Enter two numbers:6 7The sum is 13

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3rd

Program

#includevoid main (){int a,b,sum;

We have made five changes to theoriginal program. We have

1. replaced the line defining name with onedefining other variables (a, b, and sum, alintegers)

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pr n n er wo num ers: ;scanf("%d %d",&a,&b);sum = a + b;printf("The sum is %d \n",sum);}

. c ange t e message n t e pr ntstatement

3. changed the format string and variablelist in the scanf statement

4. added the assignment statement sum = ab;

5. changed the format string and argumentlist in the final printf statement

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Conclusion & Queries

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