Introducion to C Programming

7/30/2019 Introducion to C Programming

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INTRODUCTION TO C


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INTRODUCTION TO C

C was developed by Dennis Ritchie at Belllaboratory in 1972

It is an upgrade version of languages B and

BCPL.


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Features of C

It is a structured programming language.

It is highly portable.

It is a middle level language. It is a case sensitive language.

It uses Top-Down approach.

It is a Free form language.etc,.


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Steps in learning C

CharacterSet

ProgramsInstructionsTokens


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C Character Set

C Character Set

ExecutionCharacter Set

SourceCharacter Set

SpecialCharacters

DigitsAlphabets EscapeSequence

WhiteSpaces


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C Character Set (Cont)

Source Character Set

It is used to construct the statements in theprogram.

Executable Character Set

These characters are employed at the time ofexecution i.e. they have effects only when the

program is being executed.


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Source Character Set

Letters a to z ,A to Z

Digits 0 to 9

Special Characters ! @ # $ % ^ & * ( ) _ - += \ | { } [ ] etc,.

White Spaces Blank Space ,Horizontaltab, New line, Verticaltab etc,.


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Special characters Comma , Period or dot . Semicolon ; Colon :

Apostrophe

Quotation mark Exclamation mark ! Vertical bar |

Back Slash \ Tilde ~ Underscore - Dollar $

Question mark ?


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Ampersand & Caret ^

Asterisk * Minus - Addition + Lesser than Parenthesis () Bracket [] Braces {}

Percentage % Hash # Equal to = At the rate @


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Executable Character Set

Characters Escape Sequence

Back Space \b

Horizontal Space \t

Vertical Space \v

Newline \n


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C Tokens (Cont)

C Tokens

Identifiers

Eg:main,

avg

Keywords

Eg: int,

for

operators

Eg: +

-

Strings

Eg: ab

spIsymbol

Eg: #

$ %

Constants

Eg:17,

15.5


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Executing a C Program

Creating the Program

Compilation

Linking

Execution


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Executing a C Program (Cont)

Enter the program in a C editor.

Save the program (File Save) or F2.Use the extension .c for saving the file.

Eg: sample.c

Compile the program(Compile Compile)

or Alt+F9. Run the program(Run Run) or Ctrl+F9.


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Executing C program using UNIX

Enter the program in vi editor.

Save the file using :wq

Use the extension .c for saving the file.Eg: sample.c

Compile the program.

Eg: cc sample.c (or) gcc sample.c Run the program using a.out.


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Structure of C programDOCUMENTATION SECTION

PREPROCESSOR SECTION

DEFINITION SECTION

GLOBAL DECLARATION SECTION

main(){

Declaration part;Executable Part;

}sub program section{

Body of the subprogram;}


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Documentation Section It contains the comment lines.

Preprocessor Section It is used to link library files.

Global Declaration Section

The Global declaration section comes at thebeginning of the program and they are visibleto all parts of the program.

Declaration Section It describes the data to be used within the

function.

Executable Part

It contains the valid statements.


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C Programs C program may have many functions. One and only one of the functions MUST BE

named main.

main is the starting point for the program. main and other functions in a program are

divided into two sections, declarationsection and statement section.


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Preprocessor Directives

Special instructions to the preprocessorthat tells how to prepare the program forcompilation

E.g: include : tells the processor toinclude information from selected librariesknown as header filese.g.


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Comments (Program documentation)

The compiler simply ignores commentswhen it translates the program intoexecutable code.

To identify a comments, C uses opening/* and closing */ comment tokens.


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Comments (Cont)

Comments can appear anywhere in aprogram.

Comments are also found wherever it is

necessary to explain a point about a code. Comments cannot be nestedin C i.e. you

cannot have comments inside comments.


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C program/* Example program in C*/ Comments

# include Preprocessor Section

Global Declaration

void main ()

{ Local declaration

printf (Hello World! \n); Statements

}

Output :

Hello World


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C Tokens

Identifiers

Keywords

Constants Operators

Special symbols


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Identifiers

Identifiers are names given to variousprogram elements such as variables,functions and arrays etc,.

Eg: #define N 10

#define a 15

Here N and a are user defined identifiers.


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Rules for naming identifier First character must be alphabetic or

underscore.

Must consist only of alphabetic characters,digits, or underscores.

Only the first 31 characters of an identifier aresignificant and are recognized by the compiler.

Cannot use a keywordsorreserved word(e.g.main, include, printf & scanf etc.).

No space are allowed between the identifiersetc,.

C is case sensitive, e.g. My_name my_name.


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Examples of Valid and Invalid Names

Valid Names Invalid Names

a a1 $sum /* $ is illegal */

student_name stdntNm 2names /* Starts with 2 */

_aSystemName _anthrSysNm stdnt Nmbr /* no spaces */

TRUE FALSE int /* reserved word */


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Variables

Variable is an identifier that is used torepresent some specified type ofinformation.

Eg: x=3

Here x is variable.


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Keywords

It is a reserved words.

Cannot be used for anything else.

Examples: int

while

for etc,.


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Keywords

Auto register Continue

Double typedef For

Int Char signed

Struct extern void

Break return Default

Else union Goto

Long Const sizeof

Switch Float do

Case short If

Enum unsigned

Static While


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Constants

It is an entity whose value does notchanges during the execution.

Eg: x=3

Here 3 is a constant.


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Types

Numeric constants

Character constant


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Constants

Constants

Character ConstantsNumeric Constants

RealConstant

IntegerConstant

StringConstant

SingleCharacterConstant


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Numeric constantsInteger constants

It is formed using a sequence of digits.

Decimal - 0 to 9 .

Octal - 0 to 7.

Hexa - 0 to 9 ,A to F

Eg: 10,75 etc.


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Rules for defining Integer Constant

It must have atleast one digit.

Decimal point are not allowed.

No blank space or commas are allowed. It can be either positive or negative. Etc,.


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Numeric constants

Real constants

It is formed using a sequence of digits butit contain decimal point.

length, height, price distance measured inreal number

Eg: 2.5, 5.11, etc.


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Character constants

Single character constant

A character constant is a single characterthey also represented with single digit or a

single special symbol which is enclosed insingle quotes.

Eg: a, 8,_etc.


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Character constants

String constants

String constant are sequence of charactersenclosed with in double quote.

Eg: Hello ,444,a etc,.


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Operators

An operator is a symbol that specifies anoperation to be performed on theoperands.

Eg: a + b

+ is an operator.

a,b are operands.


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Data Types

A Data typeis the type of data that aregoing to access within the program.


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StandardData Types

These Standard type can be used to buildmore complex data types calledDerived

Types (e.g. pointers, array, union etc.).

D t t


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Data types

Data type Size(bytes) Range Format string

Char 1 -128 to 127 %c

int 2 -32,768 to 32,767 %d

Float 4 3.4 e-38 to 3.4 e+38 %f

Double 8 1.7 e-308 to 1.7 e+308 %lf


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integer

A number without a fraction part : integralnumber.

C supports three different sizes of theinteger data type :

shortint int

longint


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Floating Point

A floating-point type is a number with afractional part, e.g. 56.78

Floating point numbers are stored using

4 Byte. Types

Float

Double long double


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character - PLato

Character are generally stored using 8bits(1 Byte) of the internal storage.

Character ASCII code value

a 97(decimal) or 01100001(binary)

x 120(decimal) or 01111000(binary)


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void

The void type has no values and nooperations.

Both the set of values and the set ofoperations are empty.


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Variables Declaration

To create a variable, you must specifythe type and then its identifier :

float price;int a,b;

char code;

E ti D t t i


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Entire Data types in c:

Data type Size(bytes) Range Format string

Char 1 128 to 127 %c

Unsigned char 1 0 to 255 %c

Short or int 2 -32,768 to 32,767 %i or %d

Unsigned int 2 0 to 65535 %u

Long 4 -2147483648 to 2147483647 %ld

Unsigned long 4 0 to 4294967295 %lu

Float 4 3.4 e-38 to 3.4 e+38 %f or %g

Double 8 1.7 e-308 to 1.7 e+308 %lf

Long Double 10 3.4 e-4932 to 1.1 e+4932 %lf


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Types of Operator

Arithmetic operator

Relational operator

Logical operator

Assignment operator

Increment or decrement operator(unary)

Bitwise operator Conditional operator


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Arithmetic operator

It is used to carry out arithmeticoperations like addition, subtraction etc,

Eg: + , - , * , / etc,


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Sample program

#include // Header File#include int b=10; //Global Declarationvoid main ( ) /* main is the starting of every c program */{int a,c; //Local Declarationclrscr( );scanf(%d,&a);printf( \n The sum of the two values:);

c = a+b;printf(%d,c);getch( );}

Di i i t Diff t


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Division operator on DifferentData Type

Operation Result Example

int/int int 5/2 = 2

int/real real 5/2.0 = 2.5

real/int real 5.0/2 = 2.5

real/real real 5.0/2.0 = 2.5

Sample program


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Sample program

#include

#include void main ( ){int a=10,b=4,c;

float d=3,e;clrscr( );c = a/b;printf(" \n value a/b is:%d",c);e = a/d;printf("\n value a/d is:%f",e);getch( );

}


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Output

value a/b is:2

value a/d is:3.333333


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Relational operator

It is used to compare two or moreoperands.

Eg :< , > , =, != etc,.

5 < 9 which will return 1


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Logical operator

It is used to combine the result of two ormore condition.

AND(&&)

OR (||)

NOT (!) are Logical operators.

Eg: (i>10)&&(j>5).(i>10)||(j>5) etc,.

Sample program


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Sample program#include#include

void main ( ){int a=10,b=3,c=5,e;clrscr( );

if(a>b) // relational operator{

printf(" \n a is bigger than b");}if((a>b)&&(a>c)) //Logical operator

{printf(" \n a is biggest");

}getch( );

}


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Output

a is bigger than b

a is biggest


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Assignment operator

It is used to assign a value orexpression etc to a variable.

Eg: a =10.

a = b

a = b + c etc,.


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Assignment operator(Cont)

Compound operator

It is also used to assign a value to avariable.

Eg: x + = y means x = x + y

Nested operator

It is used for multiple assignment.Eg: i = j = k = 0;


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Sample program#include

#include int b=10;

void main ( )

{int a=3,b=5;

clrscr( );

a+=b; // a= a+b

printf(" \n The sum of the two values:%d",a);

getch( );

}


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Output

The sum of the two values:8

Increment or decrement


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Increment or decrementoperator(Unary)

It is used to Increment or decrement anoperand.

Eg: ++x (Pre Increment),

x++ (Post Increment),

--x (Pre Decrement),x-- (Post Decrement).

Sample Program


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Sample Program#include

#include void main ( )

{

int a=5;clrscr( );

printf(" \n Post increment Value:%d",a++);

printf(" \n Pre increment Value:%d",++a);printf(" \n Pre decrement Value:%d",--a);

printf(" \n Post decrement Value:%d",a--);

getch( );


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Output

Post increment Value:5

Pre increment Value:7

Pre decrement Value:6

Post decrement Value:6


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Bitwise operator

It is used to manipulate data at bit level.

Eg: a=5 i.e 0000 0101

b=4 i.e 0000 0100

Then a & b = 0000 0100

a | b = 0000 0101 etc,.

Sample program


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Sample program

#include

#include void main ( ){

int a=5,b=4,c;//char a=5,b=4,c;clrscr( );

c = a&b;printf(" \n value a&b is:%d",c);getch( );}


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Output

value a&b is:4

Conditional Operator (or)


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Conditional Operator (or)Ternary Operator

It is used to checks the condition andexecute the statement depending on thecondition.

Eg: C = a > b ? a:b

Sample Program


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#include void main ( )

{

int a=5,b=8,c;

clrscr( );

c = a>b?a:b; //Conditional operator

printf(" \n The Larger Value is%d",c);

getch( );

}


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Output

The Larger Value is 8


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Special Operator

comma operator ( , )

sizeof operator

pointer operator (& , *) etc,.


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#include#include

void main ( )

{int c;

clrscr( );

printf(" \n size of int is:%d",sizeof c);

getch( );

}


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Output

size of int is: 2


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Expression

An expression represent data item such asvariable, constant are interconnectedusing operators.

Eg:

Expression C Expression

a + b + c a + b + c

a2+b2 a*a + b*b


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Operator Precedence & Associativity

The arithmetic expressions evaluation arecarried out based on the precedence andassociativity.

The evaluation are carried in two phases. First Phase: High Priority operators are

evaluated.

Second Phase: Low Priority operators areevaluated.


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Precedence Operator

High * , / , %

Low + , -


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Example

5 - 20/4 + 3*3 1

= 5 - 5 + 9 1

= 0 + 9 1

= 9 1

= 8


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Example

5 (20/4) + 3*(3 1)

= 5 - 5 + 3*2

= 5 - 5 + 6

= 6

T C i


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Type Conversion

Converting the type of an expression fromone type to another type.

Eg: x = (int)10.45

Sample Program


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#include void main ( ){int c;

clrscr( );c=(int)10.45;printf("\nOutput is:%d",c);getch( );}OUTPUTOutput is:10

I t/O t t F ti


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Input/Output Function

Input/OutputFunction

UnformattedFormatted

Output

printf()fprintf()

Input

scanf()fscanf()

Input

getc()gets()

getchar()

Output

putc()puts()

putchar()


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Formatted Input/Output

C uses two functions forformattedinput and output.

Formatted input : reads formatteddata from the keyboard.

Formatted output : writes formatteddata to the monitor.


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FormattedInput and Output


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Standard Output

The standard output file is the monitor.

Like the keyboard, it is a textfile.

When you need to display data that is

not text, it must be converted into to the

text before it is written to the screen.

F t f i tf St t t


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Format of printf Statement

F tt d I t ( f)


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Formatted Input (scanf)

The standard formatted input function in C isscanf(scan formatted).

scanfconsists of : a format string .

an address list that identifies where dataare to be placed in memory.

scanf ( format string, address list );

(%c.%d..%f.., &a,.&i,..,&x..)

Format of scanf Statement


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Format of scanf Statement

Ch t T t F ti


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Character Test Function

It is used to test the character taken fromthe input.

isalpha(ch)

isdigit(ch) islower(ch)

isupper(ch)

tolower(ch) toupper(ch) etc,.


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D i i M ki


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Decision Making

It is used to change the order of theprogram based on condition.

Categories:

Sequential structure

Selection structure

Iteration structure

Encapsulation structure

Decision Making (cont)


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Decision Making (cont)

Sequential structure

In which instructions are executed insequence.

Selection structure

In which instruction are executed based onthe result of some condition.

Iteration structure

In which instruction are executed repeatedly. Encapsulation structure

In which some compound structure are used.

SELECTION STRUCTURE


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SELECTION STRUCTURE

It allows the program to make a choicefrom alternative paths.

C provide the following selection

structures IF statement

IF ELSE statement

Nested IF ELSE statement IF ELSE ladder

IF Statement


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IF Statement

SyntaxIF (condition is true)

{

Statements;

}

Ifcondition

False

True

Statements

Example


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Example#include#include

void main ( ){int a;clrscr( );printf("\nEnter the number:");scanf("%d",&a);

if(a>10)

{ printf(" \n a is greater than 10");}

getch( );

}

Output


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Output

Enter the number: 12

a is greater than 10

IFELSE Statement


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IFELSE Statement

Syntax

IF (condition)

{

True statements;

}ELSE

{

False statements;

}

IfCondition

True False

Truestatements

Falsestatements

#include#include


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#include void main ( ){

int a;clrscr( );printf("\nEnter the number:");scanf("%d",&a);

if(a>10){printf(" \n a is greater than 10");

}else

{printf(" \n a is less than 10");

}getch( );

}

NESTED IF ELSE


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NESTED IF ELSE

IfCondition

2

True False

Truestatements

Falsestatements

IfCondition

1False

StatementsTrue


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IF ELSE LADDER


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IFELSE LADDER

Condition1

Statements

Condition

2

Statements

Condition3

Statements Statements

TRUE

TRUE

TRUE FALSE

FALSE

FALSE

IFELSE LADDERSyntax


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yIF (condition1){

statements;}

else if (condition2){

statements;}else if (condition3){statements;

}else{statements;

}

Example


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Example#include#includevoid main(){int m1,m2,m3;float avg;

printf("\nEnter the marks:");scanf("%d%d%d",&m1,&m2,&m3);avg=(m1+m2+m3)/3;printf("\n The average is:%f",avg);

printf("\n The Grade is:");if(avg>=60){

printf("First class");}


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Output


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Output

Enter the marks:65

75

70The average is:70.000000

The Grade is: First class

Looping structure


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Looping structure

It is used to execute some instructionsseveral time based on some condition.

WHILE

DoWHILE For

WHILE Loop


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WHILE Loop

Syntax.

WHILE (condition)

{ .Body of the loop;

.} Body of The loop

conditionFalse

True

Example


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Example#include

#includevoid main(){int i=1,fact=1,n;printf("\nEnter the Number:");scanf("%d",&n);

while(i


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Output

Enter the Number:3

The value of 3! is: 6

DO WHILE Loop


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DOWHILE Loop

Syntaxdo

{

Body of the loop

}while (condition);

Body of The loop

condition

False

True

for loop


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for loop

Syntaxfor (initialization; test condition; Increment/Decrement)

{

Body of the loop

}

for loop


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for loop

Initialization

condition False

Body of the loop

Inc / Decrement

Example


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Example#include

#includevoid main(){int i,fact=1,n;printf("\nEnter the Number:");scanf("%d",&n);

for(i=1;i


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Output

Enter the Number:3

The value of 3! is: 6

Nested for loop


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Nested for loop

Syntaxfor (initi; cond; Inc/Dec)

{

for (initi; cond; Inc/Dec){

Body of the loop

}

}

CASE structure


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Case 1

Case 2

Default

case

Switch

CASE structureSyntax


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Syntaxswitch (expression)

{case constant 1:block1;break;

case constant 2:block2;break;..

default :default block;break;

}

Example


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Example#include

#includevoid main(){int i,n;printf("\nEnter the Number:");

scanf("%d",&n);

switch(n){

case 1: {printf("\n Its in case 1");break;}


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case 2:

{printf("\n Its in case 2");break;}

default: {printf("\n Its in default");break;}

}getch();}

Output


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Output

Enter the Number:2

Its in case 2

break Statement


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break Statement

It is used to terminate the loop When a breakstatement is encountered

inside a loop, then the loop is terminated.

Loops with break Statement


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Loops with break Statement

while(cond){

if(cond)

break;

}


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do{

if(cond)

break;

} while(cond);


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for (initi; condt; Inc/Dec){

if(cond)

break;

}

Continue Statement


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Continue Statement

When a continue statement isencountered inside a loop, the control istransferred to the beginning.

Loops with continue Statement


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oops co ue S a e e

while(cond){

if(cond)

continue;

}


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do{

if(cond)

continue;

} while(cond);


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for (initi; condt; Inc/Dec){

if(cond)

continue;

}

goto Statement


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g

When a gotostatement is encounteredinside a loop, the control is transferred tothe beginning.

Syntax for goto Statement


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y g

label:

goto label;


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goto label;

label:


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getchar() Example


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g () p

#include#include

#include

void main()

{

char x;

printf("enter the character:");

x=getchar();

if(islower(x))


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( s o e ( ))

putchar(toupper(x));

else

putchar(tolower(x));

getch();}

Output:enter the character:ABC

a

getche() Example


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g () p

#include #include

void main()

{

char c ;

clrscr();

printf("\nInput a string:");

c = getche();


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printf("\nstring is:");putch(c);

getch();

}

Output:

Input a string:k

string is:k


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printf("\nstring is:");putch(c);

getch();

}

Output:

Input a string:

string is:h

getc Example


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#include#include

#include

void main()

{

char x;

printf("enter the character:");

x=getc(stdin);

if(islower(x))


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putc(toupper(x),stdout);

else

putc(tolower(x),stdout);

getch();

}

Output:enter the character:abc

A

gets() Example


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#include #include

void main()

{

char c[80];

clrscr();

printf("Input a string:");

gets(c);


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Example#include


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#include#includevoid main(){

int a,b,c,n;

clrscr();printf("\nEnter the value of a,b:");scanf("%d%d",&a,&b);printf("\nMENU");

printf("\n1.ADD\n2.SUB\n3.MULTIPLY\n0.EXIT");printf("\nEnter the choice:");scanf("%d",&n);

switch(n){


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{case 1:

c=a+b;printf("\nThe result of Addition is:%d",c);break;

case 2:c=a-b;printf("\nThe result of Subtraction is:%d",c);

break;


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case 3: c=a*b;printf("\nThe result of Multiplication is:%d",c);break;

case 0:exit(0);break;

}

getch();}


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if(a==sum){printf("\nIt is an armstrong number");

}

else{printf("\nIt is not an armstrong number");

}

getch();}

Output


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Enter the number:153It is an armstrong number

Sum of the Digits


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#include#includevoid main(){

int r=0,sum=0,n;printf("\nEnter the no:");scanf("%d",&n);while(n>0)

{r=n%10;


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Output


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Enter the no:156sum of the digits is:12

Reverse of a number


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#include#include

void main()

{

int r=0,sum=0,n;

printf("\nEnter the no:");

scanf("%d",&n);

while(n>0)


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{r=n%10;

sum=sum*10+r;

n=n/10;}

printf("Reverse of the number is:%d",sum);

getch();}

Output


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Enter the no:567Reverse of the number is:765

Fibonacci Series


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#include#include

void main()

{

int f=0,f1=-1,f2=1,n,i;

printf("\nEnter the number:");

scanf("%d",&n);


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while(f


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Enter the number:50 1 1 2 3 5

Swapping#include


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#include stdio.h#include void main ( ){int a,b,c;

clrscr( );printf(" \nEnter the value of a:");scanf("%d",&a);printf(" \nEnter the value of b:");

scanf("%d",&b);c=a;a=b;b=c;

printf(" \nThe value of a is:%d",a);


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printf(" \nThe value of b is:%d",b);

getch( );

}

Output:Enter the value of a:5

Enter the value of b:4

The value of a is:4

The value of b is:5

Swapping without using thirdvariable


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#include#include void main ( ){

int a,b;clrscr( );printf(" \nEnter the value of a:");scanf("%d",&a);

printf(" \nEnter the value of b:");scanf("%d",&b);

a=a+b;

b=a-b;

b


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a=a-b;

printf(" \nThe value of a is:%d",a);printf(" \nThe value of b is:%d",b);

getch( );

}

Output:

Enter the value of a:5


The value of a is:6

The value of b is:5

Quadratic Equation#include


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#include

#includevoid main ( ){int a,b,c,d,r1,r2;clrscr( );printf(" \nEnter the value of a:");scanf("%d",&a);printf(" \nEnter the value of b:");scanf("%d",&b);

printf(" \nEnter the value of c:");scanf("%d",&c);d=b*b-4*a*c;

if(d>=0)


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{

r1=(-b+sqrt(d))/(2*a);r2=(-b-sqrt(d))/(2*a);

printf(" \nThe roots are %d,%d",r1,r2);}else{printf(" \nThe roots are imaginary");}

getch( );}

Output


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Enter the value of a:4


Enter the value of c:6

The roots are imaginary

Introducion to C Programming

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