c lang for learners

8/8/2019 C Lang for Learners

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REVIEW OF C


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Programming language category

1. Problemorientedor Highlevellanguage:

Better programming efficiency

Faster program development

FORTRAN,BASIC,PASCAL

Machineorientedor Lowlevellanguages Better machine efficiency

faster program execution

Assembly language & machine language


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C is Middle level language

Relativelygood

programmingefficiency

Relativelygood

machineefficiency


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VARIABLES

Avariablenameisanycombinationof1to 8 alphabets,digitsor

Underscores

Thefirstcharacterinthevariablenamemustbeanalphabet

Nocommasorblanksareallowedwithinavariablename.

Nospecialsymbolotherthananunderscorecanbeusedina

variablename.

Rules for constructing variables


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SCOPEOFVARIABLES

LOCAL

GLOBAL

Availabilitywithinafunction

Availabilityoutsideafunction


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C DATATYPES

PRIMARY DATATYPES SECONDARY DATATYPES

Character

Integer

Float

Double

Void

Array

Pointer

Structure

Union

Enum


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STORAGECLASS

AUTOMATIC REGISTER STATIC EXTERN


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AUTOMATIC

Storage: memory

Default initial value: garbage value

Scope : local

Life : within the block in which it is defined


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REGISTER

Storage: CPU registers

Default initial value: garbage value

Scope : local

Life : within the block in which it is

defined


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STATIC

Storage: memory

Default initial value: zero

Scope : local

Life : value of the variable persists betweendifferent function calls.


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EXTERN

Storage: memory

Default initial value:zero

Scope : global

Life : as long as the programs executiondoesnt come to an end.


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OPERATORS

ARITHMATIC

INCREMENT & DECREMENT

MODULO DIVISION

RELATIONAL

LOGICAL BITWISE

CONDITIONAL

ASSIGNMENT


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MEMORY MAP OFANARRAY

3 4 5 6

a[0] a[1] a[2] a[3]

SINGLE DIMENSIONARRAY

100 102 104 106


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DOUBLE DIMENSIONARRAY

C A L C U T T A \0

D E L H I \0

M U M B A I \0

C H E N N A I \0

R[0]

R[1]

R[2]

R[3]

C[0] C[1] C[2] C[3] C[4] C[5] C[6] C[7] C[8]

STRING1

STRING2

STRING3

STRING4


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PONTERS

THE & AND * OPERATORS

15

a

1002

Location name

Value at

location

address


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ONTER ASSIGNMENT

int *p; int a=15;

p= &a;

15

a

1002

1002

p


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USING POINTERWITHARRAYS

3 4 5 6

a[0] a[1] a[2] a[3]

100 102 104 106

P

a[1] represents(a+1) i.e 102

*(a+1)=4 eqv. to *p

int *p


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POINTERTOARRAY

*P

p = (int *)malloc(sizeof(int[10]));

for (i=0; i


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POINTERTO POINTER

15

int **p, * q ; int a=15;

**p=a; q= *p

*p

**p *q

q

p


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main()

{char temp[20]= KOLKATA;

char *s=KOLKATA;

s++;

temp++;

printf(%s%s,s,temp);

}


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main()

{int b[]={10,20,30,40,50};int i,*k;

k=&b[4]-4;

for(i=0;i


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main()

{int a[]={2,4,6,8.10};

int i;

for(i=0;i


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main()

{int a[]={2,4,6,8,10};

int i,b=5;

for(i=0;i


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main()

{

intarr[]={0,1,2,3,4 };

inti,*ptr;

for(ptr=&arr[0] ; ptr


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main()

{

intarr[]={0,1,2,3,4 };

inti,*p;

for(p=arr,i=0 ; p+i


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int a[ ] = {0,1,2,3,4};

int *p[ ]={a,a+1,a+2,a+3,a+4};

int **ptr=p;

printf( %d%d\n,a,*a);

printf( %d%d %d \n,p,*p,**p);

printf( %d%d %d \n,ptr,*ptr,**ptr);


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main()

{ int a[ ]={0,1,2,3,4};

int *p[ ]={a,a+1,a+2,a+3,a+4};

int **ptr ;

ptr=p;

**ptr++;

printf(%d%d%d, ptr-p, *ptr-a, **ptr);

*++*ptr;

printf(%d%d%d, ptr-p, *ptr-a, **ptr);

++**ptr ;

rintf %d%d%d, tr- , * tr-a, ** tr ;


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main( )

{ int n[3][3] = {2,4,3

6,8,5

3,5,1 };

int *ptr= n;

printf(%d,*(ptr+2));

printf(%d,(*(*(n+1)+2));

.


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POINTERTOFUNCTION

A function has a physical location in memory that can be

assigned to a pointer.this is an entry point of the function& it is the address used when the function is called.

int(*cmp)(const char*,const char*);


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POINTERTOFUNCTION

intmain()

{chars1[80],s2[80];

int(*p)(constchar*,constchar*);

p=strcmp;

gets(s1);gets(s2);

check(s1,s2,p);

}

voidcheck(char*a,char*b,int(*cmp)(constchar*,constchar*))

{ if(!(*cmp)(a,b)) printf(equal);

else printf(notequal);}


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STRUCTURESAND UNIONS

structure contains heterogeneous data types.

ifferent variables are stored at different places in memory .

nions are derived data types like structures.

nion enables to treat the same space in memory as a

umber of different variables


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ARRAY OF STRUCTURES

struct student

{ char name[20];

int marks;

};

Struct student st [20]; Keeps record of 20 students


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STRUCTURE POINTERS

name

marks

*st

struct student

{ char name[20];

int marks;

};

Struct student *st;


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SELFREFERENTIALSTRUCTURE

struct student

{ char name[20];

int marks;

struct student *std;

};


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DATASTRUCTURE

Show how data structures are represented in the computer

Identify linear and nonlinear data structures .

Manipulate data structures with basic operations

Compare different implementations of the same data

structure


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TYPESOF DATASTRUCTURE

ARRAYS

LINKLIST

STACK

QUEUE

TREES

GRAPH


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DATASTRUCTUREOPERATIONS

SIXOPERATIONS PLAYA MAJORROLE

1.TRAVERSING:accessing & processingeach record exactly

once.

2.SEARCHING:Findingthelocation ofall records whichsatisfy

one or moreconditions.

3.INSERTING:addinganew record to thestructure.

4.DELETING:removinga record from thestructure.

5.SORTING: arrangingthe recordsinsomelogical.

6.MERGING:combiningthe recordsintwo differentsorted files

into asinglesorted file.


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LINKLIST

CUSTOMER SALESMAN

Adams

Brown

Clerk

Farmer

Hill

Jones

Smith

Ray

Jones

Jones

1

2

3

4

5

CUSTOMERPOINTER

Adams

Brown

Clerk

Farmer

Hill

1

2

3

1

1

1

2

3

4

5


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SALESMAN PONTER

JONES1,4,5

Theset of pointers will changeas customersareadded & deleted

(dangling pointer)


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customer pointer

Adams

Brown

Clerk

Farmer

Hill

Sales person pointer

JONES 1

4

5

0

Keepstheaddressof

firstpointedrecord


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CIRCULARLINK LIST

A linked list whose last node points back to the first node

instead of containing the null pointer,called a circular list .

HEADERLINK LIST

It is a linked list which always contains a special

node,called header node,at the beginning of the list.

1.Agrounded header list is a list where the last nodecontains the null pointer.

2. Acircular header list is a list where the last node points

back to the header node.


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DOUBLELINK LIST

A linked list, each node having two pointers left & right

to point previous & next nodes respectively.


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AVAILABLESPACE

A special list is maintained which consists of unused

memory cells. This list,which has its own pointer,is called

the list of available space or the free-storage list or free

pool.

GARBAGECOLLETION

The operating system of a computer may periodically

collect all the deleted space onto the free-storage list.The

technique which does this collection is called garbage

collection.


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problems

Model

abstraction

ABSTRACT DATATYPES


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Abstract data structure

operations

interface

PROPERTIESABSTRACT DATATYPES


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STACK

PROPERTIES:elementsmaybeinsertedordeletedonlyatone

end,calledtopofthestack(LIFO order).

BASIC OPERATIONS:

PUSH : insertanelementintoastack.

POP: deleteanelementfromstack.

1 2 3 4 5 6 7

AAA BBB CCC

TOP 3 MAX 7


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POLISH (INFIX)TO REVERSE POLISH (POSTFIX)

CONVERSION

1.insert (intostack )attheendoftheinfixexpression.

2.scantheexpressionfromlefttoright&repeatstep3to 6 until

stackisempty.

3. Ifanoperandisencounteredthenwritethatoperandontothe

postfixstring.

4. Ifa( isencounteredthenpushitontostack.

5.ifanoperatorisencounteredthenrepeatedlypopfromstackthoseoperatorswhoseprecedenceisgreaterorequaltothe

precedenceofencounteredoperatorsandwritethemonthe

postfixstring.

6.if)isencounteredthenrepeatedlypopfromstack&writethem


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INFIX TO PREFIX CONVERSION

1.insert )intostack (attheendoftheinfixexpression.

2.scantheexpressionfromrighttoleft&repeatstep3to 6 until

stackisempty.

3. Ifanoperandisencounteredthenwritethatoperandontotheprefixstring.

4. Ifa) isencounteredthenpushitontostack.

5.ifanoperatorisencounteredthenrepeatedlypopfromstack

thoseoperatorswhoseprecedenceisgreaterorequaltothe

precedenceofencounteredoperatorsandwritethemonthe

postfixstring.

6.if(isencounteredthenrepeatedlypopfromstack&writethem

onthepostfixexpressionuntilthe ) isencountered.


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EVALUATIONOFA POSTFIXEXPRESSION

1.insert # attheendofthepostfixexpression.

2.scanpostfixexpressionfromlefttorightandrepeatstep3to4

until # isencountered.

3. Ifanoperandisencounteredthenpushitontostack.

4.ifanoperatorisencounteredthenpopthetopelement&nextto

topelementandperformoperationwithencountered

operation.pushresultontothestack.

5.topelementofthestackgivestheresultofthepostfixexpression.


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EVALUATIONOFA PREFIXEXPRESSION

1.insert # atthebeginning oftheprefixexpression.

2.scanprefixexpressionfromrighttoleft andrepeatstep3to4

until # isencountered.

3. Ifanoperandisencounteredthenpushitontostack.

4.ifanoperatorisencounteredthenpopthetopelement&nextto

topelementandperformoperationwithencountered

operation.pushresultontothestack.

5.topelementofthestackgivestheresultoftheprefixexpression.


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QUEUE

PROPERTIES:elementsmaybeinsertedonlyatoneend&

deletedonlyattheotherend (FIFO order).

BASIC OPERATIONS:

REAR : insertanelementintoastructure.

FRONT : deleteanelementfromstack.

1 2 3 4 5 6

AAA BBB CCCREAR : 3

FRONT :1


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DEQUEUE

linearlistinwhichelementscanbeaddedorremovedateither

ndbutnotinmiddle.

equeismaintainedbyacirculararraywithpointers LEFT&IGHT,whichpointtothetwoendsofthequeue.

Twovariations ofdeque:

Inputrestricteddeque: whichallowsinsertionsatonlyoneendofthelistbutallowsdeletionsatbothendsofthelist.

Outputrestricteddeque:whichallowsdeletionsatonlyoneend

ofthelistbutallowsinsertionsatbothendsof thelist.


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AAA BBBLEFT : 3

RIGHT:4

1 2 3 4 5

1 2 3 4 5

BBB CCCDDDLEFT : 4

RIGHT:1


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