Introduction to Data Structures 17022012

8/13/2019 Introduction to Data Structures 17022012

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Introduction to Data Structures

CMPE231 Spring 2012

Assoc. Prof. Alexander Chefranov

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Information and Meaning

Concept of information similar to the concept

of point, line, and plane in geometry is not

defined formally

It is possible to talk about the length of a line

We can measure quantities of information

The basic unit of information is the bit

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Binary and Decimal Numbers

Binary number system

Ones complement notation

Twos complement notation Binary coded decimal

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Real Numbers

Floating-point notation

Mantissa

Base Exponent

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Data Type

Integer

Real number

Character string Memory, Address, Value (Contents)

Int x,y;

Float a,b;

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Character Strings

Byte

First byte size

Null terminating strings

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Abstract Data Types

/*value definition*/

Abstract typedef RATIONAL;

Condition Rational[1]!=0;

/*operator definition*/

Abstract RATIONAL makerational(a,b)

Int a,b;

Precondition b!=0;

Postcondition makerational[0]==a; makerational[1]=b;

Abstract RATIONAL add(a,b) /*written a+b */

RATIONAL a,b;

Postcondition add[1]==a[0]*b[0];

Add[0]==a[0]*b[1]+a[1]*b[0];

Abstract RATIONAL mult(a,b) /*written a*b */

RATIONAL a,b;

Postcondition mult[0]==a[0]*b[0]; mult[1]==a[1]*b[1];

Abstract equal(a,b) /*written a==b */

RATIONAL a,b;

Postcondition equal==(a[0]*b[1]==a[1]*b[0]);

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Sequences as Value Definitions

S=

Abstract typedef stp1;

Abstract typedef stp2; Abstract typedef stp3;

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ADT for Varying-length Character

Strings Abstract typedef STRING;

Abstract length(s)

STRING s;

Postcondition length==lens(s);

Abstract STRING concat(s1,s2)

STRING s1,s2;

Postcondition concat==s1+s2;

Abstract STRING substr(s1,i,j)

STRING s1;

Int I,j;

Precondition 0


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Data Types in C

Int, float, char, double

Short int, long int, unsigned

Pointers

Int *pi;

Float *pf;Char *pc;

Pi=(int *)pf;

Int x;

Pi=&x; x=*pi;*(pi+1)

*pi+1

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Parameters

By value, by reference

1 x=5;

2 printf(%d\n,x);

3 funct(x);

4 printf(%d\n,x);

..

5 void funct(int y){

6 ++y;7 printf(%d\n,y);

8 }

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Parameters (cont)

1 x=5;

2 printf(%d\n,x);

3 funct(&x);

4 printf(%d\n,x);

5 void funct(int *py){

6 ++(*py);

7 printf(%d\n,py);

8 }

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Arrays in C

One-dimensional array

Int a[100];

Basic operations: extracting and storingLower bound, Upper bound

#define NUMELTS 100

Int a[NUMELTS];For(int i=0;i


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The Array as an ADT

Abstract typedef ARRTYPE(ub,eltype);

Condition type(ub)==int;

Abstract eltype extract(a,i) /* written a[i] */

ARRTYPE(ub, Eltype) a;

Int I;Precondition 0


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Using One-Dimensional Arrays

#define NUMELTS 100

Void main(){

Int num[NUMELTS];

Int I;

Int total;

Float avg;

Float diff;

Total=0;

For(i=0;i


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Implementing One-Dimensional Arrays

Int b[100];

Base address

B[i] in base(b)+i*esize

In C an array variable is a pointer variable

Int *b does not reserve 100 elements

B+I; *(b+i)

Varying-sized element array: reserve a contiguousset of memory locations each of which holds anaddress of an element

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Arrays as Parameters

Float avg(float a[], int size){

int I;

Float sum;

sum=0;

for(i=0;i


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Character Strings in C

#define STRSIZE 80

Char string[STRSIZE];

Int Strlen(char string[]){

int I;

for(i=0;string[i+!=\0;i);

return I;

}

Int strpos(char s1[],char s2[]){

int len1, len2, I,j1,j2;

len1=strlen(s1);

len2=strlen(s2);

for(i=0;i+len2


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Character Strings in C (cont)

Void strcat(char s1[], char s2[]){

int I,j;

for(i=0;s1[i+!=\0;i);

for(j=0;s2*j+!=\0;s1*i++]=s2[j++];

}

Void substr(char s1[],int I, int j, char s2[]){

int k,n;

for(k=I,m=0;m


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Two-Dimensional Arrays

Int a[3][5];

Range r1 of the 1stdimension (rows) is 3

Range r2 of the 2

nd

dimension (columns) is 5A[1][3]=5;

Base(ar)+(i1*r2+i2)*esize

5

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Multi-Dimensional Arrays

Int b[3][2][4];

Base(ar)+esize*(i1*r2*..*rn+i2*r3*..*rn+..+i(n-

1)*rn+in)0 2

0 1

0 3

B[0][0][0]

B[0][0][1]

B[0][0][2]B[0][0][3]

B[0][1][0]

B[0][1][1]

B[0][1][2]

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Structures in C

Struct{

char first[10];

char midinit;

char last[20];

} sname, ename;

Typedef struct{

char first[10];

char midinit;

char last[20];

} NAMETYPE;

NAMETYPE sname, ename;

struct nametype{

char first[10];

char midinit;

char last[20];

}Struct nametype sname, ename;

Printf(%s,sname.first);

Ename.midinit=N;

For(i=0;i


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Unions

#define LIFE 1

#define AUTO 2

#define HOME 3

Struct addr{

char street[50];

char city[10];

char state[3];

char zip[6];}

Struct date{

int month;

int day;

int year;

}

Struct policy{

int polnumber;

Char name[30];

struct addr address;

int amount;

Float premium;

Int kind; /*LIFE,AUTO,HOME*/

Union{

struct{

char beneficiary[30];

struct day birthday;

} life;

struct{int autodeduct;

Char license[10];

char state[3];

char model[15];

int year} auto;

Struct{

int homededuct;

int yearbuilt;

} home;

}policyinfo;

}

Struct policy p;

If(p.kind==LIFE)

printf(\n%s %2d %2d %4d,

p.policyinfo.life.beneficiary,

p.policyinfo.birthday.month,

p.policyinfo.life.birthday.day, p.

policyinfo.life.birthday.year);

Struct policy a[100];

For(i=0;i


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Structure Parameters

Int writename(struct nametype *name){

int count,I;

count=0; printf(\n);

for(i=0;(ifirst[i+!=\0);i++){

printf(%c,name->first[i]);

count++;

}

printf(%c, ); count;

if(name->midinit!= )

printf(%c%s, name->midinit,. ); count=3;

}

for(i=0;(ilast[i+)!=\0);i++){printf(%c,name->last[i]); count++;

}

return count;

}

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Allocation of Storage and Scope of

Variables

Automatic variables (declared within a function)

Can be referenced only throughout entire

block unless the variable identifier is

redeclared within an internal block

External variables (declared outside of any

function) The scope lasts from the point at

which it is declared until the end of itscontaining source file

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Allocation of Storage and Scope of

VariablesFile1 #define MAXSTUDENTS ..

int grades[MAXSTUDENTS];

End of file1

File2 extern int grades[];

Float average(){

..

}

End file2

Static variables

Register variablesUninitialized external and static variables are initialized to 0, whereas

uninitialized automatic and register variables have undefined values

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Source file1.c

1 int x,y,z;

2 void func1(){3 int a,b;

4 x=1; y=2;z=3;a=1;b=2;

5 printf(%d %d %d %d %d\n,x,y,z,a,b);

6}

7 void func2(){

8 int a=5;

9 printf(%d %d %d %d\n,x,y,z,a);10}

End of file1.c

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file2.c

11 #include

12 extern int x,y,z;

13 void main(){

14 func1();

15 printf(%d %d %d\n,x,y,z);

16 func2();

17 func3();

18 func3();

19 func4();


21}

22 Void func3(){

23 static int b;

24 y++; b++

25 printf(%d %d %d %d\n,x,y,z,b);

26}27 void func4(){

28 int x=10,y=20,z=30;


30}

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Dynamic Memory Allocation

Void *calloc(size_t nobj, size_t size)

Returns a pointer to space for an array of nobjobjects, each of size size, or NULL if the

request cannot be satisfied. The space isinitialized to zero bytes

Void *malloc(size_t size)

Returns a pointer to space for an object of sizesize, or NULL if the request cannot besatisfied. The space is uninitialized.

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Introduction to Data Structures 17022012

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