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C Programming and Data Structures May/June 2008 SET- 3 1. What are different types of control statements available in ‘C’. Explain them with an example ? Ans: Control statements are also called as decision making statements. They are 1. If statement 2. Switch and break statements 3. Conditional operator statement 4. Go to statement Let us discuss these statements in detail with examples. If Statement

If statement is a powerful decision making statement and is called to control the flow of execution of statements. It is implemented in different forms Simple If

General form:

if(expression) { Statements ; } Statements;

If expression false statements

statements

true

statements

C.40 Solved Question Papers Example: Main () { Int a,b,c,d; float ratio; printf(enter the values"); scanf("%d%d%d",&a,&b,&c); if(c-d!=0) { Ratio=(float(a+b)/float(c-d)); Printf("ratio=%f",ratio); } If Else Statement

General form: If(expression) { True block } Else { False block } Statements;

If expression

false

False block

true statements statements

Example: If(c-d!=0) { Ratio=float(a+b)/float(c-d); Printf("ratio=%f",ratio); } Else Printf("c-d is zero"); }

Solved Question Papers Nested or if Else Statement

General form: If(condition 1) { If(condition 2) { Statement 1; } Else { Statement 2; } Else { Statement 3; } Statement x;

In nested if else series if decisions are involved. It has more than one if else statements. false

Statement 3

true

If condition 1

Condition 2

Statement 2

Statement

Example: Main() { Float a,b,c; Printf("enter the values"); Scanf("%F%f%f",&a,&b,&c); Printf("largest value is"); If(a>b) { If(a>c)

Statement 1

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C.42 Solved Question Papers Printf("%f",a); Else Printf("%f",c); } Else { If(c>b) Printf("%f",c); Else Printf("%f",b); } } Else if Lader

General form: If(condition 1) Statement 1; Else if(condition 2) Statement 2; Else if(condition 3) Statement 3; Else if(condition n) Statement n; Else Default statement; Statements;

Here, the conditions are evaluated from the top document cards. Cond 1 Statement 1

Cond 2

Statement 2

Cond 3 Statement 3

Statements Next Statement

Example: Main() { Int units, custno;

Default statement

Solved Question Papers Float charges; Printf("enter custno and units"); Scanf("%d%d",&custno,&units); If(units<=200) Charges=0.5 units; Else if(units<=400) Charges =100+0..6s(units-200); Else if(units<=600) Charges=390+units-600; Printf("custno %d", charges =%f", custno,charges); }

Switch and Break Statements General form: Switch(expression) { Case 1: Statements; Break; Case 2 : Statements; Break; Default : Statements: Break; } Statements; Switch expression

Case1 no

yes

Block 1

yes Block 2

Case2 no Default

Statements

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C.44 Solved Question Papers Example: Switch(choice) { Case 1 ''+': C=a+b; Break; Case '-': C=a-b; Break; Default: Printf("operation not possible"); }

Conditional Operator Statement General form: Conditional expression ? expression 1: expression 2

Example: Flag(x<0) ? 0:1; Salary= 4x+100 for x<40 300 for x=40 4.5x+150 for x>40 The data can be written as Salary=(x!=40)?(x<40)?(4*x+100)L4.5*x+150):300;

Go to Statement

Go to requires a label in order to identify the place where the branch is to be made. A label is any valid variable name Example: Main () { Double Read:

x,y; Scanf("%f",&x); If(x<0) goto read; Y=sqrt(x); Printf("%f%f",x,y); Go to read;

}

2. (a) Write a brief note on auto and static storage classes? Ans: Variables in C language are not only data type but are also of storage class that provides information about their location and visibility. The storage class decides the portion of the program within which the variables are recognised.

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Example: int m; main () { Int I; Float balance; }

The variable m which has been declared before the main is called global variable. It can be used in all the functions in the program. It need not be declared in other functions. A global variable is also known as external variable. The variables I and balance are called local variables. They are visible only inside functions in which they are declared. ‘C’ provides a variety of storage class specifiers that can be used to declare explicitly the scope and lifetime of variables. The concept of scope and lifetime are important only in malfunctioning and multiple file programming. Four storage class specifiers are Auto, register, static, and extern. Auto: Local variable known only to the function in which if is declared, default is auto. Declaration: Auto int x; Auto variables have garbage values unless they are initialized explicitly. Static: Local variable which exists and retains its value even after the control is transferred to the calling function. Declaration: Static int x; Static and extern variables are initialized automatically to zero. (b) Write a short note on call by reference? Ans: Functions are of four types 1. with argument with return 2. no argument with return 3. with argument no return 4. no argument no return While using with arguments case, the arguments may be passed as direct values. Sometimes they are passed with their address. This type of passing address of variable is called call by reference. Using the pointers in function, we can pass the address of variables in the functions. Example: Main() { Int x,y; X=100;

C.46 Solved Question Papers Y=200; Printf("before exchange x:%d y: %d", x,y) ; Exchange(&x,&y); Printf("after exchange: x=%d y=%d",x,y); } Exchange(a,b) Int *a,*b; { Int t; T=*a; *a=*b; *b=t; }

3. What is an array? What are the different types of arrays? Explain. Ans: An array is a group of related data items that share a common name. All the elements should be of same data type. Different types of arrays are: 1. one-dimensional arrays 2. two-dimensional arrays 3. multi-dimensional arrays Let us discuss about them in detail. One-dimensional arrays

A list of items can be given one variable name using only one subscript and such a variable is called a single subscripted variable or a one-dimensional array. Accessing

Values can be initialized to arrays as three types (i) direct : N[0]=1 N[1]=2 N[2]=3

(ii) n[3]={0,1,2}; (iii) using for loop: for(i=0;i<3;i++) scanf("%d",&n[i]); n[4]= n[0]+n[2]; n[6]= n[i]+3;

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Declaration

General form is type variable name[size] Example: float height[50]; Program main() { Int I; Float x[10], value, total; Printf("enter 10 real no"); For(i=0;i<10;i++) { Scanf("%f", &value); X[i]=value; } Total=0.0; For(i=0;i<10;i++) Printf(""x[%2d]=%st",i+1,x[i]); Printf("total=%2f",total); }

Two-Dimensional Arrays Initializing

They have elements in rows and columns. Two-dimensional arrays may be initialized by following methods. N[2] [3]={0,0,0,1,1,1,}; N[2][3]={{0,0,0},{1,1,1}}; (OR) N[2][3]={ {0,0,0}, {1,1,1}, };

Declaration: Type array name[row size][column size]; Program /*To perform the matrix addition by using two-dimensional arrays */ Main () { Int a[50][50], b[50][50],c[100][100],I,j,k; Printf("enter the elements");

C.48 Solved Question Papers For(i=0;i<3;i++) For(j=0;j<3;j++) Scanf("%d",&a[i][j]); For(i=0;i<3;i++) For(j=0;j<3;j++) Scanf("%d",&b[i][j]); C[i][j]=0; For(i=0;i<3;i++) For(j=0;j<3;j++) { C[i][j]=a[i][j]+b[i][j]; Printf("\n"); } Printf("%d",c[i][j]); }

Multi-Dimensional Arrays Declaration

Type array name [s1] [s2]Â…..[sm]; Example: int survey[3][5][12]; Float table[5][4][3]; 4. Define structure and write the general format for declaring and accessing members? Ans: Structure can store data items in consequent memory locations. The advantage of structures is that the data items may be of different data types. Declaring structures: Struct student { Char name[20]; Int stno; };

(1)

Memory allocation is as follows: Struct tagname { Data type n1; Datatype n2; };

In the case of (1) no memory allocation is not done, only the structure is defined for allocating.

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Struct bokkbank { Char title[20]; Char author[15]; Int pages; Float price; }; Struct bokbankk bookk1,book2,bok3;

Tag name is optional. Giving values to members: The link between a member and a variable is established by using 'dot operator' or 'period operator'. Book1.pages=250; Book1.price=28.50;

Also initialized using scanf( ) statement Scanf("%s",book1.title); Scanf("%d",bok1.pages);

Structure initialization: Main () { Static struct { Int weight; Float height; } Student={60,180,75}; --------------------------------}

Also can be initialized as Main () { Struct st_record { Int weight; Float height; }; Static struct st_record st1={60,180,75}; Static struct st_record st2={53,170,60}; -------------------------

C.50 Solved Question Papers } (OR) Struct st_recrd { Int weight; Float height; } st1={60,180,75}; Main (0 { Static struct st_recrd st2={53,170,60}; -----------------------------}

Accessing members of structure: Structure members can be accessed by writing variable name.member Dot( . ) operator links structure variable to the data member. It is the highest precedence operator and associatively is left to right. Assigning values to structure:

One way is to assign values at the time of declarating structure variables. Struct person p1={"ravi", "21", "male", "student"}

Another way is to assign values to each member separately as shown below. Strcpy(p1.name, "ravi"); P1.age=21; Strcpy(p1.gender, "male"); Strcpy(p1.occupation, "student");

Here is an example demonstrating the structure with initialized values. /* structure with initialized values */ #include<stdio.h> #include<conio.h> Void main ( ) { Struct organization { bb Char name[20]; Char designation[20]; Int sal; }; Struct organization emp1={"ramu", "secretary", "8000"}; Struct organization emp2={"raju", "manager", "18000"};

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Printf("details of employee one =%c%c%d",emp1.name ,emp1.designation, emp1.sal); Printf("details of employee one =%c%c%d",emp2.name ,emp2.designation, emp2.sal); }

5. What is purpose of library function feof()? How is feof() utilized within a program that updates an unformatted data file. Explain. Ans: Feof ( ) is a library function which represents end of file. It is an error handling function. It gives the end of data in a file. The file pointer moves by one character position for every operation of getc or putc. The getc will return an end of file marker eof, when end of the file has been reached. Therefore, the reading should be terminated when eof is encountered. Program #include<stdio.h> Main() { FILE *f1; Char c; Printf("data input"); F1=fpen("input file", "w"); While(c=getchar()!=eof) Putc(,f1); Fclose(f1); Printf("data utput"); F1=fpen("input",: "r"); While(c=getc(f1)!=eof) Printf("%c",c); Fclose(f1); }

The file input is reopened for reading. The program then reads its context character by character and displays it on the screen. Reading is terminated when gets encounters the end of file of mark. Like scanf, fscanf also returns the numbers of items that are successfully read. When the end of the file is reached, it returns the value eof. 6. Write a program to sort the elements whose worst and average case is o(n log n)? Ans: The sorting technique which has worst and average case o(n log n) is merge sort. The merge sort is the sorting technique used to merge two sorted lists. If sorted lists are not given, first lists are to be sorted individually using any sorting techniques. Of all sorting techniques, quick sort is most efficient for sorting purpose. Program #include <stdio.h>

C.52 Solved Question Papers #include <conio.h> #define MAX_ARY 10 void merge_sort(int x[], int end, int start); int main(void) { int ary[MAX_ARY]; int j = 0; printf("\n\nEnter the elements to be sorted: \n"); for(j=0;j<MAX_ARY;j++) scanf("%d",&ary[j]); /* array before mergesort */ printf("Before :"); for(j = 0; j < MAX_ARY; j++) printf(" %d", ary[j]); printf("\n"); merge_sort(ary, 0, MAX_ARY - 1); /* array after mergesort */ printf("After Merge Sort :"); for(j = 0; j < MAX_ARY; j++) printf(" %d", ary[j]); printf("\n"); getch(); } /* Method to implement Merge Sort*/ void merge_sort(int x[], int end, int start) { int j = 0; const int size = start - end + 1; int mid = 0; int mrg1 = 0; int mrg2 = 0; int executing[MAX_ARY]; if(end == start) return; mid = (end + start) / 2;

Solved Question Papers merge_sort(x, end, mid); merge_sort(x, mid + 1, start); for(j = 0; j < size; j++) executing[j] = x[end + j]; mrg1 = 0; mrg2 = mid - end + 1; for(j = 0; j < size; j++) { if(mrg2 <= start - end) if(mrg1 <= mid - end) if(executing[mrg1] > executing[mrg2]) x[j + end] = executing[mrg2++]; else x[j + end] = executing[mrg1++]; else x[j + end] = executing[mrg2++]; else x[j + end] = executing[mrg1++]; } }

If the given two lists are not sorted lists, sort the lists using quick sort. Program #include<stdio.h> main() { int x[10],i,n; clrscr(); printf("enter no of elements:"); scanf("%d",&n); printf("enter %d elements:",n); for(i=1;i<=n;i++) scanf("%d",&x[i]); quicksort(x,1,n); printf("sorted elements are:"); for(i=1;i<=n;i++) printf("%3d",x[i]); getch(); } quicksort(int x[10],int first,int last)

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C.54 Solved Question Papers { int pivot,i,j,t; if(first<last) { pivot=first; i=first; j=last; while(i<j) { while(x[i]<=x[pivot] && i<last) i++; while(x[j]>x[pivot]) j--; if(i<j) { t=x[i]; x[i]=x[j]; x[j]=t; } } t=x[pivot]; x[pivot]=x[j]; x[j]=t; quicksort(x,first,j-1); quicksort(x,j+1,last); } } Merge Sort Process

A = {56,78}; B = {45,67,89} two sorted lists. C = {45,56,67,78,89} A B C

56, 78 45, 67, 45 56

A B C A B C

56, 78 45, 67, 89 45 56 56 78 45 67 89 45 56 67

89

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A B C

56 45 45

78 67 56

89 67

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78

C = {45,56,67,78,89} is the final sorted list using merge sort. 7. Give an algorithm/C program to reverse a singly linked circular list in place. Ans: Circular linked list: The small change to the structure of a linear list such that the link field in the last node contains a pointer back to the first node rather than a NULL. Such a list is called a circular linked list. 10

17

18

5

Here is the routine which reverses circular list. typedef struct node Node; void reverse(Node** headRef) { Node* result = NULL; Node* current = *headRef; Node* next; while (current != NULL) { next = current->next; // tricky: note the next node current->next = result; // move the node onto the result result = current; current = next; if (current == *headRef) { //met the beginning node... break; } } (*headRef)->next = result; *headRef = result; }

C.56 Solved Question Papers Program #include<conio.h> #include<stdio.h> struct node { int data; struct node *next; }; struct node *root; void addnode() { int item; struct node *newnode,*p; printf("\n Enter the item"); scanf("%d", &item); newnode=(struct node*) malloc(sizeof(struct node)); newnode->data=item; newnode->next=NULL; if(root==NULL) { root=newnode; return; } ____ _________ ________ p=root; while(p->next!=NULL) p=p->next; p->next=newnode; } void display() { struct node*p=root; while(p!=NULL) { printf("\n %d ",p->data); p=p->next; } } void reverse() { struct node *p,*oldnode=NULL,*newnode; p=root; while(p!=NULL)

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{ newnode=p; p=p->next; if(oldnode==NULL) { oldnode=newnode; oldnode->next=NULL; } else { newnode->next=oldnode; oldnode=newnode; } } root=oldnode; } void main() { int i; clrscr(); for(i=1;i<=10;i++) { addnode(); } printf("\nbefore reverse"); display(); printf("\n After reverse"); reverse(); display(); return 0; }

8. Write an algorithm to perform deletion operation in a binary tree search? Ans: There are four possible cases that we need to consider (a) No node in the tree contains the specified data (b) The node containing the data has no children (c) The node containing data has exactly one child (d) The node containing data has two children Case a: We merely need to print the message that data item is not present in the tree. Case b: Since the node to be deleted has no children, the memory occupied by this should be freed and either the left link or right link of parent of this node should be set to NULL. Which of these to set to NULLL, depends upon whether the node being deleted is a left child or a right child of its parent.

C.58 Solved Question Papers Case c: Since the node to be deleted has one child, the solution is again rather simple. We have to adjust the pointer of the parent of the node to be deleted, such that after deletion it points to child of node being deleted. 20 23

17 20

6

29

9

25

18

24

10

5

23

17

25

18

6

After deletion

29

24

8

5

10 9 Before deletion

Case d: Since the node to be deleted has two children, the solution is more complex. The whole logic of deleting a node with two children is to locate the in-order successor, copy its data and reduce the problem to a simple deletion of a node with one or zero child. 20 23

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6 5

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Algorithm to perform deletion operation in a binary search tree. ALGORITHM: Step 1:

Start

Step 2:

Define a structure btree

Step 3:

Type define struct btree as node

Step 4:

While(tree), begin

Step 5:

Print MENU

Step 6:

Write your choice

Solved Question Papers

Step 7:

If choice=1

Step 8:

Enter your no of nodes

Step 9:

Read nodes n

Step 10: for i=1 to n in steps of 1 do Step 11: Print enter item Step 12: Read item Step 13: Root =call create (root, item).end for Step 14: if choice=2 Step 15: Read element to be deleted Step 16: Call delete(root, item) end for Step 17: If choice=3 Step 18: Call preorder(root) Step 19: Call postorder(root) Step 20: Call inorder(root) Step 21: Break, end of switch Step 22: Stop For insert function Step 1:

Start

Step 2:

If t= null

Step 3:

Allocate memory to temp

Step 4:

Temp->data =item

Step 5:

Temp-> lc=null

Step 6:

Temp->rc=null

Step 7:

return t to main and end

Step 8:

If item< (l->data)

Step 9:

T->lc=call insert(e->lc, t)

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C.60 Solved Question Papers Step 10: T->rc=call insert(e->lc,t) Step 11: Return t Step 12: Stop For DELETION function Step 1:

Start

Step 2:

x=d

Step 3:

while x!=null

Step 4:

If x->data =t

Strep5:

Break

Step 6:

Parent =x

Step 7:

if t<x->data

Step 8:

t=tÆlc

Step 9:

t=lÆrc

Step 10: If xÆlc!=null &&xÆrc!=null Step 11: parent =x Step 12: If parent==null Step 13: parentÆlc==null Step 14: parentÆrc==null Step 15: If p->lc=x->rc Step 16: If p->rc=x->rc Step 17: While insert->lc=null Step 18: Insert=insert->la Step 19: x->data=insert->data Step 20: x=insert Step 21: Return d Step 22: Stop

Solved Question Papers

Processing to perform deletion operation in a binary search tree. Binary tree before deletion 7 8 9 10 11 12 13 14 15 Delete element 10 Binary tree after deletion 7 8 9 11 12 13 14 15

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