Bangalore South Campus

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1 USN: 1 P E PESIT Bangalore South Campus Hosur road, 1km before ElectronicCity, Bengaluru -100 Department of Basic Science and Humanities INTERNAL ASSESSMENT TEST 3 Date: 22/11/2017 Time:11:30am pm Marks: 40 Subject & Code: Programming in C and Data Structures- 17PCD13 Sem I: A, B, C, D, E Name of faculty: Dr. J Surya Prasad/ Mr. Naushad / Ms. Vandana/ Ms. Monika. Q 1 a) What is a string? Explain strcpy(),strcat(), strlen(),strcmp() with examples Q1 b) Write a program to read a string and findthe length of the stringusing user de function(without using strlen() function) efined

$h> intmain() int n,i,mid,low,high,item,a[10]; printf("enter the value of n\n"); scanf("%d",&n); printf("enter all the values"); for(i=0;i<n;i++) scanf("%d",&a[i]);$ $printf("enter the number "); scanf("%d",&item); low=0; high=n-1; while(low<=high) mid=(low+high)/2; if(a[mid]==item) printf("found\n"); exit(0); if(item<a[mid]) high=mid-1;$ Structure is a collection of elements of different data type.

Structure is a collection of elements of different data type.

2 Q 2 Write a program to search a name in a list of names using binary search technique. Binary search for Numbers #include <stdio.h> #include <stdlib.h> intmain() int n,i,mid,low,high,item,a[10]; printf("enter the value of n\n"); scanf("%d",&n); printf("enter all the values"); for(i=0;i<n;i++) scanf("%d",&a[i]); printf("enter the number "); scanf("%d",&item); low=0; high=n-1; while(low<=high) mid=(low+high)/2; if(a[mid]==item) printf("found\n"); exit(0); if(item<a[mid]) high=mid-1; else low=mid+1; printf("not found"); Q 3 a) What is Structure? How structure is different from an array? Explain declaration of a structure with an example. Structure is a collection of elements of different data type. Array is collection of similar data elements The syntax is shown below: struct structure_name data_type member1; data_type member2; data_type member3; ; The variables that are used to store the data are called members of the structure. We can create the structure for a person as shown below: struct person char name[50]; int cit_no; float salary; ;

3 Q 3 b) Explain how the structure variable can be passed to a function. Write a program to add two complex numbers by passing structures to a function. #include <stdio.h> struct complex float real; float imag; ; struct complex add(struct complex n1,struct complex n2); struct complex n1,n2,n_sum; printf("for 1st complex number \n"); printf("enter real and imaginary respectively:\n"); scanf("%f%f",&n1.real,&n1.imag); printf("\nfor 2nd complex number \n"); printf("enter real and imaginary respectively:\n"); scanf("%f%f",&n2.real,&n2.imag); n_sum=add(n1,n2); printf("sum=%f+%fi",n_sum.real,n_sum.imag); getch(); struct complex add(struct complex n1,struct complex n2) struct complex temp; temp.real=n1.real+n2.real; temp.imag=n1.imag+n2.imag; return(temp);

4 Q 4 ) Write a C program to maintain a record of "n" student details using an array of structures with three fields (Name, marks, and Grade). Each field is of an appropriate data type. Implement linear search to search a student based on name #include <stdio.h> #include <stdlib.h> struct Student int Marks,RollNo; char Name[30],Grade; ; void main() struct Student s[20]; int i, Num, Found = 0; char StudName[30]; printf("\nenter the number of students\n"); scanf("%d", &Num); printf("\nenter Student Details\n"); for(i=0;i<num;i++) printf("\nstudent %d\n\nrollno : ", i+1); scanf("%d", &s[i].rollno); printf("\nname : "); scanf("%s",&s[i].name); printf("\nmarks : "); scanf("%d",&s[i].marks); printf("\ngrade : "); scanf("%s",&s[i].grade); printf("\n\n\n"); printf("\nenter the name to display marks\n"); scanf("%s",&studname); for(i=0;i<num;i++) if(strcmp(studname,s[i].name)==0) Found = 1; printf("\nmarks obtained by %s is %d\n", s[i].name, s[i].marks); exit(0); if(found == 0)

5 printf("\nno student by name %s found\n", StudName); Q 5 a ) What is a file? Explain the various modes in which a file can be opened successfully DEFINING, OPENING AND CLOSING OF FILES A file represents a sequence of bytes, regardless of it being a text file or a binary file. Defining a File While working with file, you need to declare a pointer of type FILE?. This declaration is needed for communication between file and program. FILE *ptr; Opening a File fopen( ) function can be used to create a new file or to open an existing file This function will initialize an object of the type FILE, which contains all the information necessary to control the stream. The syntax is shown below: FILE *fopen( const char *filename, const char *access_mode ); where filename is string literal, which you will use to name your file. access_mode can have one of the following values: Mode Description r Opens an existing text file for reading purpose w Opens a text file for writing, if it does not exist then a new file is created a Opens a text file for writing in appending mode r+ Opens a text file for reading and writing both Q 5 b ) write a program to copy the contents form one file to another. int ch; FILE *f1 = fopen("stud.txt", "r"); FILE *f2 = fopen("out.txt", "w"); do ch = getc(f1); putc(f2,ch); while (ch!= EOF); fclose(f1); fclose(f2);

6 Q 6 ) Given a text file called student.txt thatcontains student details(name and marks) of one subject. Write a program to generate a report of students having marks < 12. #include <stdio.h> FILE *fp = fopen("stud.txt", "r"); char usn[30]; char name[15]; int marks; do fscanf(fp,"%s %s %d",usn,name,&marks); if(marks<12) printf("%s %s %d\n",usn,name,marks); while(!feof(fp)); fclose(fp); Q 7 a) What are wild and dangling pointers? Explain with examples. A pointer which has not been initialized to anything (not even NULL) is known as wild pointer. The pointer may be initialized to a non-null garbage value that may not be a valid address. int *p; /* wild pointer */ int x = 10; // p is not a wild pointer now p = &x; Dangling pointers arise when an object is deleted or de-allocated, without modifying the value of the pointer, so that the pointer still points to the memory location of the de-allocated memory. In short pointer pointing to non-existing memory location is called dangling pointer. Dangling pointer // Deallocating a memory pointed by ptr causes dangling pointer #include <stdlib.h> #include <stdio.h> int *ptr = (int *)malloc(sizeof(int));

7 // After below free call, ptr becomes a // dangling pointer free(ptr); // No more a dangling pointer ptr = NULL; Q 7 b) What is pointer to a structure? And also, explain with program passing structures to functions by reference. struct student int id; char name[20]; int percentage; ; struct student s=1,"ram",90; display(&s); void display(struct student *p) printf(" Id is: %d \n", p->id); printf(" Name is: %s \n", p->name); printf(" Percentage is: %d \n", p->percentage); P is a pointer to structure called student. Q 8 ) What is Dynamic memory allocation? Explainmalloc(),calloc(),realloc() and free()? The exact size of array is unknown untill the compile time,i.e., time when a compier compiles code written in a programming language into a executable form. The size of array you have declared initially can be sometimes insufficient and sometimes more than required. Dynamic memory allocation allows a program to obtain more memory space, while running or to release space when no space is required. Although, C language inherently does not has any technique to allocated memory dynamically, there are 4 library functions under "stdlib.h" for dynamic memory allocation. Dynamic memory allocation Using malloc() function ptr=(cast-type*)malloc(byte-size) Ex Int *ptr=malloc(100*sizeof(int)); //dynamic Int *ptr=malloc(n*sizeof(int)); //dynamic

8 Memory Allocation Functions malloc Allocates requested number of bytes and returns a pointer to the first byte of the allocated space. calloc Allocates space for an array of elements, initializes them to zero and then returns a pointer to the memory. free Frees previously allocated space. realloc Modifies the size of previously allocated space. int n; char *name; printf("enter the length of the name: "); scanf("%d",&n); name=(char*)malloc(n*sizeof(char)); printf("enter the name: "); scanf(" "); /*clear input buffer*/ gets(name); printf("your name is %s\n",name); free(name); /*Free Memory*/ Q 9 a ) What is data structure?explain primitive and non-primitive data types. Organizing and storing data Anything that can store data can be called as a data structure.

9 Q 9 b) Define Stack and Linked List with example and mention the applications Stacks It is a linear data structure(with fixed capacity) It is considered as sequence of items. It is a LIFO structure(last In First Out). It has two components: A Container of items that contains elements of queue. A pointer top that points the recently added item. Different Operations on stack push() function is used to insert new elements into the Stack pop() is used to delete an element from the stack Display(); to display the contents of stack Conditions in stack implementation are Stack full Stack empty Applications. Expression Conversion (Infix to Postfix, Postfix to Prefix etc) To reverse a string and to find palindromes: Push a given word to stack - letter by letter - and then pop letters from the stack and SMS inbox. Parsing. Backtracking in web pages. Functions (address of the next instruction to be executed is pushed onto the stack)

10 Operations on linked lists. Insert a new item At the head of the list, or At the tail of the list, or Inside the list, in some designated position Search for an item in the list The item can be specified by position, or by some value Delete an item from the list Search for and locate the item, then remove the item, and finally adjust the surrounding pointers size( ); isempty( ) Applications : Linked lists are useful for dynamic memory allocation. Linked Lists can be used to implement Stacks, Queues. Linked Lists can also be used to implement Graphs Q 10 ) Define Queue. Explain its operation with example. What are its applications? It is a linear data structure. It is considered as sequence of items. It supports FIFO (First In First Out) property. It has three components: A Container of items that contains elements of queue. A pointer front that points the first item of the queue. A pointer rear that points the last item of the queue. Insertion is performed from REAR end. Deletion is performed from FRONT end. Queue can be implementing by two ways: 1) Array or contiguous implementation. 2) Linked List implementation. There are five operations possible on a queue: Initialize operation (rear=front=-1) Addition or insertion operation. Deletion operation. Display Q contents Is_full check(rear=max-1) Is_empty check(front=-1 or front >rear) Applications Serving requests on a single shared resource, like a printer, CPU task scheduling etc. (FCFS) In real life, Call Centre phone systems will use Queues, to hold people calling them in an order, until a service representative is free. Handling of interrupts in real-time systems.

PESIT Bangalore South Campus Hosur road, 1km before ElectronicCity, Bengaluru -100 Department of Basic Science and Humanities

PESIT Bangalore South Campus Hosur road, 1km before ElectronicCity, Bengaluru -100 Department of Basic Science and Humanities INTERNAL ASSESSMENT TEST-3 Date : 12-05-2016 Marks: 40 Subject & Code : Programming in C and data structures (15PCD23) Sec : F,G,H,I,J,K Name of faculty :Dr J Surya Prasad/Mr.Sreenath M V/Ms.Monika/ Time