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

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1 INTERNAL ASSESSMENT TEST-3 Date : 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 :11.30 am to 1.00 Ms.Swati/Ms.Bhuvaneswari pm Note: Answer FIVE full questions, selecting any ONE full question from each part. PART 1 1 a What is structure? Explain the syntax of structure declaration with example. Structure is a collection of elements of different data type. 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; ; This declaration above creates the derived data type struct person. b What is file? Explain how the file open and file close function handled in C. 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. 4 4

2 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 Closing a File The file should be closed after reading/writing of a file. fclose( ) function can be used to close a file. The syntax is shown below: int fclose(file *fp); The fclose( ) function returns zero on success or returns EOF(special character) if there is an error 2 Explain how to pass structure to function by value and by address. passing structure to function in C by value: In this program, the whole structure is passed to another function by value. It means the whole structure is passed to another function with all members and their values. So, this structure can be accessed from called function. This concept is very useful while writing very big programs in C. 8 #include <stdio.h> #include <string.h> struct student int id; char name[20]; float percentage; ; void func(struct student record);

3 int main() struct student record; record.id=1; strcpy(record.name, "Raju"); record.percentage = 86.5; func(record); return 0; void func(struct student record) printf(" Id is: %d \n", record.id); printf(" Name is: %s \n", record.name); printf(" Percentage is: %f \n", record.percentage); Passing structure to function in C by address: In this program, the whole structure is passed to another function by address. It means only the address of the structure is passed to another function. The whole structure is not passed to another function with all members and their values. So, this structure can be accessed from called function by its address. #include <stdio.h> #include <string.h> struct student

4 int id; char name[20]; float percentage; ; void func(struct student *record); int main() struct student record; record.id=1; strcpy(record.name, "Raju"); record.percentage = 86.5; func(&record); return 0; void func(struct student *record) printf(" Id is: %d \n", record->id); printf(" Name is: %s \n", record->name); printf(" Percentage is: %f \n", record->percentage); PART 2 3 Write a C program to maintain a record of N student detail using an array of structures with four fields (USN, Name, Marks, and Grade).Each field is of appropriate data type. Print the marks of the student, given student name as input. 8

5 #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)

6 Found = 1; printf("\nmarks obtained by %s is %d\n", s[i].name, s[i].marks); exit(0); if(found == 0) printf("\nno student by name %s found\n", StudName); 4 a Write a C program to add two complex numbers by passing structure to a function. 8 #include <stdio.h> struct complex float real; float imag; ; struct complex add(struct complex n1,struct complex n2); int main() 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);

7 getch(); return 0; 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); PART 3 5 Given two university information files studentname.txt and usn.txt that containsstudents Name and USN respectively. Write a C program to create a new file called output.txt and copy the content of files studentname.txt and usn.txt into output file. Display the contents of output file output.txt on tothe screen. 8 #include<stdio.h> #include<stdlib.h> main() FILE *fp1,*fp2,*fp3; char usn[10],name[20]; fp1=fopen("studentname.txt","r"); if(fp1==null) printf("\n Error opening studentname.txt\n"); exit(0); fp2=fopen("usn.txt","r"); if(fp2==null) printf("\n Error opening usn.txt\n"); exit(0);

8 fp3=fopen("output.txt","w"); if(fp2==null) printf("\n Error opening output.txt\n"); exit(0); while(!feof(fp1) &&!feof(fp2) ) fscanf(fp1,"%s",name); fscanf(fp2,"%s",usn); fprintf(fp3,"%s \t %s \n",name,usn); fclose(fp1); fclose(fp2); fclose(fp3); fp3=fopen("output.txt","r"); printf("\nname \t USN \n\n"); while(!feof(fp3) ) fscanf(fp3,"%s",name); fscanf(fp3,"%s",usn); printf("%s \t %s \n",name,usn); fclose(fp3); 6 a What is a pointer? Explain how the pointer variable declared and initialized. A pointer is a variable which holds address of another variable or a memory-location. For ex: c=300; pc=&c; Here pc is a pointer; it can hold the address of variable c & is called reference operator DECLARATION OF POINTER VARIABLE Dereference operator(*) are used for defining pointer-variable. The syntax is shown below: data_type *ptr_var_name; For ex: 4

9 int *a; // a as pointer variable of type int float *c; // c as pointer variable of type float Steps to access data through pointers: 1) Declare a data-variable ex: int c; 2) Declare a pointer-variable ex: int *pc; 3) Initialize a pointer-variable ex: pc=&c; 4) Access data using pointer-variable ex: printf("%d",*pc); Code int* pc; creates a pointer pc and code int c; Code c=22; makes the value of c equal to 22, Code pc=&c; makes pointer, point to address of c. b Explain storage classes in C. There are following storage classes which can be used in a C Program auto register static extern Auto int Count; //count is a variable that belongs to auto storage class; auto is the default storage class for all local variables. 4 variables. Register register int a; register is used to define local variables that should be stored in a register instead of RAM. This means that the variable cant have the unary '&' operator applied to it (as it does not have a memory Extern extern is used to give a reference of a global variable that is visible to ALL the program files. int count=5; main()

10 write_extern( ); File 1: main.c void write_extern(void); extern int count; void write_extern(void) printf("count is %d\n", count); File 2: write.c Static static is the default storage class for global variables. static variables can be 'seen' within all functions in this source file. At link time, the static variables defin not be seen by the object modules that are brought in. Static can also be defined within a function If this is done the variable is initalised at run time but is not reinitalized when the function is called. This inside a function static variable retains its value during vairous calls. PART 4 7 a What is dynamic memory allocation? Explain malloc and calloc dynamic allocation functions in C and also explain the difference between malloc and calloc. C Dynamic Memory Allocation: malloc(), calloc(), free() & realloc() 4 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.

11 calloc() malloc() calloc() initializes the allocated memory with 0 value. malloc() initializes the allocated memory with garba values. Number of arguments is 2 Number of argument is 1 Syntax : (cast_type *)calloc(blocks, size_of_block); Syntax : (cast_type *)malloc(size_in_bytes); malloc() The name malloc stands for "memory allocation". This function is used to allocate the requirement memory-space during executiontime. The syntax is shown below: data_t ype *p; p=(dat a_type *)mall oc(siz e); here p is pointer variable data_type can be int, float or char size is number of bytes to be allocated If memory is successfully allocated, then address of the first byte of allocated space is returned. If memory allocation fails, then NULL is returned. For ex: ptr=(int*)malloc(100*sizeof(int)); The above statement will allocate 200 bytes assuming sizeof(int)=2 bytes. calloc() The name calloc stands for "contiguous allocation".

12 b This function is used to allocate the required memory-size during execution-time and at the same time, automatically initialize memory with 0's. The syntax is shown below: data_ty pe *p; p=(data _type*) calloc( n,size); If memory is successfully allocated, then address of the first byte of allocated space is returned. If memory allocation fails, then NULL is returned. The allocated memory is initialized automatically to 0's. For ex: ptr=(int*)calloc(25,sizeof(int)); The above statement allocates contiguous space in memory for an array of 25 elements each of size of int, i.e., 2 bytes. Write a program to find the largest of two numbers using call by pointer method. #include<stdio.h> Int * largest(int * m,int *n) If(*m>*n) Return (m); Else Return n; Void main() Int x,y; Int *p; Printf( enter two numbers ); Scanf( %d%d,&x,&y); P=largest(&x,&y); Printf( largest of two number is %d,*p); 4 8 Designs develop and execute a program in C to simulate the working of queue of integers using an array. Provide the following operations 1.Insert 2.Delete3.Display. 8

13 #include <stdio.h> #define MAX 50 int queue_array[max], rear = - 1, front = - 1; insert() int add_item; if (rear == MAX - 1) printf("queue Overflow "); else if (front == - 1) //If queue is initially empty front = 0; printf("insert the element in queue : "); scanf("%d", &add_item); rear=rear+1; queue_array[rear]=add_item; delete() if (front == - 1 front > rear) printf("queue Underflow \n"); return ; else printf("element deleted from queue is : %d\n", queue_array[front]); front = front + 1; display() int i; if (front == - 1)

14 printf("queue is empty \n"); else printf("queue is : \n"); for (i = front; i <= rear; i++) printf("%d ", queue_array[i]); printf("\n"); main() int choice; while (1) printf("1.insert element to queue \n"); printf("2.delete element from queue \n"); printf("3.display all elements of queue \n"); printf("4.quit \n"); printf("enter your choice : "); scanf("%d", &choice); switch (choice) case 1: insert(); break; case 2: delete(); break; case 3: display(); break; case 4: exit(1); default: printf("wrong choice \n"); //End of switch //End of while //End of main() PART 5

15 9 a What are primitive and non-primitive data types? PRIMITIVE AND NON-PRIMITIVE DATA TYPES Data type specifies the type of data stored in a variable. The data type can be classified into two types: 1) Primitive data type and 2)Non-Primitive data type Primitive Data Type The primitive data types are the basic data types that are available in most of the programming languages. The primitive data types are used to represent single values. Integer: This is used to represent a number without decimal point. Eg: 12, 90 Float: This is used to represent a number with decimal point. Eg: 45.1, 67.3 Character: This is used to represent single character Eg: C, a String: This is used to represent group of characters. Eg: "M.S.P.V.L Polytechnic College" Boolean: This is used represent logical values either true or false. Non Primitive Data Type The data types that are derived from primary data types are known as non-primitive data types. These datatypes are used to store group of values. The non-primitive data types are Arrays Structure Stacks Linked list Queue Binary tree 4 b What is a stack? Explain with its applications. STACKS A stack is a special type of data structure where elements are inserted from one end and elements are deleted from the same end. Using this approach, the Last element Inserted is the First element to be deleted Out, and hence, stack is also called LIFO data structure. The various operations performed on stack: Insert: An element is inserted from top end. Insertion operation is called push operation. Delete: An element is deleted from top end. Deletion operation is called pop operation. Overflow: Check whether the stack is full or not. Underflow: Check whether the stack is empty or not. 4

16 This can be pictorially represented as shown above: APPLICATIONS OF STACK 1) Conversion of expressions: The compiler converts the infix expressions into postfix expressions using stack. 2) Evaluation of expression: An arithmetic expression represented in the form of either postfix or prefix can be easily evaluated using stack. 3) Recursion: A function which calls itself is called recursive function. 4) Other applications: To find whether the string is a palindrome, to check whether a given expression is valid or not. 1 0 Write a C program to find the sum, mean and variance of all the elements in an array using pointers. #include<stdio.h> #include<math.h> 8 float findsum(float [], int); float findmean(float, int); float findstddev(float [],int,float); main() float a[20],mean,sum, stddev; int n,i; float *p; p=&a; printf("enter the No of elements \n"); scanf("%d",&n); printf("enter the elements\n"); for(i=0;i<n;i++) scanf("%f",p);

17 p++; sum=findsum(a,n); mean=findmean(sum,n); stddev=findstddev(a,n,mean); printf("\nsum: %f",sum); printf("\nmean: %f",mean); printf("\n Standard Deviation: %f",stddev); float findsum(float a[],int n) int *p; p=a; float sum=0; int i; for(i=0;i<n;i++) sum=sum + *p; p++; return sum; float findmean(float sum,int n) return sum/n;

18 float findstddev(float a[],int n,float mean) int i,*p; p=&a[0]; float stddev=0,variance,sumd=0; for(i=0; i<n;i++) sumd=sumd+pow((*p - mean),2); p++; variance=sumd/n; stddev= sqrt(variance); return stddev;

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