assignment 4

 

1. Define a structure in C. Write the syntax for structure declaration with an example.

In C, a structure is a user-defined data type that can hold different types of data. A structure is defined using the struct keyword.

Syntax for structure declaration:

struct structure_name {
    data_type member1;
    data_type member2;
    // More members
};

Example:

#include <stdio.h>

// Defining a structure to store student details
struct Student {
    int roll_no;
    char name[50];
    float marks;
};

int main() {
    // Declaring and initializing a structure variable
    struct Student student1 = {101, "John Doe", 85.5};
    
    // Displaying the student's details
    printf("Roll Number: %d\n", student1.roll_no);
    printf("Name: %s\n", student1.name);
    printf("Marks: %.2f\n", student1.marks);
    
    return 0;
}

2. Declare the C structures for the following scenario:

(i) College contains the following fields: College code (2 characters), College Name, year of establishment, number of courses. (ii) Each course is associated with course name (String), duration, number of students.

C Structure Declaration:

#include <stdio.h>

struct Course {
    char course_name[50];
    int duration;  // Duration in months
    int num_students;
};

struct College {
    char college_code[3]; // 2 characters + null terminator
    char college_name[100];
    int year_of_establishment;
    int num_courses;
    struct Course courses[50];  // A college can offer up to 50 courses
};

3. Define a structure type personal, that would contain person name, date of joining, and salary. Write a program to initialize one person's data and display the same.

#include <stdio.h>

struct personal {
    char name[50];
    char date_of_joining[20];
    float salary;
};

int main() {
    struct personal p1 = {"John Doe", "01-01-2020", 75000.50};
    
    // Displaying the person's details
    printf("Name: %s\n", p1.name);
    printf("Date of Joining: %s\n", p1.date_of_joining);
    printf("Salary: %.2f\n", p1.salary);
    
    return 0;
}

4. Differentiate between structure and union in C with examples. Write a program in C to maintain a record of N employee detail using an array of structures with three fields (id, name, salary) and print the details of employees whose salary is above 60000.

Structure vs Union in C:

• Structure: In a structure, each member has its own memory location. The size of the structure is the sum of the sizes of its members.
• Union: In a union, all members share the same memory location, and only one member can hold a value at any given time. The size of the union is the size of the largest member.

Example of structure:

struct Employee {
    int id;
    char name[50];
    float salary;
};

Example of union:

union Data {
    int i;
    float f;
    char str[20];
};

Program to maintain a record of N employee detail:

#include <stdio.h>

struct Employee {
    int id;
    char name[50];
    float salary;
};

int main() {
    int n;
    printf("Enter number of employees: ");
    scanf("%d", &n);
    
    struct Employee employees[n];
    
    // Input employee details
    for (int i = 0; i < n; i++) {
        printf("Enter details for employee %d\n", i + 1);
        printf("ID: ");
        scanf("%d", &employees[i].id);
        printf("Name: ");
        scanf("%s", employees[i].name);
        printf("Salary: ");
        scanf("%f", &employees[i].salary);
    }
    
    // Print employees with salary > 60000
    printf("\nEmployees with salary above 60000:\n");
    for (int i = 0; i < n; i++) {
        if (employees[i].salary > 60000) {
            printf("ID: %d, Name: %s, Salary: %.2f\n", employees[i].id, employees[i].name, employees[i].salary);
        }
    }
    
    return 0;
}

5. Define a structure type book, that would contain book name, author, pages, and price. Write a program to read this data using member operator (‘.’) and display the same.

#include <stdio.h>

struct Book {
    char name[50];
    char author[50];
    int pages;
    float price;
};

int main() {
    struct Book book1;
    
    // Input book details
    printf("Enter book name: ");
    scanf("%s", book1.name);
    printf("Enter author name: ");
    scanf("%s", book1.author);
    printf("Enter number of pages: ");
    scanf("%d", &book1.pages);
    printf("Enter price: ");
    scanf("%f", &book1.price);
    
    // Displaying book details
    printf("\nBook Details:\n");
    printf("Name: %s\n", book1.name);
    printf("Author: %s\n", book1.author);
    printf("Pages: %d\n", book1.pages);
    printf("Price: %.2f\n", book1.price);
    
    return 0;
}

6. How to pass a structure member as an argument of a function? Write a program to explain it.

Passing a structure member to a function:

#include <stdio.h>

struct Student {
    int roll_no;
    char name[50];
    float marks;
};

// Function to display student marks
void displayMarks(float marks) {
    printf("Marks: %.2f\n", marks);
}

int main() {
    struct Student student1 = {101, "John Doe", 85.5};
    
    // Passing the structure member to the function
    displayMarks(student1.marks);
    
    return 0;
}

7. What is an array of structure? Declare a variable as an array of structure and initialize it.

An array of structures is an array where each element is a structure variable.

Syntax:

struct structure_name array_name[size];

Example:

#include <stdio.h>

struct Student {
    int roll_no;
    char name[50];
};

int main() {
    struct Student students[2] = {
        {101, "John Doe"},
        {102, "Jane Smith"}
    };
    
    for (int i = 0; i < 2; i++) {
        printf("Roll Number: %d, Name: %s\n", students[i].roll_no, students[i].name);
    }
    
    return 0;
}

8. Write a C program to calculate student-wise total marks for three students using an array of structure.

#include <stdio.h>

struct Student {
    int roll_no;
    char name[50];
    float marks[3]; // Array of marks for 3 subjects
    float total;
};

int main() {
    struct Student students[3];
    
    // Input details for 3 students
    for (int i = 0; i < 3; i++) {
        printf("Enter details for student %d\n", i + 1);
        printf("Roll Number: ");
        scanf("%d", &students[i].roll_no);
        printf("Name: ");
        scanf("%s", students[i].name);
        
        students[i].total = 0; // Initialize total to 0
        for (int j = 0; j < 3; j++) {
            printf("Enter marks for subject %d: ", j + 1);
            scanf("%f", &students[i].marks[j]);
            students[i].total += students[i].marks[j];
        }
    }
    
    // Displaying total marks for each student
    for (int i = 0; i < 3; i++) {
        printf("Total marks for %s (Roll No: %d) = %.2f\n", students[i].name, students[i].roll_no, students[i].total);
    }
    
    return 0;
}

9. Write a C program using an array of structure to create employee records with the following fields: emp-id, name, designation, address, salary and display it.

#include <stdio.h>

struct Employee {
    int emp_id;
    char name[50];
    char designation[50];
    char address[100];
    float salary;
};

int main() {
    struct Employee employees[3];
    
    // Input employee details
    for (int i = 0; i < 3; i++) {
        printf("Enter details for employee %d\n", i + 1);
        printf("Employee ID: ");
        scanf("%d", &employees[i].emp_id);
        printf("Name: ");
        scanf("%s", employees[i].name);
        printf("Designation: ");
        scanf("%s", employees[i].designation);
        printf("Address: ");
        scanf(" %[^\n]%*c", employees[i].address); // To read multi-word address
        printf("Salary: ");
        scanf("%f", &employees[i].salary);
    }
    
    // Display employee details
    printf("\nEmployee Records:\n");
    for (int i = 0; i < 3; i++) {
        printf("Employee ID: %d, Name: %s, Designation: %s, Address: %s, Salary: %.2f\n",
            employees[i].emp_id, employees[i].name, employees[i].designation,
            employees[i].address, employees[i].salary);
    }
    
    return 0;
}

10. What is structure within structure? Give an example for it.

Structure within structure (or nested structure) is when a structure contains another structure as a member.

Example:

#include <stdio.h>

struct Address {
    char city[50];
    char state[50];
};

struct Employee {
    int emp_id;
    char name[50];
    struct Address addr;  // Structure within structure
};

int main() {
    struct Employee emp = {1, "John Doe", {"New York", "NY"}};
    
    printf("Employee ID: %d\n", emp.emp_id);
    printf("Name: %s\n", emp.name);
    printf("City: %s\n", emp.addr.city);
    printf("State: %s\n", emp.addr.state);
    
    return 0;
}

11. Write a C program using nested structures to read 3 employee details with the following fields: emp-id, name, designation, address, da, hra, and calculate gross salary of each employee.

#include <stdio.h>

struct Address {
    char city[50];
    char state[50];
};

struct Employee {
    int emp_id;
    char name[50];
    char designation[50];
    struct Address addr;  // Nested structure
    float da;  // Dearness Allowance
    float hra; // House Rent Allowance
    float gross_salary;  // Gross salary
};

int main() {
    struct Employee employees[3];
    
    // Input employee details and calculate gross salary
    for (int i = 0; i < 3; i++) {
        printf("Enter details for employee %d\n", i + 1);
        printf("Employee ID: ");
        scanf("%d", &employees[i].emp_id);
        printf("Name: ");
        scanf("%s", employees[i].name);
        printf("Designation: ");
        scanf("%s", employees[i].designation);
        printf("City: ");
        scanf("%s", employees[i].addr.city);
        printf("State: ");
        scanf("%s", employees[i].addr.state);
        printf("Dearness Allowance: ");
        scanf("%f", &employees[i].da);
        printf("House Rent Allowance: ");
        scanf("%f", &employees[i].hra);
        
        // Calculating Gross Salary
        employees[i].gross_salary = employees[i].da + employees[i].hra;
    }
    
    // Display employee details with gross salary
    for (int i = 0; i < 3; i++) {
        printf("\nEmployee ID: %d\n", employees[i].emp_id);
        printf("Name: %s\n", employees[i].name);
        printf("Designation: %s\n", employees[i].designation);
        printf("Address: %s, %s\n", employees[i].addr.city, employees[i].addr.state);
        printf("Gross Salary: %.2f\n", employees[i].gross_salary);
    }
    
    return 0;
}

12. Distinguish between Arrays within Structures and Array of Structure with examples.
Arrays within Structures and Array of Structures are two concepts in C where arrays and structures are used together. Let's distinguish between them:
Arrays within Structures:
An array is a member of a structure. This means that the structure contains an array as one of its members.
Example:
#include <stdio.h>

struct Student {
    int roll_no;
    char name[50];
    float marks[5];  // Array of 5 marks
};

int main() {
    struct Student student1 = {101, "John Doe", {85.5, 90.0, 88.0, 92.5, 79.0}};
    
    printf("Student Roll No: %d\n", student1.roll_no);
    printf("Student Name: %s\n", student1.name);
    printf("Marks in Subject 1: %.2f\n", student1.marks[0]);
    
    return 0;
}

Here, marks is an array within the structure Student. The structure holds an array of marks as one of its members.
Array of Structures:
An array of structures is an array where each element is a structure variable. Each structure in the array can have different values for its members.
Example:
#include <stdio.h>

struct Student {
    int roll_no;
    char name[50];
    float marks;
};

int main() {
    struct Student students[3] = {
        {101, "John", 85.5},
        {102, "Jane", 90.0},
        {103, "Alice", 88.5}
    };
    
    for (int i = 0; i < 3; i++) {
        printf("Roll No: %d, Name: %s, Marks: %.2f\n", students[i].roll_no, students[i].name, students[i].marks);
    }
    
    return 0;
}

Here, students is an array of structures. Each element of the array holds a structure representing a student's details.
13. Write a C program using structure to create a library catalog with the following fields: Access number, author’s name, Title of the book, year of publication, publisher’s name, and price.
#include <stdio.h>

struct LibraryCatalog {
    int access_number;
    char author_name[50];
    char title[100];
    int year_of_publication;
    char publisher_name[50];
    float price;
};

int main() {
    struct LibraryCatalog book1;
    
    // Input book details
    printf("Enter Access Number: ");
    scanf("%d", &book1.access_number);
    printf("Enter Author's Name: ");
    scanf(" %[^\n]s", book1.author_name);  // To allow spaces in the name
    printf("Enter Title of the Book: ");
    scanf(" %[^\n]s", book1.title);
    printf("Enter Year of Publication: ");
    scanf("%d", &book1.year_of_publication);
    printf("Enter Publisher's Name: ");
    scanf(" %[^\n]s", book1.publisher_name);
    printf("Enter Price: ");
    scanf("%f", &book1.price);
    
    // Display the book details
    printf("\nLibrary Catalog Information:\n");
    printf("Access Number: %d\n", book1.access_number);
    printf("Author: %s\n", book1.author_name);
    printf("Title: %s\n", book1.title);
    printf("Year of Publication: %d\n", book1.year_of_publication);
    printf("Publisher: %s\n", book1.publisher_name);
    printf("Price: %.2f\n", book1.price);
    
    return 0;
}

14. Explain in brief about pointers and structures. What is self-referential structure? Explain through an example.
Pointers and Structures:

Pointers store memory addresses of variables, including structures.
A pointer to a structure is used to access structure members via the pointer, using the -> operator.

Example of pointer to structure:
#include <stdio.h>

struct Student {
    int roll_no;
    char name[50];
};

int main() {
    struct Student student1 = {101, "John"};
    struct Student *ptr = &student1;
    
    // Accessing structure members using pointer
    printf("Roll No: %d, Name: %s\n", ptr->roll_no, ptr->name);
    
    return 0;
}

Self-Referential Structure:
A self-referential structure is a structure that contains a pointer to its own type.
Example of self-referential structure:
#include <stdio.h>

struct Node {
    int data;
    struct Node *next;  // Pointer to the same structure type
};

int main() {
    struct Node node1, node2;
    
    node1.data = 10;
    node1.next = &node2;  // Pointing to node2
    
    node2.data = 20;
    node2.next = NULL;
    
    // Print data from node1 and node2
    printf("Node1 Data: %d, Node2 Data: %d\n", node1.data, node2.data);
    
    return 0;
}

15. Discuss file handling in C in brief. Explain different modes of opening files with syntax and example.
File Handling in C:
File handling allows programs to read from and write to files. It uses the following functions:

fopen(): Opens a file.
fclose(): Closes a file.
fprintf(): Writes formatted data to a file.
fscanf(): Reads formatted data from a file.
fread() and fwrite(): Read and write binary data.

Modes of Opening Files:

r: Open a file for reading.
w: Open a file for writing (creates a new file or truncates an existing file).
a: Open a file for appending (adds to the end).
r+: Open a file for both reading and writing.
w+: Open a file for both reading and writing (creates a new file or truncates an existing file).
a+: Open a file for both reading and appending.

Example:
#include <stdio.h>

int main() {
    FILE *file;
    
    // Opening a file in write mode
    file = fopen("example.txt", "w");
    if (file == NULL) {
        printf("Error opening file.\n");
        return 1;
    }
    
    fprintf(file, "Hello, World!\n");
    
    fclose(file);  // Closing the file
    
    return 0;
}

16. What are the file I/O functions in C? Give a brief note about the task performed by each function.

fopen(): Opens a file.
fclose(): Closes a file.
fgetc(): Reads a character from a file.
fputc(): Writes a character to a file.
fgets(): Reads a string from a file.
fputs(): Writes a string to a file.
fprintf(): Writes formatted data to a file.
fscanf(): Reads formatted data from a file.
fread(): Reads binary data from a file.
fwrite(): Writes binary data to a file.
feof(): Checks if the end of the file has been reached.

17. Write a C program to copy the content of A.txt file into B.txt using file handling functions.
#include <stdio.h>

int main() {
    FILE *source, *destination;
    char ch;
    
    source = fopen("A.txt", "r");
    if (source == NULL) {
        printf("Error opening source file.\n");
        return 1;
    }
    
    destination = fopen("B.txt", "w");
    if (destination == NULL) {
        printf("Error opening destination file.\n");
        fclose(source);
        return 1;
    }
    
    // Copying content from A.txt to B.txt
    while ((ch = fgetc(source)) != EOF) {
        fputc(ch, destination);
    }
    
    printf("Content copied from A.txt to B.txt\n");
    
    fclose(source);
    fclose(destination);
    
    return 0;
}

18. What is a preprocessor directive? Explain #define and #include preprocessor directives. Explain any other five preprocessor directives in C.
Preprocessor Directives:
Preprocessor directives are instructions given to the preprocessor before the program is compiled. They are not executable but are processed by the preprocessor.


#define: Defines a macro or constant value.

Syntax: #define MACRO_NAME value

Example:
#define PI 3.14



#include: Includes the contents of a file.

Syntax: #include <filename> or #include "filename"

Example:
#include <stdio.h>



Other preprocessor directives:

#ifdef: Checks if a macro is defined.
#ifndef: Checks if a macro is not defined.
#endif: Ends an #if, #ifdef, or #ifndef.
#undef: Undefines a macro.
#pragma: Provides additional information to the compiler.

19. Write a C program for the following: there are two input files named first.dat and second.dat. The files are to be merged, i.e., copy the contents of first.dat and then second.dat to a new file named result.dat.
#include <stdio.h>

int main() {
    FILE *file1, *file2, *file3;
    char ch;
    
    file1 = fopen("first.dat", "r");
    if (file1 == NULL) {
        printf("Error opening first file.\n");
        return 1;
    }
    
    file2 = fopen("second.dat", "r");
    if (file2 == NULL) {
        printf("Error opening second file.\n");
        fclose(file1);
        return 1;
    }
    
    file3 = fopen("result.dat", "w");
    if (file3 == NULL) {
        printf("Error opening result file.\n");
        fclose(file1);
        fclose(file2);
        return 1;
    }
    
    // Copy content from first.dat
    while ((ch = fgetc(file1)) != EOF) {
        fputc(ch, file3);
    }
    
    // Copy content from second.dat
    while ((ch = fgetc(file2)) != EOF) {
        fputc(ch, file3);
    }
    
    printf("Contents merged into result.dat\n");
    
    fclose(file1);
    fclose(file2);
    fclose(file3);
    
    return 0;
}

20. Explain the command line arguments. What are the syntactic constructs followed in C?
Command Line Arguments:
Command line arguments allow users to pass parameters to the program at the time of execution. They are passed to the main() function.
Syntax:
int main(int argc, char *argv[])


argc: Argument count (number of arguments passed).
argv: Argument vector (an array of strings holding the arguments).

21. Write a C program to add two numbers using command line arguments.
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
    if (argc != 3) {
        printf("Please provide two numbers.\n");
        return 1;
    }
    
    int num1 = atoi(argv[1]);
    int num2 = atoi(argv[2]);
    
    printf("Sum: %d\n", num1 + num2);
    
    return 0;
}

22. What are macros in C? Write a program in C to calculate the area and perimeter of rectangle and circle using macros in C.
Macros in C:
Macros are preprocessor directives that define constant values or expressions.
Example:
#include <stdio.h>

#define PI 3.14
#define AREA_RECTANGLE(length, width) ((length) * (width))
#define PERIMETER_RECTANGLE(length, width) (2 * ((length) + (width)))
#define AREA_CIRCLE(radius) (PI * (radius) * (radius))
#define PERIMETER_CIRCLE(radius) (2 * PI * (radius))

int main() {
    float length = 5, width = 3, radius = 4;
    
    printf("Area of Rectangle: %.2f\n", AREA_RECTANGLE(length, width));
    printf("Perimeter of Rectangle: %.2f\n", PERIMETER_RECTANGLE(length, width));
    printf("Area of Circle: %.2f\n", AREA_CIRCLE(radius));
    printf("Perimeter of Circle: %.2f\n", PERIMETER_CIRCLE(radius));
    
    return 0;
}