1. program that calculates the area and circumference of a circle given its radius.

#include <stdio.h>
#include <math.h>

int main() {
    double radius, area, circumference;
    const double PI = 3.141592653589793; // Value of pi

    // Asking the user to enter the radius of the circle
    printf("Enter the radius of the circle: ");
    scanf("%lf", &radius);

    // Calculating area and circumference
    area = PI * pow(radius, 2); // Formula for area: pi * radius * radius
    circumference = 2 * PI * radius; // Formula for circumference: 2 * pi * radius

    // Displaying the calculated area and circumference
    printf("Area of the circle: %.2lf\\n", area);
    printf("Circumference of the circle: %.2lf\\n", circumference);

    return 0;
}

2. program that converts a temperature in Celsius to Fahrenheit and vice versa.

#include <stdio.h>

int main() {
    char choice;
    double temperature, convertedTemperature;

    // Asking the user for conversion choice
    printf("Enter 'C' to convert from Celsius to Fahrenheit or 'F' to convert from Fahrenheit to Celsius: ");
    scanf(" %c", &choice);

    // Checking the choice and performing the conversion
    if (choice == 'C' || choice == 'c') {
        // Converting from Celsius to Fahrenheit
        printf("Enter temperature in Celsius: ");
        scanf("%lf", &temperature);
        convertedTemperature = (temperature * 9 / 5) + 32;
        printf("Temperature in Fahrenheit: %.2lf\\n", convertedTemperature);
    } else if (choice == 'F' || choice == 'f') {
        // Converting from Fahrenheit to Celsius
        printf("Enter temperature in Fahrenheit: ");
        scanf("%lf", &temperature);
        convertedTemperature = (temperature - 32) * 5 / 9;
        printf("Temperature in Celsius: %.2lf\\n", convertedTemperature);
    } else {
        // Handling invalid choice
        printf("Invalid choice! Please enter 'C' or 'F'.\\n");
    }

    return 0;
}

3. program that checks if a given year is a leap year or not.

#include <stdio.h>

int main() {
    int year;

    // Asking the user to enter the year
    printf("Enter a year: ");
    scanf("%d", &year);

    // Checking if the year is a leap year
    if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
        printf("%d is a leap year.\\n", year);
    } else {
        printf("%d is not a leap year.\\n", year);
    }

    return 0;
}

4. program that generates a random number between 1 and 100 and asks the user to guess it.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main() {
    int numberToGuess, userGuess, attempts = 0;
    
    // Seed for the random number generator based on current time
    srand(time(NULL));
    
    // Generate a random number between 1 and 100
    numberToGuess = rand() % 100 + 1;
    
    printf("Welcome to the Number Guessing Game!\\n");
    
    do {
        // Ask the user to guess the number
        printf("Guess the number between 1 and 100: ");
        scanf("%d", &userGuess);
        
        // Increment the attempts counter
        attempts++;
        
        // Check if the guess is correct, too high, or too low
        if (userGuess < numberToGuess) {
            printf("Too low! Try again.\\n");
        } else if (userGuess > numberToGuess) {
            printf("Too high! Try again.\\n");
        } else {
            printf("Congratulations! You guessed the number %d in %d attempts.\\n", numberToGuess, attempts);
        }
    } while (userGuess != numberToGuess);
    
    return 0;
}

5. program that reverses a given string and prints it.

#include <stdio.h>
#include <string.h>

int main() {
    char inputString[100], reversedString[100];
    int i, j;

    // Asking the user to enter a string
    printf("Enter a string: ");
    scanf("%s", inputString);

    // Calculating the length of the input string
    int length = strlen(inputString);

    // Reversing the input string
    for (i = length - 1, j = 0; i >= 0; i--, j++) {
        reversedString[j] = inputString[i];
    }

    // Null-terminating the reversed string
    reversedString[j] = '\\0';

    // Printing the reversed string
    printf("Reversed string: %s\\n", reversedString);

    return 0;
}

6. program that counts the number of vowels and consonants in a given string.

#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main() {
    char inputString[100];
    int vowels = 0, consonants = 0, i;

    // Asking the user to enter a string
    printf("Enter a string: ");
    scanf("%s", inputString);

    // Calculating the length of the input string
    int length = strlen(inputString);

    // Counting vowels and consonants in the input string
    for (i = 0; i < length; i++) {
        // Converting the character to lowercase for case-insensitive comparison
        char ch = tolower(inputString[i]);
        
        // Checking if the character is a letter
        if (isalpha(ch)) {
            // Checking if the character is a vowel
            if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
                vowels++;
            } else {
                consonants++;
            }
        }
    }

    // Printing the count of vowels and consonants
    printf("Number of vowels: %d\\n", vowels);
    printf("Number of consonants: %d\\n", consonants);

    return 0;
}

7. program that writes a given string to a text file.

#include <stdio.h>
#include <stdlib.h>

int main() {
    FILE *file;
    char inputString[100];

    // Asking the user to enter a string
    printf("Enter a string: ");
    scanf("%s", inputString);

    // Opening the file in write mode
    file = fopen("output.txt", "w");

    // Checking if the file was opened successfully
    if (file == NULL) {
        printf("Error opening the file.\\n");
        return 1;
    }

    // Writing the input string to the file
    fprintf(file, "%s", inputString);

    // Closing the file
    fclose(file);

    printf("String has been written to the file 'output.txt'.\\n");

    return 0;
}

8. program that copies the contents of one text file to another.

#include <stdio.h>
#include <stdlib.h>

int main() {
    FILE *sourceFile, *destinationFile;
    char ch;

    // Opening the source file in read mode
    sourceFile = fopen("input.txt", "r");

    // Checking if the source file was opened successfully
    if (sourceFile == NULL) {
        printf("Error opening the source file.\\n");
        return 1;
    }

    // Opening the destination file in write mode
    destinationFile = fopen("output.txt", "w");

    // Checking if the destination file was opened successfully
    if (destinationFile == NULL) {
        printf("Error opening the destination file.\\n");
        fclose(sourceFile); // Close the source file before exiting
        return 1;
    }

    // Copying the contents of source file to destination file
    while ((ch = fgetc(sourceFile)) != EOF) {
        fputc(ch, destinationFile);
    }

    // Closing the files
    fclose(sourceFile);
    fclose(destinationFile);

    printf("Contents copied from 'input.txt' to 'output.txt'.\\n");

    return 0;
}

9. program that uses structures to store and display information about a student (name, roll number, marks, etc.).

#include <stdio.h>

// Define a structure to store student information
struct Student {
    char name[50];
    int rollNumber;
    float marks;
};

int main() {
    // Declare a structure variable of type Student
    struct Student student;

    // Input student information from the user
    printf("Enter student name: ");
    scanf("%s", student.name);
    printf("Enter roll number: ");
    scanf("%d", &student.rollNumber);
    printf("Enter marks: ");
    scanf("%f", &student.marks);

    // Display student information
    printf("\\nStudent Information\\n");
    printf("Name: %s\\n", student.name);
    printf("Roll Number: %d\\n", student.rollNumber);
    printf("Marks: %.2f\\n", student.marks);

    return 0;
}

10. program that uses pointers to swap the values of two variables.

#include <stdio.h>

void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

int main() {
    int num1, num2;

    // Input two numbers from the user
    printf("Enter first number: ");
    scanf("%d", &num1);
    printf("Enter second number: ");
    scanf("%d", &num2);

    // Print the numbers before swapping
    printf("Numbers before swapping: num1 = %d, num2 = %d\\n", num1, num2);

    // Call the swap function to swap the values using pointers
    swap(&num1, &num2);

    // Print the numbers after swapping
    printf("Numbers after swapping: num1 = %d, num2 = %d\\n", num1, num2);

    return 0;
}

11. program that prints the ASCII value of a given character.

#include <stdio.h>

int main() {
    char character;

    // Asking the user to enter a character
    printf("Enter a character: ");
    scanf("%c", &character);

    // Printing the ASCII value of the entered character
    printf("ASCII value of %c is %d\\n", character, character);

    return 0;
}

12. program that prints the prime numbers between 1 and 100.

#include <stdio.h>

int main() {
    int i, j, isPrime;

    // Iterate through numbers from 1 to 100
    printf("Prime numbers between 1 and 100 are: \\n");
    for (i = 2; i <= 100; i++) {
        isPrime = 1; // Assume the number is prime

        // Check if the number is divisible by any number from 2 to i-1
        for (j = 2; j <= i / 2; j++) {
            if (i % j == 0) {
                isPrime = 0; // Set isPrime to 0 if the number is divisible
                break;
            }
        }

        // If isPrime is still 1, then the number is prime, so print it
        if (isPrime == 1) {
            printf("%d ", i);
        }
    }

    printf("\\n");

    return 0;
}

13. program that prints the pattern of stars in a pyramid shape.

#include <stdio.h>

int main() {
    int rows, space, star;

    // Asking the user to enter the number of rows for the pyramid
    printf("Enter the number of rows: ");
    scanf("%d", &rows);

    // Outer loop for the number of rows
    for (int i = 1; i <= rows; i++) {
        // Print spaces before the stars
        for (space = 1; space <= rows - i; space++) {
            printf(" ");
        }

        // Print stars
        for (star = 1; star <= 2 * i - 1; star++) {
            printf("*");
        }

        // Move to the next line after each row is printed
        printf("\\n");
    }

    return 0;
}

14. program that prints the Pascal’s triangle up to a given number of rows.

#include <stdio.h>

int main() {
    int rows, coef = 1, space, i, j;

    // Asking the user to enter the number of rows for Pascal's triangle
    printf("Enter the number of rows for Pascal's triangle: ");
    scanf("%d", &rows);

    // Loop through each row
    for (i = 0; i < rows; i++) {
        // Print spaces before the numbers
        for (space = 1; space <= rows - i; space++) {
            printf("  ");
        }

        // Print the numbers in each row
        for (j = 0; j <= i; j++) {
            if (j == 0 || i == 0)
                coef = 1;
            else
                coef = coef * (i - j + 1) / j;

            printf("%4d", coef);
        }

        // Move to the next line after each row is printed
        printf("\\n");
    }

    return 0;
}

15. program that prints the current date and time using the time.h library.

#include <stdio.h>
#include <time.h>

int main() {
    // Get current time using time() function
    time_t currentTime;
    time(&currentTime);

    // Convert the current time to local time
    struct tm *localTime = localtime(&currentTime);

    // Print the current date and time
    printf("Current Date and Time: %s", asctime(localTime));

    return 0;
}

16. program that prints the number of words, characters, and lines in a given string.

#include <stdio.h>
#include <string.h>

int main() {
    char inputString[1000];
    int words = 0, characters = 0, lines = 0, i;

    // Asking the user to enter a string
    printf("Enter a string (press Enter and then Ctrl+D to end input):\\n");

    // Counting words, characters, and lines
    while (fgets(inputString, sizeof(inputString), stdin) != NULL) {
        lines++;

        for (i = 0; inputString[i] != '\\0'; i++) {
            characters++;

            // Check for words
            if (inputString[i] == ' ' || inputString[i] == '\\t' || inputString[i] == '\\n') {
                words++;
            }
        }
    }

    // Increment word count for the last word if it's not followed by space or newline
    if (i > 0 && inputString[i - 1] != ' ' && inputString[i - 1] != '\\t' && inputString[i - 1] != '\\n') {
        words++;
    }

    // Printing the counts
    printf("Number of words: %d\\n", words);
    printf("Number of characters: %d\\n", characters);
    printf("Number of lines: %d\\n", lines);

    return 0;
}

17. program that prints the square root of a given number using the math.h library.

#include <stdio.h>
#include <math.h>

int main() {
    double number;

    // Asking the user to enter a number
    printf("Enter a number: ");
    scanf("%lf", &number);

    // Calculating and printing the square root of the given number
    if (number >= 0) {
        double squareRoot = sqrt(number);
        printf("Square root of %.2lf is %.2lf\\n", number, squareRoot);
    } else {
        printf("Invalid input! Cannot calculate square root of a negative number.\\n");
    }

    return 0;
}

18. program that take user name and whishes happy birthday with blessing massage.

#include <stdio.h>
#include <string.h>

int main() {
    char userName[50];

    // Asking the user for their name
    printf("Enter your name: ");
    scanf("%s", userName);

    // Wishing the user a happy birthday with a blessing message
    printf("Happy Birthday, %s! 🎉🎂\\n", userName);
    printf("May your day be filled with joy and your year with success and happiness. Have a fantastic birthday!\\n");

    return 0;
}

19. program that calculates total percentage of marks.

#include <stdio.h>

int main() {
    int totalSubjects, totalMarks, obtainedMarks, totalObtainedMarks = 0;
    float percentage;

    // Asking the user for the total number of subjects
    printf("Enter the total number of subjects: ");
    scanf("%d", &totalSubjects);

    // Asking the user for the total marks for each subject
    printf("Enter the total marks for each subject: ");
    scanf("%d", &totalMarks);

    // Asking the user for the obtained marks in each subject and calculating total obtained marks
    for (int i = 1; i <= totalSubjects; i++) {
        printf("Enter the obtained marks in subject %d: ", i);
        scanf("%d", &obtainedMarks);
        totalObtainedMarks += obtainedMarks;
    }

    // Calculating the percentage
    percentage = ((float)totalObtainedMarks / (totalSubjects * totalMarks)) * 100;

    // Printing the total percentage of marks
    printf("Total Percentage of Marks: %.2f%%\\n", percentage);

    return 0;
}

20. program that calculates how old are you with date of birth.

#include <stdio.h>
#include <time.h>

int main() {
    int birthDay, birthMonth, birthYear;
    int currentDay, currentMonth, currentYear;
    int age;

    // Asking the user for their date of birth
    printf("Enter your date of birth (DD MM YYYY): ");
    scanf("%d %d %d", &birthDay, &birthMonth, &birthYear);

    // Getting the current date
    time_t t = time(NULL);
    struct tm *currentTime = localtime(&t);
    currentDay = currentTime->tm_mday;
    currentMonth = currentTime->tm_mon + 1; // Month starts from 0, so add 1
    currentYear = currentTime->tm_year + 1900; // Year is represented as years since 1900

    // Calculating the age
    age = currentYear - birthYear - 1; // Subtract 1 if the birthday hasn't occurred this year yet
    if (birthMonth < currentMonth || (birthMonth == currentMonth && birthDay <= currentDay)) {
        age++; // Add 1 if the birthday has occurred this year
    }

    // Printing the calculated age
    printf("You are %d years old.\\n", age);

    return 0;
}

C Assignment