C Programming Language || Hands On Coding

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💻 Function to Reverse a Number

#include <stdio.h>

int reverseNumber(int num) {
    int reversed = 0;
    while (num != 0) {
        int remainder = num % 10;
        reversed = reversed * 10 + remainder;
        num /= 10;
    }
    return reversed;
}

int main() {
    int number;

    printf("Enter an integer: ");
    scanf("%d", &number);

    int reversedNumberResult = reverseNumber(number);

    printf("Reversed Number: %dn", reversedNumberResult);

    return 0;
}

📤 Output:

Input: 12345
Output: Reversed Number: 54321

Input: 100
Output: Reversed Number: 1

Input: -123
Output: Reversed Number: -321

Input: 0
Output: Reversed Number: 0

💻 Function to Print Fibonacci Series

#include <stdio.h>

void printFibonacci(int n) {
    int first = 0, second = 1, next;

    printf("Fibonacci Series: ");

    for (int i = 0; i < n; i++) {
        printf("%d ", first);
        next = first + second;
        first = second;
        second = next;
    }
    printf("n");
}

int main() {
    int num;

    printf("Enter the number of terms for Fibonacci Series: ");
    scanf("%d", &num);

    printFibonacci(num);

    return 0;
}

📤 Output:

Input: 10
Output: Enter the number of terms for Fibonacci Series: Fibonacci Series: 0 1 1 2 3 5 8 13 21 34

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💻 Function to Calculate LCM

#include <stdio.h>

int findLCM(int a, int b) {
    int max = (a > b) ? a : b;
    while (1) {
        if (max % a == 0 && max % b == 0) {
            return max;
        }
        max++;
    }
}

int main() {
    int num1, num2, lcm;

    printf("Enter two positive integers: ");
    scanf("%d %d", &num1, &num2);

    lcm = findLCM(num1, num2);

    printf("LCM of %d and %d is %dn", num1, num2, lcm);

    return 0;
}

📤 Output:

Input: 12 18
Output: Enter two positive integers: LCM of 12 and 18 is 36

Input: 5 7
Output: Enter two positive integers: LCM of 5 and 7 is 35

Input: 24 36
Output: Enter two positive integers: LCM of 24 and 36 is 72

💻 Function to Calculate GCD/HCF (Euclidean Algorithm)

#include <stdio.h>

int gcd(int a, int b) {
    while (b != 0) {
        int temp = b;
        b = a % b;
        a = temp;
    }
    return a;
}

int main() {
    int num1, num2;

    printf("Enter two integers: ");
    scanf("%d %d", &num1, &num2);

    int result = gcd(num1, num2);

    printf("GCD of %d and %d is %dn", num1, num2, result);

    return 0;
}

📤 Output:

Input: 48 18
Output: Enter two integers: GCD of 48 and 18 is 6
Input: 1071 462
Output: Enter two integers: GCD of 1071 and 462 is 21
Input: 12 18
Output: Enter two integers: GCD of 12 and 18 is 6
Input: 5 7
Output: Enter two integers: GCD of 5 and 7 is 1
Input: 25 15
Output: Enter two integers: GCD of 25 and 15 is 5

💻 Function to Calculate nPr (Permutations)

#include <stdio.h>

long long factorial(int n) {
    long long fact = 1;
    for (int i = 1; i <= n; i++) {
        fact *= i;
    }
    return fact;
}

long long nPr(int n, int r) {
    if (r > n) {
        return 0;
    }
    return factorial(n) / factorial(n - r);
}

int main() {
    int n, r;
    printf("Enter the value of n: ");
    scanf("%d", &n);
    printf("Enter the value of r: ");
    scanf("%d", &r);

    long long result = nPr(n, r);

    printf("nPr (%d, %d) = %lldn", n, r, result);

    return 0;
}

📤 Output:

Input: 5
Input: 2
Output: nPr (5, 2) = 20

Input: 7
Input: 7
Output: nPr (7, 7) = 5040

Input: 10
Input: 3
Output: nPr (10, 3) = 720

Input: 4
Input: 5
Output: nPr (4, 5) = 0

💻 Function to Calculate nCr (Combinations)

#include <stdio.h>

int factorial(int n) {
    int fact = 1;
    for (int i = 1; i <= n; i++) {
        fact *= i;
    }
    return fact;
}

int nCr(int n, int r) {
    if (r < 0 || r > n) {
        return 0;
    }
    return factorial(n) / (factorial(r) * factorial(n - r));
}

int main() {
    int n, r;

    printf("Enter the value of n: ");
    scanf("%d", &n);

    printf("Enter the value of r: ");
    scanf("%d", &r);

    printf("nCr(%d, %d) = %dn", n, r, nCr(n, r));

    return 0;
}

📤 Output:

Input: 5
Input: 2
Output: nCr(5, 2) = 10

Input: 7
Input: 0
Output: nCr(7, 0) = 1

Input: 4
Input: 4
Output: nCr(4, 4) = 1

Input: 6
Input: 3
Output: nCr(6, 3) = 20

Input: 5
Input: -1
Output: nCr(5, -1) = 0

Input: 5
Input: 6
Output: nCr(5, 6) = 0

💻 Function to Check Armstrong Number

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

int isArmstrong(int num) {
  int originalNum, remainder, n = 0;
  double result = 0.0;

  originalNum = num;

  // Count number of digits
  while (originalNum != 0) {
    originalNum /= 10;
    ++n;
  }

  originalNum = num;

  // Calculate sum of digits raised to the power n
  while (originalNum != 0) {
    remainder = originalNum % 10;
    result += pow(remainder, n);
    originalNum /= 10;
  }

  // Check if number is Armstrong
  if ((int)result == num) {
    return 1; // True
  } else {
    return 0; // False
  }
}

int main() {
  int number;

  printf("Enter an integer: ");
  scanf("%d", &number);

  if (isArmstrong(number)) {
    printf("%d is an Armstrong number.n", number);
  } else {
    printf("%d is not an Armstrong number.n", number);
  }

  return 0;
}

📤 Output:

Input: 153
Output: 153 is an Armstrong number.

Input: 120
Output: 120 is not an Armstrong number.

Input: 370
Output: 370 is an Armstrong number.

Input: 1634
Output: 1634 is an Armstrong number.

Input: 123
Output: 123 is not an Armstrong number.

💻 Function to Check Palindrome

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

int isPalindrome(char str[]) {
    int left = 0;
    int right = strlen(str) - 1;

    while (left < right) {
        if (str[left] != str[right]) {
            return 0;
        }
        left++;
        right--;
    }
    return 1;
}

int main() {
    char inputString[100];

    printf("Enter a string: ");
    scanf("%s", inputString);

    if (isPalindrome(inputString)) {
        printf(""%s" is a palindrome.n", inputString);
    } else {
        printf(""%s" is not a palindrome.n", inputString);
    }

    return 0;
}

📤 Output:

Input: madam
Output: "madam" is a palindrome.

Input: hello
Output: "hello" is not a palindrome.

Input: A man a plan a canal Panama
Output: "A" is not a palindrome.

💻 Function to Calculate Factorial

#include <stdio.h>

int factorial(int n) {
  if (n == 0) {
    return 1;
  } else {
    return n * factorial(n - 1);
  }
}

int main() {
  int num;
  printf("Enter a non-negative integer: ");
  scanf("%d", &num);

  if (num < 0) {
    printf("Factorial is not defined for negative numbers.n");
  } else {
    int result = factorial(num);
    printf("Factorial of %d = %dn", num, result);
  }
  return 0;
}

📤 Output:

Input: 5
Output: Enter a non-negative integer: Factorial of 5 = 120

Input: 0
Output: Enter a non-negative integer: Factorial of 0 = 1

Input: -2
Output: Enter a non-negative integer: Factorial is not defined for negative numbers.

💻 Function to Check Prime Number

#include <stdio.h>
#include <stdbool.h>

bool isPrime(int n) {
    if (n <= 1) return false;
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0) return false;
    }
    return true;
}

int main() {
    int num;
    printf("Enter a number: ");
    scanf("%d", &num);

    if (isPrime(num)) {
        printf("%d is a prime number.n", num);
    } else {
        printf("%d is not a prime number.n", num);
    }

    return 0;
}

📤 Output:

Input: 7
Output: 7 is a prime number.

Input: 12
Output: 12 is not a prime number.

Input: 1
Output: 1 is not a prime number.

Input: 0
Output: 0 is not a prime number.

Input: -5
Output: -5 is not a prime number.

🔧 Functions

💻 Game Character Movement Simulation

#include <stdio.h>

int main() {
  int x = 0, y = 0;
  char move;

  do {
    printf("Current position: (%d, %d)n", x, y);
    printf("Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): ");
    scanf(" %c", &move);

    switch (move) {
      case 'w':
        y++;
        break;
      case 'a':
        x--;
        break;
      case 's':
        y--;
        break;
      case 'd':
        x++;
        break;
      case 'q':
        printf("Quitting the game.n");
        break;
      default:
        printf("Invalid move. Try again.n");
    }
  } while (move != 'q');

  return 0;
}

📤 Output:

Current position: (0, 0)
Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): Input: w
Output: Current position: (0, 1)
Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): Input: a
Output: Current position: (-1, 1)
Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): Input: s
Output: Current position: (-1, 0)
Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): Input: d
Output: Current position: (0, 0)
Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): Input: x
Output: Invalid move. Try again.
Current position: (0, 0)
Enter move (w/a/s/d - wasd keys for up/left/down/right, q to quit): Input: q
Output: Quitting the game.

💻 Temperature Conversion Menu

#include <stdio.h>

int main() {
    int choice;
    float temp, converted_temp;

    do {
        printf("Temperature Conversion Menu:n");
        printf("1. Celsius to Fahrenheitn");
        printf("2. Fahrenheit to Celsiusn");
        printf("3. Exitn");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                printf("Enter temperature in Celsius: ");
                scanf("%f", &temp);
                converted_temp = (temp * 9 / 5) + 32;
                printf("Temperature in Fahrenheit: %.2fn", converted_temp);
                break;
            case 2:
                printf("Enter temperature in Fahrenheit: ");
                scanf("%f", &temp);
                converted_temp = (temp - 32) * 5 / 9;
                printf("Temperature in Celsius: %.2fn", converted_temp);
                break;
            case 3:
                printf("Exiting...n");
                break;
            default:
                printf("Invalid choice. Please try again.n");
        }
    } while (choice != 3);

    return 0;
}

📤 Output:

Temperature Conversion Menu:
1. Celsius to Fahrenheit
2. Fahrenheit to Celsius
3. Exit
Enter your choice: Input: 1
Enter temperature in Celsius: Input: 25
Output: Temperature in Fahrenheit: 77.00
Temperature Conversion Menu:
1. Celsius to Fahrenheit
2. Fahrenheit to Celsius
3. Exit
Enter your choice: Input: 2
Enter temperature in Fahrenheit: Input: 98.6
Output: Temperature in Celsius: 37.00
Temperature Conversion Menu:
1. Celsius to Fahrenheit
2. Fahrenheit to Celsius
3. Exit
Enter your choice: Input: 3
Output: Exiting...

💻 Simple ATM Machine Simulation

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

int main() {
    int option;
    float balance = 1000.0;
    float amount;

    do {
        printf("ATM Menu:n");
        printf("1. Check Balancen");
        printf("2. Depositn");
        printf("3. Withdrawn");
        printf("4. Exitn");
        printf("Enter your option: ");
        scanf("%d", &option);

        switch (option) {
            case 1:
                printf("Your balance is: %.2fn", balance);
                break;
            case 2:
                printf("Enter amount to deposit: ");
                scanf("%f", &amount);
                if (amount > 0) {
                    balance += amount;
                    printf("Deposit successful. New balance: %.2fn", balance);
                } else {
                    printf("Invalid amount.n");
                }
                break;
            case 3:
                printf("Enter amount to withdraw: ");
                scanf("%f", &amount);
                if (amount > 0 && amount <= balance) {
                    balance -= amount;
                    printf("Withdrawal successful. New balance: %.2fn", balance);
                } else {
                    printf("Insufficient funds or invalid amount.n");
                }
                break;
            case 4:
                printf("Exiting ATM. Thank you!n");
                break;
            default:
                printf("Invalid option. Please try again.n");
        }
    } while (option != 4);

    return 0;
}

📤 Output:

ATM Menu:
1. Check Balance
2. Deposit
3. Withdraw
4. Exit
Enter your option: Input: 1
Output: Your balance is: 1000.00
ATM Menu:
1. Check Balance
2. Deposit
3. Withdraw
4. Exit
Enter your option: Input: 2
Output: Enter amount to deposit: Input: 200
Output: Deposit successful. New balance: 1200.00
ATM Menu:
1. Check Balance
2. Deposit
3. Withdraw
4. Exit
Enter your option: Input: 3
Output: Enter amount to withdraw: Input: 500
Output: Withdrawal successful. New balance: 700.00
ATM Menu:
1. Check Balance
2. Deposit
3. Withdraw
4. Exit
Enter your option: Input: 3
Output: Enter amount to withdraw: Input: 800
Output: Insufficient funds or invalid amount.
ATM Menu:
1. Check Balance
2. Deposit
3. Withdraw
4. Exit
Enter your option: Input: 4
Output: Exiting ATM. Thank you!

💻 Password Validation

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

int main() {
  char password[50];
  int isValid = 0;

  do {
    printf("Enter your password: ");
    scanf("%s", password);

    if (strlen(password) >= 8) {
      isValid = 1;
      printf("Password accepted!n");
    } else {
      printf("Password must be at least 8 characters long.n");
      printf("Please try again.n");
    }
  } while (isValid == 0);

  return 0;
}

📤 Output:

Input: pass
Output: Password must be at least 8 characters long.
Output: Please try again.
Input: password123
Output: Password accepted!

💻 Sum of Numbers until Negative is Entered

#include <stdio.h>

int main() {
  int number, sum = 0;

  do {
    printf("Enter a number (negative to stop): ");
    scanf("%d", &number);

    if (number >= 0) {
      sum += number;
    }
  } while (number >= 0);

  printf("Sum of positive numbers entered: %dn", sum);

  return 0;
}

📤 Output:

Input: 10
Input: 5
Input: 2
Input: -1
Output: Sum of positive numbers entered: 17

💻 Continue until User Says 'No'

#include <stdio.h>

int main() {
    char answer;

    do {
        printf("Do you want to continue? (y/n): ");
        scanf(" %c", &answer);

        if (answer == 'y') {
            printf("Continuing...n");
        } else if (answer == 'n') {
            printf("Exiting...n");
        } else {
            printf("Invalid input. Please enter 'y' or 'n'.n");
        }

    } while (answer != 'n');

    return 0;
}

📤 Output:

Input: y
Output: Do you want to continue? (y/n): Continuing...
Input: z
Output: Do you want to continue? (y/n): Invalid input. Please enter 'y' or 'n'.
Input: Y
Output: Do you want to continue? (y/n): Invalid input. Please enter 'y' or 'n'.
Input: n
Output: Do you want to continue? (y/n): Exiting...

💻 Input Validation for Range

#include <stdio.h>

int main() {
  int number;
  int lower_bound = 10;
  int upper_bound = 20;

  do {
    printf("Enter a number between %d and %d: ", lower_bound, upper_bound);
    scanf("%d", &number);

    if (number < lower_bound || number > upper_bound) {
      printf("Invalid input. Please enter a number within the specified range.n");
    }
  } while (number < lower_bound || number > upper_bound);

  printf("You entered: %dn", number);

  return 0;
}

📤 Output:

Input: 5
Output: Enter a number between 10 and 20: 5
Invalid input. Please enter a number within the specified range.
Input: 25
Output: Enter a number between 10 and 20: 25
Invalid input. Please enter a number within the specified range.
Input: 15
Output: Enter a number between 10 and 20: 15
You entered: 15