C Programming Language || Hands On Coding

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

bool isPerfect(int num) {
 if (num <= 1) return false;
 int sum = 1;
 for (int i = 2; i * i <= num; i++) {
 if (num % i == 0) {
 sum += i;
 if (i * i != num) {
 sum += num / i;
 }
 }
 }
 return sum == num;
}

int main() {
 int number;
 scanf("%d", &number);
 if (isPerfect(number)) {
 printf("%d is a perfect number.\n", number);
 } else {
 printf("%d is not a perfect number.\n", number);
 }
 return 0;
}

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

int main() {
    int num, originalNum, remainder, n = 0;
    float result = 0.0;

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

    originalNum = num;

    while (originalNum != 0) {
        originalNum /= 10;
        ++n;
    }

    originalNum = num;

    while (originalNum != 0) {
        remainder = originalNum % 10;
        result += pow(remainder, n);
        originalNum /= 10;
    }

    if ((int)result == num)
        printf("%d is an Armstrong number.\n", num);
    else
        printf("%d is not an Armstrong number.\n", num);

    return 0;
}

#include <stdio.h>
#include <stdlib.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* generatePrimes(int n) {
 int* primes = (int*)malloc(n * sizeof(int));
 if (primes == NULL) return NULL;
 int count = 0;
 int num = 2;
 while (count < n) {
 if (isPrime(num)) {
 primes[count] = num;
 count++;
 }
 num++;
 }
 return primes;
}

int main() {
 int n = 10;
 int* primes = generatePrimes(n);
 if (primes != NULL) {
 printf("First %d prime numbers are: ", n);
 for (int i = 0; i < n; i++) {
 printf("%d ", primes[i]);
 }
 printf("\n");
 free(primes);
 }
 return 0;
}

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

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

void printPrimesInRange(int start, int end) {
 for (int i = start; i <= end; i++) {
 if (isPrime(i)) {
 printf("%d ", i);
 }
 }
 printf("\n");
}

int main() {
 int start, end;
 printf("Enter the start of the range: ");
 scanf("%d", &start);
 printf("Enter the end of the range: ");
 scanf("%d", &end);
 printf("Prime numbers in the range %d to %d are: ", start, end);
 printPrimesInRange(start, end);
 return 0;
}

#include <stdio.h>

int countDigits(int n) {
  int count = 0;
  if (n == 0) return 1;
  if (n < 0) n = -n;

  while (n > 0) {
    n = n - (n / 10) * 10;
    n = n / 10;
    count++;
  }
  return count;
}

int main() {
  int num = 12345;
  printf("Number of digits in %d: %d\n", num, countDigits(num));
  num = -987;
  printf("Number of digits in %d: %d\n", num, countDigits(num));
  num = 0;
   printf("Number of digits in %d: %d\n", num, countDigits(num));
  return 0;
}

#include <stdio.h>

int countDigits(int n) {
  int count = 0;
  if (n == 0) return 1;
  while (n > 0) {
    n = n - (n / 10) * 10; 
    n = n / 10;
    count++;
  }
  return count;
}

int main() {
  int num = 12345;
  printf("Number of digits in %d: %d\n", num, countDigits(num));
  return 0;
}

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

int main() {
    int num, originalNum, remainder, n = 0, result = 0;

    scanf("%d", &num);
    originalNum = num;

    while (originalNum != 0) {
        originalNum /= 10;
        ++n;
    }

    originalNum = num;

    while (originalNum != 0) {
        remainder = originalNum % 10;
        result += pow(remainder, n);
        originalNum /= 10;
    }

    if (result == num)
        printf("Armstrong");
    else
        printf("Not Armstrong");

    return 0;
}

#include <stdio.h>
#include <stdlib.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* generatePrimes(int n) {
 int* primes = (int*)malloc(n * sizeof(int));
 if (primes == NULL) return NULL;
 int count = 0;
 int num = 2;
 while (count < n) {
 if (isPrime(num)) {
 primes[count] = num;
 count++;
 }
 num++;
 }
 return primes;
}

int main() {
 int n = 10;
 int* primes = generatePrimes(n);
 if (primes != NULL) {
 printf("First %d prime numbers are: ", n);
 for (int i = 0; i < n; i++) {
 printf("%d ", primes[i]);
 }
 printf("\n");
 free(primes);
 }
 return 0;
}

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

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

void printPrimesInRange(int start, int end) {
    for (int i = start; i <= end; i++) {
        if (isPrime(i)) {
            printf("%d ", i);
        }
    }
    printf("\n");
}

int main() {
    int start, end;
    scanf("%d %d", &start, &end);
    printPrimesInRange(start, end);
    return 0;
}