C Exercises: Find perfect numbers within a given number of range

C For Loop: Exercise-28 with Solution

Write a C program to find the 'Perfect' numbers within a given number of ranges.

Sample Solution:

C Code:

/* 
   Perfect number is a positive number which sum of all positive divisors excluding 
   that number is equal to that number. For example 6 is perfect number since divisor of 6 are 1, 2 and 3.  
   Sum of its divisor is 1 + 2 + 3 = 6
*/

#include <stdio.h> // Include the standard input/output header file.

int  main(){
  int n, i, sum; // Declare variables for the number being checked, loop control, and sum.
  int mn, mx;    // Variables for the starting and ending range of numbers.

  printf("Input the starting range or number : "); // Prompt the user for the starting range.
  scanf("%d", &mn); // Read the starting range from the user.

  printf("Input the ending range of number : "); // Prompt the user for the ending range.
  scanf("%d", &mx); // Read the ending range from the user.

  printf("The Perfect numbers within the given range : "); // Print a message indicating perfect numbers are being displayed.

  for(n = mn; n <= mx; n++){ // Loop through the numbers in the specified range.
    i = 1; // Initialize the divisor.
    sum = 0; // Initialize the sum of divisors.

    while(i < n){ // While the divisor is less than the number being checked.
      if(n % i == 0) // If 'i' is a divisor of 'n'.
           sum = sum + i; // Add 'i' to the sum.

      i++; // Increment the divisor.
    }

    if(sum == n) // If the sum of divisors is equal to the original number.
      printf("%d ", n); // Print the perfect number.
  }

  printf("\n"); // Print a new line for better formatting.
   return 0;  // Indicate that the program has executed successfully.
}

Sample Output:

Input the starting range or number : 1                                                                        
Input the ending range of number : 50                                                                         
The Perfect numbers within the given range : 6 28

Flowchart:

C Programming Code Editor:

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