Write a C program to check perfect number?

Question

Write a C program to check if the given string is repeated substring or not.
ex
1: abcabcabc - yes (as abc is repeated.)
2: abcdabababababab - no

Answer 1

Hi try this function to check a number is perfect or not:

 bool CheckPrimeNumber(int number)
    {
        int  rem, sum = 0;
        for (int i = 1; i <=(int)(sqrt( (number )); i++)
        {
            if(! number % i)
            {
                sum = sum + i+number/i;
            }
        }
        if (sum == number)
            return true;
        else
            return false;
    }

Time Complexity : O(sqrt(n))

Answer 2

Perfect number, a positive integer that is equal to the sum of its proper divisors. The smallest perfect number is 6, which is the sum of 1, 2, and 3. Other perfect numbers are 28, 496, and 8,128.

#include<stdio.h>
void main()
{
int n,i,sum=0;
printf("Enter the number:");
scanf("%d",&n);

while(i<n)
{
    if(n%i==0)
           sum=sum+i;
          i++;
  }
  if(sum==n)
      printf("%d is a perfect number",i);
  else
      printf("%d is not a perfect number",i);

  return 0;
}

Comments

So many errors in the program,

Answer 3

#include <stdio.h>

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

    printf("Enter a Number\n");
    scanf("%d", &number);
    for (i = 1; i <= (number - 1); i++)
    {
        rem = number % i;
    if (rem == 0)
        {
            sum = sum + i;
        }
    }
    if (sum == number)
        printf("Entered Number is perfect number");
    else
        printf("Entered Number is not a perfect number");
    return 0;
}

Comments

Is O(n) a good approach for perfect number?