C Exercises: Perfect numbers in a given range

Last update on October 24 2025 12:09:23 (UTC/GMT +8 hours)

10. Perfect Numbers in Range Function Variants

Write a program in C to print all perfect numbers in a given range using the function.

Pictorial Presentation:

C Exercises: Perfect numbers in a given range

Sample Solution:

C Code:

#include <stdio.h>
 /* Function declarations */
int checkPerfect(int n1);
void PerfectNumbers(int stLimit, int enLimit);

int main()
{
    int stLimit, enLimit;
	printf("\n\n Function : perfect numbers in a given range :\n");
	printf("--------------------------------------------------\n");     
    printf(" Input lowest search limit of perfect numbers : ");
    scanf("%d", &stLimit);
    printf(" Input highest search limit of  perfect numbers : ");
    scanf("%d", &enLimit);
     
    printf("\n The perfect numbers between %d to %d are : \n", stLimit, enLimit);
    PerfectNumbers(stLimit, enLimit);
    printf("\n\n"); 
    return 0;
}
// Checks whether the given number is perfect or not.

int checkPerfect(int n1)
{
    int i, sum;
     
    sum = 0;
    for(i=1; i<n1; i++)
    {
        if(n1 % i == 0)
        {
            sum += i;
        }
    }
// If sum of proper positive divisors equals to given number 
// then the number is perfect number
    if(sum == n1)
        return 1;
    else
        return 0;
}

void PerfectNumbers(int stLimit, int enLimit)
{
    /* print perfect numbers from start to end */
    while(stLimit <= enLimit)
    {
        if(checkPerfect(stLimit))
        {
            printf(" %d  ", stLimit);
        }
        stLimit++;
    }   
}

Sample Output:

 Function : perfect numbers in a given range :
--------------------------------------------------
 Input lowest search limit of perfect numbers : 1
 Input highest search limit of  perfect numbers : 100

 The perfect numbers between 1 to 100 are :
 6   28

Flowchart:

Flowchart: Perfect numbers in a given range

For more Practice: Solve these Related Problems:

Write a C program to count the number of perfect numbers in a given range using a function.
Write a C program to return an array of perfect numbers found within a specified range via a function.
Write a C program to check for perfect numbers by calculating the sum of proper divisors inside a function and printing each found.
Write a C program to optimize the search for perfect numbers in a range using memoization in the divisor-sum function.

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