C program to find perfect numbers between 1 to n

Loop Exercises

C Basics C Programming Tutorial Basic C Exercises Bitwise Operator Exercises Conditional Operator Exercises If else Exercises Switch case Exercises Loop Exercises Star Patterns Number Patterns Functions Exercises Array Exercises String Exercises Pointer Exercises File handling Exercises Data Structures

• C Programming Exercises
• Basic C programming exercises
• Bitwise operator exercises
• Conditional operator exercises
• If else exercises
• Switch case exercises
• Loop and iteration exercises
• Star patterns exercises
• Number pattern exercises
• Functions and recursion exercises
• Array and Matrix exercises
• String exercises
• Pointer exercises
• Files handling exercises

C program to find perfect numbers between 1 to n

Write a C program to find all Perfect numbers between 1 to n. C program to find all perfect numbers between given range. How to generate all perfect numbers between given interval using loop in C programming. Logic to find all perfect numbers in a given range in C programming.

Required knowledge

Basic C programming, If statement, For loop, Nested loop

What is Perfect number?

Perfect number is a positive integer which is equal to the sum of its proper positive divisors.

For example: 6 is the first perfect number

Proper divisors of 6 are 1, 2, 3

Sum of its proper divisors = 1 + 2 + 3 = 6.

Hence 6 is a perfect number.

Logic to find all Perfect number between 1 to n

Step by step descriptive logic to find Perfect numbers from 1 to n.

1. Input upper limit from user to find Perfect numbers. Store it in a variable say end.
2. Run a loop from 1 to end, increment 1 in each iteration. The loop structure should look like for(i=1; i<=end; i++).
3. For each iteration inside loop print the value of i if it is a Perfect number.

Program to find all perfect numbers between 1 to n

 
/**
 * C program to print all Perfect numbers between 1 to n 
 */

#include <stdio.h>

int main()
{
    int i, j, end, sum;

    /* Input upper limit to print perfect number */
    printf("Enter upper limit: ");
    scanf("%d", &end);

    printf("All Perfect numbers between 1 to %d:\n", end);
    
    /* Iterate from 1 to end */
    for(i=1; i<=end; i++)
    {
        sum = 0;

        /* Check whether the current number i is Perfect number or not */
        for(j=1; j<i; j++)
        {
            if(i % j == 0)
            {
                sum += j;
            }
        }
 
        /* If the current number i is Perfect number */
        if(sum == i)
        {
            printf("%d, ", i);
        }
    }

    return 0;
}

Once, you got the logic to print perfect numbers from 1 to n. You can easily modify the logic to print perfect numbers in given range. I am writing the below program with little modification to print perfect numbers in given range.

Program to generate perfect numbers in given range

 
/**
 * C program to print all Perfect numbers between 1 to n 
 */

#include <stdio.h>

int main()
{
    int i, j, start, end, sum;

    /* Input lower and upper limit from user */
    printf("Enter lower limit: ");
    scanf("%d", &start);
    printf("Enter upper limit: ");
    scanf("%d", &end);

    printf("All Perfect numbers between %d to %d:\n", start, end);
    
    /* Iterate from start to end */
    for(i=start; i<=end; i++)
    {
        sum = 0;

        /* Check whether the current number i is Perfect number or not */
        for(j=1; j<i; j++)
        {
            if(i % j == 0)
            {
                sum += j;
            }
        }
 
        /* If the current number i is Perfect number */
        if(sum == i)
        {
            printf("%d, ", i);
        }
    }

    return 0;
}

Output

Enter lower limit: 1

Enter upper limit: 1000

All Perfect numbers between 1 to 1000:

6, 28, 496,

Follow @NEWSPAPERS_NEW

C Programming