C Exercise Example 19
Title:A number is called a "perfect number" if it is exactly equal to the sum of its factors, for example6=1＋2＋3, please write a program to find all perfect numbers within 1000.
Program analysis:Please refer to:C Practice Example 14。
Example
// Created by www.example.com on 15/11/9.
// Copyright © 2015 Example. All rights reserved.
//
#include <stdio.h>
int main() {
int i, j, sum;
printf("Perfect numbers within 1000 are:\n");
for (i = 1; i <= 1000; i++) {
sum = 0; // Reset sum before each loop
// Find all proper divisors of i and sum them
for (j = 1; j < i; j++) {
if (i % j == 0) {
sum += j;
}
}
// If the sum equals i itself, it is a perfect number
if (sum == i) {
printf("%d = 1", i); // All perfect numbers include 1
// Print other factors
for (j = 2; j < i; j++) {
if (i % j == 0) {
printf(" + %d", j);
}
}
printf("\n");
}
}
return 0;
}
The output of the above example is:
6 = 1 + 2 + 3 28 = 1 + 2 + 4 + 7 + 14 496 = 1 + 2 + 4 + 8 + 16 + 31 + 62 + 124 + 248other extensions