A number is called perfect if the number is equal to the sum of its divisors (the number itself is not considered a divisor in this case).

```
#include <iostream>
using namespace std;
int main() {
int number, sum = 0;
cout << "Enter a number to check for perfect: ";
cin >> number;
for (int i = 1; i < number; i++) {
if (number % i == 0) {
sum = sum + i;
}
}
if (sum == number) {
cout << number << " is a perfect number";
}
else {
cout << number << " is not a perfect number";
}
return 0;
}
```

```
Enter a number to check for perfect: 28
28 is a perfect number
```

The first two lines include the `iostream`

library and the `std`

namespace, which provides access to the standard input and output streams (`cin`

and `cout`

) used in the code.

```
void checkPerfect(int max) {
int number, min = 1, i, sum = 0;
```

This is the definition of the function `checkPerfect`

. It takes an integer argument `max`

, which represents the upper bound for finding perfect numbers. Inside the function, several variables are declared:

`number`

: the number being tested to see if it’s a perfect number`min`

: the lower bound for finding perfect numbers, initialized to 1`i`

: a loop counter used in the inner loop to test the divisors of`number`

`sum`

: the sum of the divisors of`number`

, initialized to 0

```
for (number = min; number <= max; number++) {
sum = 0;
for (i = 1; i < number; i++) {
if (number % i == 0) {
sum = sum + i;
}
}
```

The first for loop iterates over the numbers from `min`

to `max`

. Inside the loop, `sum`

is reset to 0, and another for loop is used to test the divisors of `number`

. The inner loop uses the modulo operator (`%`

) to check if `i`

is a divisor of `number`

, and if so, adds `i`

to `sum`

.

```
if (sum == number) {
cout << number << " is a perfect number" << endl;
}
```

If the sum of the divisors of `number`

is equal to `number`

itself, then `number`

is considered a perfect number, and is output to the screen.

```
int main() {
int max;
cout << "Enter the upper bound to find perfect numbers: ";
cin >> max;
checkPerfect(max);
return 0;
}
```

The `main`

function is the entry point of the program. It first prompts the user to enter the upper bound for finding perfect numbers, then calls the `checkPerfect`

function with the user’s input as an argument. The `return 0;`

statement indicates that the program has executed successfully.

```
#include <iostream>
using namespace std;
void checkPerfect(int max) {
int number, min = 1, i, sum = 0;
for (number = min; number <= max; number++) {
sum = 0;
for (i = 1; i < number; i++) {
if (number % i == 0) {
sum = sum + i;
}
}
if (sum == number) {
cout << number << " is a perfect number" << endl;
}
}
}
int main() {
int max;
cout << "Enter the upper bound to find perfect numbers: ";
cin >> max;
checkPerfect(max);
return 0;
}
```

```
Enter the upper bound to find perfect numbers: 10000
6 is a perfect number
28 is a perfect number
496 is a perfect number
8128 is a perfect number
```

```
void checkPerfect(int max) {
int number, min = 1, i, sum = 0;
```

This is the definition of the function `checkPerfect`

. It takes an integer argument `max`

, which represents the upper bound for finding perfect numbers. Inside the function, several variables are declared:

`number`

: the number being tested to see if it’s a perfect number`min`

: the lower bound for finding perfect numbers, initialized to 1`i`

: a loop counter used in the inner loop to test the divisors of`number`

`sum`

: the sum of the divisors of`number`

, initialized to 0

```
for (number = min; number <= max; number++) {
sum = 0;
for (i = 1; i < number; i++) {
if (number % i == 0) {
sum = sum + i;
}
}
```

The first for loop iterates over the numbers from `min`

to `max`

. Inside the loop, `sum`

is reset to 0, and another for loop is used to test the divisors of `number`

. The inner loop uses the modulo operator (`%`

) to check if `i`

is a divisor of `number`

, and if so, adds `i`

to `sum`

.

```
if (sum == number) {
cout << number << " is a perfect number" << endl;
}
```

If the sum of the divisors of `number`

is equal to `number`

itself, then `number`

is considered a perfect number, and is output to the screen.

```
}
}
```

The end of the `checkPerfect`

function.

```
int main() {
int max;
cout << "Enter the upper bound to find perfect numbers: ";
cin >> max;
checkPerfect(max);
return 0;
}
```

The `main`

function is the entry point of the program. It first prompts the user to enter the upper bound for finding perfect numbers, then calls the `checkPerfect`

function with the user’s input as an argument. The `return 0;`

statement indicates that the program has executed successfully.

Login

Accessing this tutorial requires a login. Please enter your credentials below!