问题描述:

I want to find sum of all divisors of a number i.e. if the number is 6 i want to have 1+2+3+6=12. My attempt to approach it is:

`#include <iostream>`

using namespace std;

int divisorsSum(int n){

int sum=0;

for (int i=1; i<=n; i++){

if(n%i==0)

i=sum+i;

}

return sum;

}

int main()

{

cout<<divisorsSum(6);

}

However surprisingly it does not work at all, it returns nothing and i am not able to figure out what is wrong with my code.

Thus the question is how to make it works?

BTW: There is no point in immediately down voting everything I am not an expert and yes i do make mistakes.

You have several issues in your code.

```
int i = i;
```

and `i`

is still not defined. You probably wanted `i = 1`

```
i = sum + i;
```

sum is not updated above. You probably wanted `sum += i`

You need to change your function `divisorsSum`

to use the following code:

```
int divisorsSum(int n)
{
int sum = 0;
for (int i = 1; i <= n; i++)
{
if(n % i == 0)
sum += i;
}
return sum;
}
```

```
for (int i=i; i<=n; i++)
```

Change the i=i to i = 1

```
int divisorsSum(int n){
int sum=0;
for (int i=1; i<=n; i++){
if(n%i==0)
sum+=i;
}
return sum;
}
```

- i starts from 1 and not i
- sum+=i and not i=sum+i

Maybe there are better algorithms of finding divisors of a number, but here is the correct version of your code.

```
int divisorsSum(int n){
int sum=0;
for (int i = 1; i <= n; ++i){
if(n % i == 0)
sum += i;
}
return sum;
}
```

And here is a little optimized version, if a `i`

is bigger than half of `n`

then `i`

cannot be a divisor of `n`

.

```
int divisorsSum(int n) {
int sum=0;
for (int i = n / 2; i >= 1; --i){
if(n % i == 0)
sum += i;
}
return sum;
}
```