Adding consecutive numbers using a loop

[okay412]

I'm having some trouble with this program:

#include <iostream>

using namespace std;

int main()

{

int n = 0;		//counter
int sum = 1;	//output
cout << "Please enter a number" << endl;
cin >> sum;
while ( n <= 6 )
{

    sum=n + sum;

    n++;
cout << "sum is" << sum << endl;
}

//cout << "sum is" << sum << endl;

return 0;
}

The final number should be 21 (1+2+3+4+5+6) if the number 1 is input. However, I'm getting 22. I'm not sure where I went wrong. Any help is appreciated, thanks!

[TarikNeaj]

If you input the number 1. Then the number 1 will be counted twice. it Would become -

(1+1+2+3+4+5+6)

Because sum would start at 1, then you would add 1 (because n would become 1).

It should really look like this -

(0+1+2+3+4+5+6) // notice the 0

So sum should be inputted as 0.

[okay412]

when int sum = 0, I still get 22.

[TarikNeaj]

It doesnt matter what you initialize sum to, you can put int sum = 355; and it wouldnt change a thing, because in the next line of code you are going to overwrite it with your own user-inputted value. There you need to input 0.

Try this -

#include <iostream>

using namespace std;

int main()

{

int n = 0;		//counter
int sum = 0;	//output

while ( n <= 6 )
{

    sum=n + sum;

    n++;
cout << "sum is" << sum << endl;
}

//cout << "sum is" << sum << endl;

return 0;
}

[AbstractionAnon]

When I input 0, I get 21 as expected:

Please enter a number
0
sum is0
sum is1
sum is3
sum is6
sum is10
sum is15
sum is21

edit: Your post seems to imply you changed line 10. As TarikNeaj pointed out, the value you initialize sum to makes no difference since you overwrite it with your cin statement.