[Solved] - This is a very simple question but why am I always getting 1?

Question

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Consider the function sum(n)= 1+1/5 +1/10 +… +1/5n .
Write a nonrecursive version of sum(n). Use it to calculate sum(100).
Here's the code:

C++

#include <iostream>
using namespace std;
double suma (int   n);

void main ()
{ 
	int n;
	cout<<"Enter an integer n to calculate sum(n)= 1+1/5 +1/10 +… +1/5n  \n";
	cin>>n;
	cout<<"The sum ("<<n<<") is "<<suma(n)<<endl;
}
double suma (int a)
{
	int i, sum=0;
	for (i=1 ; i<=a; i++)
	{
		sum += (1/(5*i));
	}
	return sum+1;
}

Posted 28-Mar-10 11:00am

7mesho

Updated 28-Mar-10 11:16am

CPallini

v3

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Christian Graus · Accepted Answer · 2010-03-28T11:04:00

7mesho wrote:
sum += (1/(5*i));

1 divided by 5 is less than 1. As i increases, your number gets closer and closer to 0, and as it starts at .2, and because you're using int and not float or double, the values in the loop that get added to sum keep getting rounded down to 0. You are returning a double, but inside the method you're using int, you need to use double inside your method also.

If you learned how to use the debugger, and stepped through your code, this would have been apparent to you in no time.