Compute the natural logarithm of 2, by adding up to n terms in the series
1 - 1/2 + 1/3 - 1/4 + 1/5 -... 1/n
where n is a positive integer and input by user.

Source Code

#include<iostream>
using namespace std;

int main()
{
	int i,n,sign=-1;
	float sum=0;
	cout<<"Enter the value of n ";
	cin>>n;

	for(i=1;i<=n;i++)
	{
		sign *= -1;
		sum += sign*1.0/i;
	}
	cout<<"log 2 : "<<sum;

	
	return 0;
}


Output

SAMPLE RUN # 1

Enter the value of n 5
log 2 : 0.783333

SAMPLE RUN # 2

Enter the value of n 10000
log 2 : 0.693091