C :

#include<stdio.h>
int main()
{
	int sign=1;
	double deno=2.0,sum=1.0,term;
	while(deno<=100)
	{
		sign=-sign;
		term=sign/deno;
		sum=sum+term;
		deno=deno+1;
	}
	printf("%.8f\n",sum);
		
		return 0;
}

C++ :

#include<stdio.h>
int main()
{
  int sign=1;
  double deno=2.0,sum=1.0,term;
  while(deno<=100)
  {
    sign=-sign;
    term=sign/deno;
    sum=sum+term;
    deno=deno+1;
  }
  printf("%.8f\n",sum);
  return 0;
}