这是个计算派的近似值的程序，为什么结果是4啊

#include<stdio.h>
int main()
{
double x;
int n;
for(n=1;;n++)
{
if((n%2)!=0)
{
x+=(1/(2n-1));
}
else
{
x-=(1/(2n-1));
}
if((2n+1)<(1e-8))
break;
}
printf("PI=%7.5f/n",4x);
}

#include<stdio.h>
int main()
{
    double x=0.0;
    int n;
    for (n = 1;; n++)
    {
        if ((n % 2) != 0)
        {
            x += ((double)1 / (double)(2*n - 1));
        }
        else
        {
            x -= ((double)1 / (double)(2*n - 1));
        }
        if ((2*n + 1) < (1e-8))
            break;
    }
    printf("PI=%7.5f\n", 4*x);
}