C language practice questions: find the value of 1-1/2+1/3-1/4+... -1/100

/*******************************************

    Find the value of 1-1/2+1/3-1/4+... -1/100

*******************************************/
#include <stdio.h>

int main(void)
{
    int i = 1;
    float sum = 0;

    while(i <= 100)
    {
        if(i % 2 == 0)
        {
            sum -=1/(i++*1.0);
        }else
        {
            sum +=1/(i++*1.0);
        }
    }
    printf("%f\n",sum);
}