近似计算

#include<stdio.h>
int main()
{
    double sum =0;
//    for(int i=0;;i++){
//        double term = 1.0/(2*i+1);
//        if(i%2==0) sum+=term;
//        else sum-=term;
//        if(term<1e-6) break;  
//    }

    int i=0;
    double term ;
    do
    {
        term = 1.0/(2*i+1);
        if(i%2==0) sum += term;
        else sum-= term;
        i++;
    }while(term >= 1e-6);
    printf("%.6f\n",sum);
    return 0;
}