编写C++程序，用公π/4=1-1/3+1/5-1/7+⋯求π式的近似值，直到最后一项的绝对值小于10^(-6)为止。

#include <stdio.h>

int main() {
    double pi = 0.0;
    int n = 1;
    double term = 1.0;
    while (term >= 1e-6) {
        pi += term;
        n += 2;
        term = (n % 4 == 1 ? 1 : -1) * 1.0 / n;
    }
    pi *= 4;
    printf("pi = %f\n", pi);
    return 0;
}