输入一个正实数eps，计算并输出下式的值，直到最后一项的绝对值小于eps。 s=1-1/5+1/9-1/13+1/17-1/21..

#include#includevoid main(){ int i; double eps, n, s, j; printf("input eps(eps>0)=:"); i = 0; s = 0; j = 1; scanf("%lf", &eps); do { n = j / (4 * i + 1); j = j * -1; s += n; i++; } while (fabs(n) > eps); printf("s=%f