else
            if(d >= 0){      
                        printf("x1 = %0.2f\n", ( -b + sqrt(d)) / (2 * a));
                        printf("x2 = %0.2f\n", ( -b - sqrt(d)) / (2 * a));
            }   
            else{
                        printf("x1 = %0.2f + %0.2fi\n", -b / (2 * a), sqrt(-d) / (2 * a));
                        printf("x2 = %0.2f - %0.2fi\n", -b / (2 * a), sqrt(-d) / (2 * a));
            }                                                                                                                                                                                                               这里的花括号去掉为什么出错

书上没有