题解 | #计算一元二次方程#

#include <stdio.h>
#include <math.h>
int main() {
    double a, b, c;
    double x1 = 0.00, x2 = 0.00; //方程的根
    double x =0.00,y=0.00;//x表示实部，y表示虚部
    while (scanf("%lf %lf %lf", &a, &b, &c) != EOF) {
        if (a == 0) {
            printf("Not quadratic equation\n");
        } else {
            if (b * b - 4 * a * c == 0) {  //等于零单实根
                if (b==0&&c==0) {
                    printf("x1=x2=0.00\n");
                } else {
                x1 = -1.0 * b / (2.0 * a);
                printf("x1=x2=%.2lf\n", x1);
                }
            } else if (b * b - 4 * a * c > 0) { //大于零双实根
                x1 = (-b - sqrt(b * b - 4 * a * c)) / 2.0 / a;
                x2 = (-b + sqrt(b * b - 4 * a * c)) / 2.0 / a;
                printf("x1=%.2lf;x2=%.2lf\n", x1, x2);
            } else {      //小于零虚根
                x = -b/(2.0*a);
                y = sqrt(4 * a * c - b * b)/(2.0*a);
                printf("x1=%.2lf-%.2lfi;x2=%.2lf+%.2lfi\n",x,y,x,y );
            }
        }
    }
   return 0;
}