题解 | #计算一元二次方程#

#include <stdio.h>
#include<math.h>
int main() {
    float a, b, c;
    while (scanf("%f%f%f", &a, &b, &c) != EOF) {
        float der = b * b - 4 * a * c;
        if (a == 0)
            printf("Not quadratic equation");
        else {
            if (der == 0)
                printf("x1=x2=%.2f\n", b / -(2 * a * 1.0) + 0);//必须加+0不然会输出-0
            else if (der > 0)
                printf("x1=%.2f;x2=%.2f\n", (-b - (float)sqrt(der)) / (2 * a * 1.0),
                       (-b + (float)sqrt(der)) / (2 * a * 1.0));
            else
                printf("x1=%.2f-%.2fi;x2=%.2f+%.2fi\n", -b / (2 * a), sqrt(-der) / (2.0 * a),
                       -b / (2.0 * a), sqrt(-der) / (2.0 * a));
        }
    }
    return 0;
}