题解 | #计算一元二次方程#

#include <math.h>
int main()
{
    float a,b,c;
    double x1,x2;
    while((scanf("%f%f%f",&a,&b,&c))!=EOF)
    {
        if(a==0.0)
            printf("Not quadratic equation");
        else
        {
            double s=b*b-4.0*a*c;
            if(s==0)
            {
                 float mp = -b + sqrt(s);
                if(mp == 0)
                {
                    printf("x1=x2=%.2f\n",mp);
                }else
                {
                    printf("x1=x2=%.2f\n",(-b+sqrt(s))/2.0/a);
                }          
            }else if(s>0)
            {
                x1=(-b - sqrt(s))/(2*a);
                x2=(-b + sqrt(s))/(2*a);
                printf("x1=%.2f;x2=%.2f\n",x1,x2);
            }else
            {
                 printf("x1=%.2f-%.2fi;x2=%.2f+%.2fi\n",-b/2/a,fabs(sqrt(-s)/2/a),-b/2/a,fabs(sqrt(-s)/2/a));\\fabs是对浮点数取绝对值！！
            }
        }
    }
        return 0;
}