题解 | #计算一元二次方程#

#include<stdio.h>
#include<math.h>
#include<complex.h>
int main()
{
    float a,b,c,x1,x2,de,temp;
    while(scanf("%f %f %f",&a,&b,&c)!=EOF)
    {
        de=b*b-4*a*c;
        if(a==0)
        {
            printf("Not quadratic equation");
        }
        else
        {
            if(de>0)
            {
                x1=-sqrt((b*b-4*a*c)/(4*a*a))-b/(2*a);
                x2=sqrt((b*b-4*a*c)/(4*a*a))-b/(2*a);
                if(x1<x2)
                {
                    printf("x1=%.2f;x2=%.2f\n",x1,x2);
                }
                else
                {
                    temp=x1;
                    x1=x2;
                    x2=temp;
                    printf("x1=%.2f;x2=%.2f\n",x1,x2);
                }
            }
            if(de==0)
            {
                x1=-b/(2*a);
                printf("x1=x2=%.2f\n",x1);
            }
            if(de<0)
            {
                double e,r;
                e=-b/(2*a);
                r=sqrt(4*a*c-b*b)/(2*a);
                printf("x1=%.2lf-%.2lfi;x2=%.2f+%.2lfi\n",e,r,e,r);
            }
        }
    }
return 0;
}