5.5.cpp

c入门代码大全

/*求ax2+bx+c=0 的方程的姐*/
# include<stdio.h>
# include<math.h>
int main()
{
    float a,b,c,disc,x1,x2,r,i;
    scanf("%f%f%f",&a,&b,&c);
    if(a<=1e-6)
     printf("is not a quadratic\n");
     else
     {
         disc=b*b-4*a*c;
         if(fabs(disc)<=1e-6)
          printf("two equal roots:%f\n",-b/2*a);
          else
          if(disc>1e-6)
          {
            x1=(-b+sqrt(disc))/(2*a);
            x2=(-b-sqrt(disc))/(2*a);
            printf("%f%f",x1,x2);
          }
         else
         {
             r=-b/(2*a);
             i=sqrt(-disc)/(2*a);
             printf("has complex roots:");
             printf("%f+%f\n",r,i);
             printf("%f-%f\n",r,i);
             getchar();
             getchar();
         }
     }
}