本人是个菜鸟 求解这个程序为什么编译不了 谢谢

#include "stdio.h"
#include "math.h"
void solv_quadr_equa(float a,float b, float c)
{ if (a==0.0) if (b=0.0)
printf ( "no answer due to input error\n");
else
printf ("the signgle root is %f\n",-c/b);
else
{
double disc ,twoa, term1,term2;
disc=b*b-4*a*c;
twoa=2*a;
term1=-b/twoa;
term2=sqrt(fabs(disc))/twoa;
if(disc<0.0)
printf("complex root:\n real part=%f,imag part=%f\n",term1,term2);
else
printf ("real root:\n root1=%f,root2=%f\n",term1+term2,term1-term2);
}
}
void main()
{ float x,y,z,void solv_quadr_equa(float x,float y,float z);
printf ("please input 3 number:");
scanf("%f%f%f",&x,&y,&z);
printf ("solv_quadr_equa(%f%f%f)=%f%f%f\n",x,y,z,void solv_quadr_equa (x,y,z));
}