用C语言编写程序实现一元二次方程的解？

#include <math.h>
main()
{
int z=0;
while(z==0)
{
float a,b,c,disc,x1,x2;
printf("input a,b,c:");
scanf("%f,%f,%f",&a,&b,&c);
disc=b*b-4*a*c;
if(disc>=0)z=1;
}
x1=(-b+sqrt(disc))/(2*a);
x2=(-b-sqrt(disc))/(2*a);
printf("\nx1=%6.2f x2=%6.2f\n",x1,x2);
}
我高数学的不好，当b*b-4*a*c<0时的解我不会求~~~~只能让重输..

#include <stdio.h>
#include <math.h>
void main ()
{
double sqrt(double x);
int a,b,c;
double x1,x2,x,e,d,g,f;
scanf("%d %d %d",&a,&b,&c);
d=b*b-4*a*c;
if (a==0)
{ if (b!=0)
{x=-(double)c/(double)b;
if (x==0)
{x=-x;
printf("x=%.6lf\n",x);}
else
printf("x=%.6lf\n",x);
}
else
printf("Input error!\n");}
else if (d<0)
{d=-d;
e=