出现了显示-nan错误

Question

#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#define EPS 1e-6

int main()
{
float a,b,c,disc,p,q;
printf("Please enter a,b,c:");
scanf("%f,%f,%f",&a,&b,&c);
disc=bb-4ac;
p=-b/(2a);
q=sqrt(disc)/(2*a);
if(fabs(a)<=EPS)
{
printf("\nIt is not a quadratic equation!\n");
exit(0);
}
else if(disc<0)printf("\nTwo complex roots: x1=%.2f+%.2fi,x2=%.2f-%.2fi",p,q,p,q);
else if(disc>0)printf("\nTwo unequal real roots: x1=%.2f,x2=%.2f",p+q,p-q);
else
printf("\nTwo equal real roots: x1=x2=%.2f",p)
return 0;
}

Answer 1

if(fabs(a)<=EPS)
这个判断你要提前啊，否则如果a为0的话，前面两行已经将a作为分母在执行代码了，就出现NAN错误了啊