输入参数a,b,c,求二次方程a*x^2+b*x+c=0的根。
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
void main()
{
    float a,b,c,d;
  printf("输入一元二次方程a= , b= , c= \n");
  scanf("a=%f, b=%f, c=%f",&a,&b,&c);
  d=b*b-4*a*c;
  if(a==0)
    {
      if(b==0)
        {
          if(c==0)
              {
                    printf("0=0参数对方程无意义!");
                }
          else
              {
                    printf("C!=0方程不成立");
              }
        }
      else
      {
            printf("x=%f\n",-c/b);
        }
  }
  else
  if(d>=0)
    {
      printf("x1=%f\n",(-b+sqrt(d))/(2*a));
      printf("x2=%f\n",(-b-sqrt(d))/(2*a));
  }
  else
    {
      printf("x1=%f+%f\n",-b/(2*a),sqrt(-d)/(2*a));
      printf("x2=%f-%f\n",-b/(2*a),sqrt(-d)/(2*a));
  }
    return 0;
}

void main就不要 return 0；了  或  int main