#include<stdio.h>
#include<math.h>
void main()
{
    float a,b,c,disc,x1,x2,realpart,imagpart;
    printf("请输入a,b,c的值：\n");
    scanf("%f,%f,%f",&a,&b,&c);
    printf("The equation ");
    if(fabs(a)<=1e-6)   //相当于=0
        printf("is not a quadratic\n");
    else
    {
        disc=b*b-4*a*c;
        if(fabs(disc)<=1e-6)   //相当于=0
            printf("has two equal roots:%8.4fand %8.4f\n",-b/(2*a));
        else
            if(disc>1e-6)
            {
                x1=(-b+sqrt(disc))/(2*a);
                x2=(-b-sqrt(disc))/(2*a);
                printf("has distinct real roots:%8.4f and %8.4f\n",x1,x2);
            }
            else
            {
                realpart=-b/(2*a);
                imagpart=sqrt(disc)/(2*a);
                printf("此方程有2个复解：\n");
                printf("%8.4f+%8.4fi\n",realpart,imagpart);
                printf("%8.4f-%8.4fi\n",realpart,imagpart);
            }
    }

}
出现了警告D:\vc\vc\MSDev98\MyProjects\t1\t1.1.c(20) : warning C4244: '=' : conversion from 'double ' to 'float ', possible loss of data
D:\vc\vc\MSDev98\MyProjects\t1\t1.1.c(21) : warning C4244: '=' : conversion from 'double ' to 'float ', possible loss of data
D:\vc\vc\MSDev98\MyProjects\t1\t1.1.c(27) : warning C4244: '=' : conversion from 'double ' to 'float ', possible loss of data
   而且运行结果出错，为什么呢