习题：输入abc的值求一元二次方程的解

# include <stdio.h>
# include <math.h>

int main(void)
{
int a, b, c;
float x1,x2;

begin:
printf("请输入一元二次方程ax^2+bx+c=0中abc的值：\n");
printf("a = ");scanf("%d",&a);
printf("b = ");scanf("%d",&b);
printf("c = ");scanf("%d",&c);

float jesse = b*b - 4*a*c; //该行之前写在上面的printf语句上，导致a b c没有进行赋值计算，程序结果出错。

if (jesse>0)
{
x1 = 2*c/(-b+sqrt(jesse));
x2 = 2*c/(-b-sqrt(jesse));
printf("该方程有两个解：\nx1 = %f, x2 = %f\n",x1, x2);
}

else if (jesse==0)
{
x1 = -b/(2*a);
x2 = x1;
printf("该方程有一个解：x1 = x2 = %f\n",x1);
}

else
printf("该方程无解！\n");
goto begin;

return 0;
}