}while (‘y’== ch || ‘Y’== ch); 各位大佬，这个程序为什么会报错？

Question

一元二次方程

# include <stdio.h>

# include <math.h> 

int main(void)

{ 

double a, b, c;

double delta;

double x1, x2;

char ch;

do

{

printf("请输入一元二次方程的三个系数：\n");

printf("a =");

scanf("%lf", &a);

printf("b =");

scanf("%lf", &b);

printf("c =");

scanf("%lf", &c); 

delta = b*b - 4*a*c;

if(delta > 0)

{

x1 = (-b + sqrt(delta)) / (2*a);

x2 = (-b - sqrt(delta)) / (2*a);

printf("有两个解，x1 = %lf, x2 = %lf\n", x1, x2);

}

else if (0 == delta)

{

    x1 = x2 = (-b) / (2*a);

printf("有唯一解， x1 = x2 = %lf\n", x1, x2);

}

else

{

printf("无实数解！\n"); 

}

printf("继续请输入(y/n);"):

    scanf(" %c", &ch);                             

    

    

}while (‘y’== ch  || ‘Y’== ch);

return 0;

}