为啥我这个代码输出为零啊

Question

#include<stdio.h>
int main()
{
double i=1,eps,a=1,b;
double c=1,s=0,x=1;
scanf("%1e",&eps);
while(b>=eps)
{
b=c/x;
c=ca;
i+=2;
x=xi;
s=b+s;
a++;
}
printf("PI = %.7lf\n",2*s);
return 0;
}

Answer 1

b应该给他一个初始值