求c++大佬指点！！！

Question

 

 

 

 

Answer 1

#include<stdio.h>
#include<math.h> 
int main(){
	double x, y = 1;
	scanf("%lf", &x);
	double sum = 0, temp;
	int flag = -1;
	for(int i = 1; ; i++){
		flag *= -1;
		temp = pow(x,2*i-1);
		if(i > 1)
			y = y*(2*i-2)*(2*i-1);
		if(temp/y < 0.000001)
			break;
		sum += flag*temp/y;
	}
	printf("%0.5lf", sum);
}