关于#C++#的问题，如何解决？

C++语言实现sin(x)，计算结果会出现大于1的情况。希望有各位帮忙解答

#include

#include
using namespace std;

int main()
{
double f(double x);
double s, k;
cout<<"Please enter an mumber: s = ";
cin>>s;
cout<<endl;
k = f(s);
cout<<"The result is "<<k<<endl;
return 0;
}

//求解幂函数
double power(double m, int n)
{
double p = 1.0;
for(int i = 1; i <= n; i ++)
p *= m;
return p;
}

//求解阶乘
int factorial(int g)
{
int a = 1, i;
if (g == 0)
a = 1;
if (g > 0)
for(i = 1; i <= g; i++)
a *= i;
return a;
}

double f(double x)
{
int factorial(int g);
double power(double m, int n);
double y = 0.0;
int i = 1;
do
{
y = (i % 4 == 1) ? y + (power(x, i)/factorial(i)) : y - (power(x, i)/factorial(i));
i += 2;
}while((power(x, i) / factorial(i)) >= 1e-10);
return y;
}

Please enter an mumber: s = 4

The result is -1.26779
Press any key to continue

我的解答思路和尝试过的方法

我想要达到的结果

修改处见注释，供参考：

#include <iostream>
using namespace std;
int main()
{
    double f(double x);
    double s, k;
    cout << "Please enter an mumber: s = ";
    cin >> s;
    cout << endl;
    k = f(s);
    cout << "The result is " << k << endl;
    return 0;
}
//求解幂函数
double power(double m, int n)
{
    double p = 1.0;
    for (int i = 1; i <= n; i++)
        p *= m;
    return p;
}
//求解阶乘
double  factorial(int g)  // 修改
{
    int i;
    double a = 1;      // 修改
    if (g == 0)
        a = 1;
    if (g > 0)
        for (i = 1; i <= g; i++)
            a *= i;
    return a;      // 修改
}
double f(double x)
{
    double factorial(int g);  // 修改
    double power(double m, int n);
    double y = 0.0;
    int i = 1, sign = 1;    // 修改
    while ((power(x, i) / factorial(i)) >= 1e-10) {   // 修改
        y = (sign > 0) ? y + (power(x, i) / factorial(i)) : y - (power(x, i) / factorial(i));
        i += 2;
        sign = -sign; // 修改
    }
    return y;
}