C++头文件及所包含的函数

#include <iostream>
#include <iomanip>
using namespace std;
int main ()
{
    cout<<"10.0/6.0="<<10.0/6<<"无fixed"<<endl;
    cout<<"10.0/6.0="<<10.0/6<<fixed<<setprecision(8)<<"有fixed"<<endl;
    cout<<"10.0/6.0="<<10.0/6<<"无fixed"<<endl;
    cout<<"100.0/6.0="<<100000000.0/6<<fixed<<setprecision(3)<<"有fixed"<<endl;　　//此处格式函数无效，输出仍为8位小数
    return 0;
}