//Visual 6.0环境下
# include <iostream>
# include <fstream>
using namespace std;

int main ()
{
    ofstream outfile;
    outfile.open("f1.dat",ios::out); //为什么我把它改成("e:\c++\f1.dat",ios::out)
    if(!outfile)                                            //注：目录没有错。
        cout<<"open error !"<<endl;
    else
        cout<<"open good !"<<endl;
    outfile.close();
    return 0;

}

谢谢楼上两位了，两位的方法都很好！！