新手提问，将数据写入文件没效果

#include<fstream>
using namespace std;
int main()
{
    double income=123.45,expenses=987365;
    int week=7,year=2013;
    ofstream outfile("D\\a.txt",ios::out);
    outfile<<"income="<<income<<"expenses="<<expenses<<endl;
    outfile<<"week="<<week<<"year="<<year<<endl;
    outfile.close();
}[local]1[/local]