C++数组读写txt

#include <fstream>
int main() {
    double data[10];
    ifstream in;
    in.open("data.txt");
    for (int i=0; i<10; ++i)
    {
        in>>data[i];
        cout << data[i]<<endl;
    }
    in.close();
    ofstream out;
    out.open("out.txt");
    for (i=0; i<10; ++i)
    {
        out<<data[i]<<endl;
    }
    out.close();
    return 0;
}