#include <iostream>
#include <fstream>
using namespace std;

class File {
private:
    ifstream data_file;
public:
    File(const char *filename) {
        data_file.open(filename);
        if (!data_file.is_open()) {
            throw ("file open failed");
        }
    }

    ~File() {
        data_file.close();
        //delete[] a;
    }
};

int main() {
    File file("wrong_filename");
    return 0;
}