Krash vid skrivning till fil (C++)

#ifndef FileIO_Included
#define FileIO_Included

#include <iostream>
#include <stdlib.h>
#include <fstream>
using namespace std;
class FileIO{
    public:
      FileIO(){}

      void readLine(char* file, char* data){
        cout << "Open file " << file << endl;
        ifstream toread(file);
        cout << "File opened\n";
            if(toread.good()){
               toread.getline(data,sizeof(data));
               cout << "Data read\n";
            }
      }
      void writefile(char* file, char* data){
        cout << "Write to file: " << file << endl;
      ofstream towhrite("Link.txt");
        cout << "File opened\n";
        towhrite << data;
            towhrite.close();
        cout << "Data written\n";
      }

};

#endif

try{
                        fileio.writefile("Link.txt",url);
                    }catch (exception& ex){
                        cerr << "exception caught: " << ex.what() << endl;
                    }