Question

I have the following template function which prints to cout:

 template <typename T> void  prn_vec(const std::vector < T >&arg, string sep='')      {         for (unsigned n = 0; n < arg.size(); n++) {              cout << arg[n] << sep;             }         return;     }       // Usage:     //prn_vec<int>(myVec,'\t');      // I tried this but it fails:     /*       template <typename T> void  prn_vec_os(const std::vector < T >&arg,        string    sep='',ofstream fn)       {         for (unsigned n = 0; n < arg.size(); n++) {              fn << arg[n] << sep;               }         return;       }    */ 

How can I modify it so that it also takes file handle as input and print out to that file as referred by the filehandle?

So that we can do something like:

#include <fstream> #include <vector> #include <iostream> int main () {    vector <int> MyVec;   MyVec.push_back(123);   MyVec.push_back(10);    ofstream myfile;   myfile.open ('example.txt');   myfile << 'Writing this to a file.\n';     // prn_vec(MyVec,myfile,'\t');    myfile.close();   return 0; } 

Answer 1

template <typename T>  ostream& prn_vec(ostream& o, const std::vector < T >&arg, string sep='')  {     for (unsigned n = 0; n < arg.size(); n++) {          o << arg[n] << sep;         }     return o; }   int main () {    vector <int> MyVec;   // ...   ofstream myfile;    // ...   prn_vec(myfile, MyVec, '\t');    myfile.close();   return 0; }