Question

I’m trying to create output files subscripted by a dynamic index ( d = {0,…,NUM_DEMES-1}). Currently, I’m only getting output files for the first value (d=0).

#include <sstream>
#include <string>

void Simulation::updateSimulation( double t )
{
 ...
 ofstream abundanceStream;
 ofstream abHeaderStream;     

 if ( step == 1 ) {
   for ( int d = 0; d < NUM_DEMES; d++ ) {
    abundanceStream.open( makeFilename( "Abundances_", d ).c_str(),ios::out);
    abHeaderStream.open( makeFilename( "Abundances_IDs_", d ).c_str(),ios::out);
   }
 }

 for ( int d = 0; d < NUM_DEMES; d++ ) {
   abundanceStream.open( makeFilename( "Abundances_", d ).c_str(),ios::app); 
   abHeaderStream.open( makeFilename( "Abundances_IDs_", d ).c_str(),ios::app);
 }
}

string Simulation::makeFilename( const string& basename, int index )
{
  ostringstream result;
  result << basename << index;
  return result.str();
}

This creates Abundances_0 and Abundances_IDs_0 but nothing else. I can write to those files. I can create the other filenames just fine, but the files just don’t appear.

I’m probably missing something basic about streams, but I haven’t been able to figure out what.

EDIT

The following code prints to screen the right filenames:

  for ( int d = 0; d < NUM_DEMES; d++ ) {
    abundanceStream.open( makeFilename( "Abundances_", d ).c_str(),ios::app);
    abundanceStream << "stuff\n";
    cout << makeFilename( "Abundances_", d ).c_str() << endl;
    abHeaderStream.open( makeFilename( "Abundances_IDs_", d ).c_str(),ios::app);
    abHeaderStream << "more stuff\n";
    cout << makeFilename( "Abundances_IDs_", d ).c_str() << endl;
  }

But “stuff” and “more stuff” only appear in the Abundances_0 and Abundances_IDs_0.

Answer 1

You are always using the same objects. You can either close the streams after “use” or use different objects for each file.