Array of Ofstream in c++

问题

I want 41 output files to use in my project to write text on them. first create a string array list to name those output files then I tried to define an array of ofstream objects and use list to name them, but I get this error that 'outfile' cannot be used as a function. Below is my code:

#include <sstream>
#include <string>
#include <iostream>
#include <fstream>
using namespace std ;
int main ()
{
  string list [41];
  int i=1;
  ofstream *outFile = new ofstream [41];

  for (i=1;i<=41 ;i++)
  {
    stringstream sstm;
    sstm << "subnode" << i;
    list[i] = sstm.str();
  }

  for (i=0;i<=41;i++)
    outFile[i] (list[i].c_str());

  i=1;
  for (i=1;i<=41;i++)
    cout << list[i] << endl;

  return 0; 
}

回答1:

See below for the following fixes:

don't use new unless you have to (you were leaking all files and not properly destructing them will lead to lost data; ofstreams might not be flushed if you don't close them properly, and the pending output buffer will be lost)
Use proper array indexing (starting from 0!)
Call .open(...) on a default-constructed ofstream to open a file
Recommendations:
- I'd recommend against using namespace std; (not changed below)
- I recommend reusing the stringstream. This is is good practice
- Prefer to use C++-style loop index variables (for (int i = ....). This prevents surprises from i having excess scope.
- In fact, get with the times and use ranged for

#include <sstream>
#include <string>
#include <iostream>
#include <fstream>
using namespace std;
int main ()
{
    ofstream outFile[41];

    stringstream sstm;
    for (int i=0;i<41 ;i++)
    {
        sstm.str("");
        sstm << "subnode" << i;
        outFile[i].open(sstm.str());
    }

    for (auto& o:outFile)
        cout << std::boolalpha << o.good() << endl;
}

回答2:

You can not call the constructor as you do. Try calling outFile[i].open(list[i].c_str()). Note the 'open'.

来源：https://stackoverflow.com/questions/12835406/array-of-ofstream-in-c

标签

c++

arrays

ofstream