🚀 go-pugleaf

In article <Ahxi6.6779$mO6.136359@news6-win.server.ntlworld.com>,
richardcrane <richardcrane@ntlworld.com> wrote:
>can somebody help me iam a beginner in C++.  I want to pass an array between
>3 different functions that are a user definable size.

I take it you mean the array size is defined by the user when the program 
runs?  Maybe this will give you the idea:

  #include <iostream>

  using namespace std; // quick and dirty namespace hack

  void ReadData (double d[], int size)
  {
      for (int k = 0; k < size; ++k)
      {
          cout << "Enter d[" << k << "]: ";
          cin >> d[k];
      }
  }

  void DisplayData (double d[], int size)
  {
      for (int k = 0; k < size; ++k)
      {
          cout << "d[" << k << "] = " << d[k] << endl;
      }
  }

  int main ()
  {
    cout << "How many data items? ";
    int howmany;
    cin >> howmany;
    double *data = new double[howmany]; // allocate the array dynamically
    ReadData (data, howmany);  // must pass the size, too
    DisplayData (data, howmany);
    delete [] data;  // clean up after yourself when done
    return 0;
  }


This is easier using vectors instead of arrays:


  #include <iostream>
  #include <vector>

  using namespace std; // quick and dirty namespace hack

  void ReadData (vector<double>& d)
  {
      cout << "Enter data items one by one, hit ^D when finished...\n";
      double x;
      while (cin >> x)
      {
          d.push_back(x);  // vector automatically expands as needed
             // and keeps track of how much data it contains
      }
  }

  void DisplayData (vector<double>& d)
  {
      for (int k = 0; k < d.size(); ++k)
      {
          cout << "d[" << k << "] = " << d[k] << endl;
      }
  }

  int main ()
  {
    // no need to ask for how much data
    // declare vector as zero-length initially
    vector<double> data;
    ReadData (data);  // vector keeps track of its own size
    DisplayData (data);
    // vectors clean up after themselves for you
    return 0;
  }

-- 
Jon Bell <jtbell@presby.edu>                        Presbyterian College
Dept. of Physics and Computer Science        Clinton, South Carolina USA