arrayexample.cc

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#define ARRAYEXAMPLE_VERSION \
  "ARRAYEXAMPLE   V1.1   Demonstrate array usage"

// include iostream for output to terminal
#include <iostream>
// provide function sqrt()
#include <cmath>

// provide aff::Array class template
#include <aff/array.h>
// provide aff::Shaper class template
#include <aff/shaper.h>
// provide function template aff::subarray
#include <aff/subarray.h>
// provide function template to produce a dump of array contents
#include <aff/dump.h>

using std::cout;
using std::endl;

/* ---------------------------------------------------------------------- */

void section(const char* s, const char l='-')
{
  cout << endl << s << endl;
  const char* p=s;
  while (*p) { cout << l; ++p; }
  cout << endl;
}

/* ---------------------------------------------------------------------- */

template<class T>
  std::ostream& operator<<(std::ostream& os, const aff::ConstArray<T>& a)
{
  // size of array dimensions
  int N=a.size(0);
  int M=a.size(1);

  // report size of array
  cout << "Elements (i,j) of " << N << "x" << M << " array:" << endl;

  // width of first column, where value of i will be printed
  const int firstwidth=6;
  // width of columns:
  int columnwidth=(78-firstwidth)/M;

  // print column headings
  cout.width(firstwidth);
  cout.setf(std::ios_base::left, std::ios_base::adjustfield);
  cout << "";
  for (int j=a.first(1); j<=a.last(1); j++)
  {
    cout << "j=";
    cout.width(columnwidth-2);
    cout.setf(std::ios_base::left, std::ios_base::adjustfield);
    cout << j;
  }
  cout << endl;

  // print contents of array
  // outer loop: first index
  for (int i=a.first(0); i<=a.last(0); i++)
  {
    cout << "i=";
    cout.width(firstwidth-2);
    cout.setf(std::ios_base::left, std::ios_base::adjustfield);
    cout << i;
    // inner loop: second index
    for (int j=a.first(1); j<=a.last(1); j++)
    {
      cout.width(columnwidth);
      cout << a(i,j);
    }
    cout << endl;
  }
  return os;
} // std::ostream& operator<<(std::ostream& os, const aff::ConstArray<T>& a)

/*======================================================================*/

int main()
{
  cout << ARRAYEXAMPLE_VERSION << endl;

  // create a 3x4 array of type float
  aff::Array<float> A(3,4);

  // print array (layout and contents) to terminal
  section("Array A after being created:");
  cout << A;

  // set all elements in array to 5.2
  A=5.2;
  section("Array A after all elements being set to 5.2:");
  cout << A;

  /* ---------------------------------------------------------------------- */

  section("Demonstrate effect of shallow copy", '=');
  // create a second array
  aff::Array<float> B;

  // let B be a copy of A
  B=A;

  // B just references the same memory; thus changing values in A and B will
  // effectively change the same array values
  A(2,3)=10.7;
  B(3,1)=-19.3;

  // both modifications are present in A
  section("Array A after assignment to B and to A:");
  cout << A;

  /* ---------------------------------------------------------------------- */

  section("Demonstrate effect of deep copy", '=');
  // create a copy by actually copying all elements
  B=A.copyout();

  // modify B
  B(3,3)=102.3;
  section("Array B after assignment to B:");
  cout << B;
  section("Array A after assignment to B:");
  cout << A;

  /* ---------------------------------------------------------------------- */

  section("Demonstrate array usage with custom index range", '=');

  /* To create an array which does not use index range beginning with 1, use
   * the function Shaper, which is available through aff/shaper.h
   */
  A=aff::Array<float>(aff::Shaper(-2,6)(12,16));
  A=sqrt(2.);
  section("Array A after being assigned to array of different shape:");
  cout << A;
}

/* ----- END OF arrayexample.cc ----- */