mask_array.cpp

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#include <iostream>    // for cout, endl
#include <valarray.h>  // Includes valarray and provides stream inserter.
#include <examples.h>  // Generic header for all examples.
 
typedef std::valarray<int>    valarray_t;
typedef std::valarray<bool>   maskarray_t;
 
int main(void) {
 
  // Create a valarray of ints.
  valarray_t::value_type   ibuf[10] = {0,1,2,3,4,5,6,7,8,9};
  valarray_t               vi(ibuf, 10);
 
  // Create a valarray of bools for a mask.
  maskarray_t::value_type  mbuf[10] = {1,0,1,1,1,0,0,1,1,0};
  maskarray_t              mask(mbuf,10);
 
  // Print out the valarray<int>.
  std::cout << "original valarray<int> vi\n\n" << vi << "\n\n";
 
  // Print out the valarray<bool>.
  std::cout << "original valarray<bool> mask\n\n" << mask << "\n\n";
 
  // Print a mask array.
  std::cout << "vi[mask]\n\n" << vi[mask] << "\n\n";
 
  // Double the values of the masked array and print out.
  vi[mask] += static_cast<valarray_t> (vi[mask]);
  std::cout << "vi[mask] += vi[mask]\n\n" << vi << std::endl;
 
  return 0;
}