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CppBoostArray

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(C++) boost::array

An array class from the Boost C++ library.

It is safer to use then a plain array, because it is not a pointer in disguise.

The use of a std::vector is recommened by default, but if you need not to use resizing, a boost::array might be faster: it does not need to be ready for a resizing operations, which saves overhead.

For doing mathematical operations on a sequence of values, you could also use a std::valarray.

Unlike a plain array, a boost::array can do range checking:

include <boost/array.hpp>

int main()
{
  const int size = 10;
  boost::array<double,size> myArray;
  for (int i=0; i!=size+1; ++i) myArray.at(i)=i; //Checks range
  for (int i=0; i!=size+1; ++i) myArray[i]=i; //Does not check range
  return 0;
}

More advanced example using for-loops:

include <iostream>

include <algorithm>

include <boost/array.hpp>


int main()
{
  const int size = 10;
  boost::array<double,size> myArray;
  for (int i=0; i!=size; ++i) myArray[i]=i;
  for (int i=0; i!=size; ++i) std::cout << myArray[i] << std::endl;
  for (int i=0; i!=size; ++i) myArray[i]*=myArray[i];
  for (int i=0; i!=size; ++i) std::cout << myArray[i] << std::endl;
}

Example using std::for_each:

include <iostream>

include <algorithm>

include <boost/array.hpp>


class Init
{
  public:
  Init() : i(0) {}
  template <class T> void operator()(T& j) { j = i; i++; }
  private:
  int i;
};
class Couter
{
  public:
  Couter() {}
  void operator()(double& t) { std::cout << t << std::endl; }
  template <class T> void operator()(const T& t) { std::cout << t <<  std::endl; }
};
class Squarer
{
  public:
  Squarer() {}
  template <class T> void operator()(T& t) { t*=t; }
};
int main()
{
  boost::array<double,10> myArray;
  std::for_each(myArray.begin(),myArray.end(),Init());
  std::for_each(myArray.begin(),myArray.end(),Couter());
  std::for_each(myArray.begin(),myArray.end(),Squarer());
  std::for_each(myArray.begin(),myArray.end(),Couter());
}

Array links

• C++ concept
• C#

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