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How to assign a multiple entries in array using [ ] and = operators

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Started by Misery July 05, 2012 09:54 AM

1 comment, last by Matt-D 11 years, 9 months ago

Misery

354

Author

July 05, 2012 09:54 AM

Hi there,

I have a following problem: I would like to make an array template in C++ that would have similar operator like one in Scilab/Matlab:



   Array[range] = scalar;

This expression would cause all elements of Array listed in range, take value of scalar. How do I do that?





class FloatArray

{

  public:

   float Elements[100];



  //how do I define operator

  ???  operator [  ] (int *Range)

  { }



  //and operator

  ????  operator = (???)

  { }

};

To obtain this?

Regards,
Misery

Hodgman

52,717

July 05, 2012 10:10 AM

Something along the lines of this code (untested), which returns a proxy object to perform the assignment should work:

struct Range

{

  int begin, end;

};



class FloatRangeProxy

{

  float* begin;

  float* end;

public:

  FloatRangeProxy( float* b, float* e ) : begin(b), end(e) {}



  const float operator=( float f )

  {

    for( float* i=begin; i!=end; ++i )

      *i = f;

    return f;

  }

};



class FloatArray

{

  float Elements[100];

public:

  FloatRangeProxy  operator [] (const Range& r)

  {

    return FloatRangeProxy( Elements + r.begin, Elements + r.end );

  }

};

. 22 Racing Series .

Matt-D

1,574

July 08, 2012 09:29 PM

As an inspiration, you can also look at open-source NT2 @ http://github.com/MetaScale/nt2/ which has a placeholder operator, nt2::_.
Example usage:
[source lang="cpp"]using nt2::_;

nt2::table<T> a0, a1, b0, b1, a, b, c;

a1 = nt2::sum(a0(_));
b1(_,_,1) = 0.5*b0(_,_,1);
c = nt2::horzcat(a(_), b(_));

c = b(3, _);
b(3, _) = b(2, _);
b(2, _) = c;
[/source]

How to assign a multiple entries in array using [ ] and = operators

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How to assign a multiple entries in array using [ ] and = operators

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