std::vector

**shuo** · 01-27-2008

Can I overload operators +/-* for std::vector? Also how can I pass it into functions?

Code:

#include <iostream>
#include <iomanip>
#include <stdio.h>      // standard input/output
#include <vector>       // stl vector header

using namespace std;    // saves us typing std:: before vector

int i;
int Particles = 5;

vector<double> addition(vector<double> X, vector<double> Y){

 int Size = (int)X.size();
 vector<double> Z;

  for(i = 0; i < Size; i++){

    Z.push_back( X[i] + Y[i]);

      }

  return  Z;
}

int main()
{

  // create an array of particle_field object pointers

  double y;
  vector<double> x_p, y_p, u_p, v_p, T_p;

  // dynamically add some elements (use new operator)

  for(i = 0; i < Particles; i++){

  x_p.push_back(0);
  y = 0.3/(Particles - 1)*i;
  y_p.push_back(y);
  u_p.push_back(0.6);
  v_p.push_back(0);

  }

T_p = 3*v_p + x_p;

T_p = addition(x_p, u_p);

}

Shuo

**laserlight** · 01-27-2008

Can I overload operators +/-* for std::vector?

Yes, but there is probably no point, especially when it not clear what adding two containers really means. Just use std::transform from <algorithm> with the appropriate function object.

**Elysia** · 01-27-2008

I think it could do you a little good to brush up on your indentation skills:
http://cpwiki.sf.net/User:Elysia/Indentation

**shuo** · 01-27-2008

Thanks for the advice

**CornedBee** · 01-28-2008

You can, but you're not allowed to, unless you involve one of your own classes in the overload.

**laserlight** · 01-28-2008

You can, but you're not allowed to, unless you involve one of your own classes in the overload.

I had the impression that since it is illegal to add to the std namespace except to specialise class templates, one could overload an operator involving only class types from the standard library as long as the operator is not in the std namespace. Where does the C++ Standard prohibit operator overloads that only involve class types from the standard library?

**CornedBee** · 01-28-2008

Huh, seems I confused that one with template specializations.

**Daved** · 01-28-2008

If you're using vector to implement some other concept or object, then you can make a class and use a vector as the implementation, then overload the operators for that class if it is appropriate. This has the added benefit of allowing you to change the container you use if you find a better way of implementing the interface.

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