overloading an operator that has already been defined

Question

I want to overload operator * but I keep getting function "operator*(int, int)" has already been defined. I'm using Thrust library and want to use my own * in my kernel.

 __device__ int operator*(int x, int y)
{
    int value = ...                                    
    return value;                                     
}

Answer 1

What I want to do is to use Thrust's reduction with my own * operator

thrust::reduce offers you an opportunity to use your own binary operator in the reduction. The operator should be provided via a C++ functor.

Here's a worked example showing the use of a binary operator to find the maximum value in a set of numbers:

$ cat t1093.cu
#include <thrust/device_vector.h>
#include <thrust/reduce.h>
#include <iostream>

const int dsize = 10;

struct max_op
{
template <typename T>
  __host__ __device__
  T operator()(const T &lhs, const T &rhs) const
  {
    return (lhs>rhs)?lhs:rhs;
  }
};

int main(){

   thrust::device_vector<int> data(dsize, 1);
   data[2] = 10;
   int result = thrust::reduce(data.begin(), data.end(), 0, max_op());
   std::cout << "max value: " << result << std::endl;
   return 0;
}
$ nvcc -o t1093 t1093.cu
$ ./t1093
max value: 10
$