C++: Future Directions in Language Innovation

Example: Average-Neighbors

OpenMP code (example a1):

#pragma omp parallel for
for( i=1; i < n; ++i )
b[i] = (a[i] + a[i-1]) / 2.0;

Concur code:

active for each( int i in range(1,n) ) {
b[i] = (a[i] + a[i-1]) / 2.0;
}

•Works also with STL and BCL collections, not just arrays.

•Or use a parallel version of the std::transform algorithm.

ptransform( a.begin()+1, a.end(), a.begin(), b.begin(), (_1+_2) / 2.0 );

first input range

second
input
range

output

range

how to compute

the output


	note: taking explicit advantage of knowing how iterators traverse collections, and which ones are read vs. written

	template< class In, class Out, class Op >
	OutputIterator pitransform( In first, In last, Out result, Op op) {
	for( ; first < last; ++first, ++out ) active {
	*out = op(first);
	}
	}