C++ Valarray Library - gslice Function


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Description

A valarray generalized slice is specified by a starting index, a set of sizes, and a set of strides and this class represents a valarray generalized slice selector (a multidimensional slice). It does not contain nor refers to any element - it only describes a selection of elements to be used as an index in valarray::operator[].

Declaration

Following is the declaration for std::gslice function.

class gslice;

C++11

class gslice;

Parameters

none

Return Value

none

Exceptions

Basic guarantee − if any operation performed on the elements throws an exception.

Data races

All elements effectively copied are accessed.

Example

In below example explains about std::gslice function.

#include <iostream>
#include <cstddef>
#include <valarray>

int main () {
   std::valarray<int> foo (12);
   for (int i=0; i<12; ++i) foo[i]=i;

   std::size_t start=1;
   std::size_t lengths[]= {2,3};
   std::size_t strides[]= {7,2};

   std::gslice mygslice (start,
      std::valarray<std::size_t>(lengths,2),
      std::valarray<std::size_t>(strides,2));

   std::valarray<int> bar = foo[mygslice];

   std::cout << "gslice:";
   for (std::size_t n=0; n<bar.size(); n++)
      std::cout << ' ' << bar[n];
   std::cout << '\n';

   return 0;
}

Let us compile and run the above program, this will produce the following result −

gslice: 1 3 5 8 10 0
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