slice(3C++) - slice(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEslice
- A numeric array class for representing a BLAS-like slice from an
array.
SYNOPSIS
#include <valarray>
class slice ;
DESCRIPTIONslice allows you to represent a BLAS-like slice from an array. A BLAS
slice contains a starting index, a length, and a stride. The index
indicates the first element in the slice, the length determines the
number of elements, and the stride indicates the interval between ele‐
ments in the original array. For instance, the slice (1,3,2) applied to
the array (1,2,3,4,5,6,7) produces the array (2,4,6).
When applied to a valarray using the slice subscript operator (see
valarray) a slice produces a slice_array. The slice_array gives a view
into the original valarray that is tailored to match parameters of the
slice. The elements in a slice_array are references to the elements in
the original array. This means you need to explicitly copy the
slice_array into another valarray in order to have a distinct array.
INTERFACE
class slice {
public:
// constructors
slice();
slice(size_t, size_t, size_t);
// Accessors
size_t start() const;
size_t size() const;
size_t stride() const;
};
CONSTRUCTORSslice();
Creates a slice specifying no elements. This constructor is only intended
to allow the creation of arrays of slices.
slice(size_t start, size_t length, size_t stride);
Creates a slice with starting index, length, and stride as indicated by the
arguments.
slice(const slice&)
Creates a slice with starting index, length, and stride as indicated by the
slice argument.
ACCESSORS
size_t start();
Returns the starting index of the slice.
size_t size();
Returns the length of the slice.
size_t stride();
Returns the stride of the slice.
EXAMPLE
//
// slice.cpp
//
#include "valarray.h" // Contains a valarray stream inserter
using namespace std;
int main(void)
{
int ibuf[10] = {0,1,2,3,4,5,6,7,8,9};
// create a valarray of ints
valarray<int> vi(ibuf,10);
// print it out
cout << vi << endl;
// print out a slice
cout << valarray<int>(vi[slice(1,3,2)]) << endl;
return 0;
}
Program Output
[0,1,2,3,4,5,6,7,8,9]
[1,3,5]
WARNINGS
If your compiler does not support namespaces, then you do not need the
using declaration for std.
SEE ALSO
valarray, slice_array, gslice, gslice_array, mask_array, indirect_array
Rogue Wave Software 02 Apr 1998 slice(3C++)
