Man Page slice.3

                       Standard C++ Library
             Copyright 1998, Rogue Wave Software, Inc.

NAME

     slice

      - A numeric array class for representing a BLAS-like  slice
     from an array.

SYNOPSIS

     #include <valarray>
     class slice ;

DESCRIPTION

     slice 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 elements in the origi-
     nal  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  opera-
     tor  (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  dis-
     tinct 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;

     };

CONSTRUCTORS

     slice();


        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