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| <TITLE>slice_array</TITLE> |
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| <H2>slice_array</H2> |
| <P><B>Library:</B> <A HREF="2-10.html">Numerics</A></P> |
| |
| <PRE><HR><B><I>Does not inherit</I></B><HR></PRE> |
| |
| <UL> |
| <LI><A HREF="#sec1">Local Index</A></LI> |
| <LI><A HREF="#sec2">Summary</A></LI> |
| <LI><A HREF="#sec3">Synopsis</A></LI> |
| <LI><A HREF="#sec4">Description</A></LI> |
| <LI><A HREF="#sec5">Interface</A></LI> |
| <LI><A HREF="#sec6">Constructors</A></LI> |
| <LI><A HREF="#sec7">Assignment Operators</A></LI> |
| <LI><A HREF="#sec8">Computed Assignment Operators</A></LI> |
| <LI><A HREF="#sec9">Example</A></LI> |
| <LI><A HREF="#sec10">See Also</A></LI> |
| <LI><A HREF="#sec11">Standards Conformance</A></LI> |
| </UL> |
| <A NAME="sec1"><H3>Local Index</H3></A> |
| <H4>Members</H4> |
| <UL><TABLE CELLPADDING=3> |
| <TR><TD VALIGN=top> |
| <A HREF="#idx1180">operator%=()</A><BR> |
| <A HREF="#idx1180">operator&=()</A><BR> |
| <A HREF="#idx1180">operator>>=()</A><BR> |
| </TD> |
| <TD VALIGN=top><A HREF="#idx1180">operator<<=()</A><BR> |
| <A HREF="#idx1180">operator*=()</A><BR> |
| <A HREF="#idx1180">operator+=()</A><BR> |
| </TD> |
| <TD VALIGN=top><A HREF="#idx1180">operator-=()</A><BR> |
| <A HREF="#idx1180">operator/=()</A><BR> |
| <A HREF="#idx1177">operator=()</A><BR> |
| </TD> |
| <TD VALIGN=top><A HREF="#idx1180">operator^=()</A><BR> |
| <A HREF="#idx1180">operator|=()</A><BR> |
| <A HREF="#idx1176">slice_array()</A><BR> |
| </TD></TR> |
| </TABLE></UL> |
| |
| <A NAME="sec2"><H3>Summary</H3></A> |
| <P>A numeric array class for representing a BLAS-like slice from a <B><I><A HREF="valarray.html">valarray</A></I></B></P> |
| <A NAME="sec3"><H3>Synopsis</H3></A> |
| |
| <PRE>#include <valarray> |
| |
| namespace std { |
| template <class T> |
| class slice_array; |
| } |
| </PRE> |
| <A NAME="sec4"><H3>Description</H3></A> |
| <P>The <B><I><A HREF="valarray.html">valarray</A></I></B> helper class <B><I>slice_array</I></B> gives a slice view into a <B><I>valarray</I></B>. A <B><I>slice_array</I></B> is only produced by applying the slice subscript operator to a <B><I>valarray</I></B>. The elements in a <B><I>slice_array</I></B> are references to selected elements in the <B><I>valarray</I></B> (so changing an element in the <B><I>slice_array</I></B> really changes the corresponding element in the <B><I>valarray</I></B>). A <B><I>slice_array</I></B> does not itself hold any distinct elements. The template cannot be instantiated directly since all its constructors are private. However, you can easily copy a <B><I>slice_array</I></B> to a <B><I>valarray</I></B> using either the <B><I>valarray</I></B> copy constructor or the assignment operator. Reference semantics are lost at that point. </P> |
| <A NAME="sec5"><H3>Interface</H3></A> |
| |
| <UL><PRE>namespace std { |
| |
| template <class T> class slice_array { |
| public: |
| |
| // types |
| typedef T value_type; |
| |
| // destructor |
| ~slice_array(); |
| |
| // public assignment |
| void operator=(const valarray<T>& array) const; |
| |
| // computed assignment |
| void operator*=(const valarray<T>& array) const; |
| void operator/=(const valarray<T>& array) const; |
| void operator%=(const valarray<T>& array) const; |
| void operator+=(const valarray<T>& array) const; |
| void operator-=(const valarray<T>& array) const; |
| void operator^=(const valarray<T>& array) const; |
| void operator&=(const valarray<T>& array) const; |
| void operator|=(const valarray<T>& array) const; |
| void operator<<=(const valarray<T>& array) const; |
| void operator>>=(const valarray<T>& array) const; |
| |
| // other |
| void operator=(const T&); |
| |
| private: |
| // constructors |
| slice_array(); |
| slice_array(const slice_array<T>&); |
| // operator= |
| slice_array<T>& operator=(const slice_array<T>& array); |
| }; |
| } |
| </PRE></UL> |
| <A NAME="sec6"><H3>Constructors</H3></A> |
| |
| <A NAME="idx1176"></A><PRE><B>slice_array</B>(); |
| <B>slice_array</B>(const slice_array&);</PRE> |
| <UL> |
| <P>All <B><I>slice_array</I></B> constructors are private and cannot be called directly. This prevents copy construction of <B><I>slice_array</I></B>s.</P> |
| </UL> |
| |
| <A NAME="sec7"><H3>Assignment Operators</H3></A> |
| |
| <A NAME="idx1177"></A><PRE>void <B>operator=</B>(const valarray<T>& x) const;</PRE> |
| <UL> |
| <P>Assigns values from <SAMP>x </SAMP>to the selected elements of the <B><I><A HREF="valarray.html">valarray</A></I></B> that self refers to. Remember that a <B><I>slice_array</I></B> never holds any elements itself, it simply refers to selected elements in the <B><I>valarray</I></B> used to generate it.</P> |
| </UL> |
| |
| |
| <A NAME="idx1178"></A><PRE>slice_array<T>& |
| <B>operator=</B>(const slice-_array<T>& x);</PRE> |
| <UL> |
| <P>Private assignment operator. Cannot be called directly, thus preventing assignment between <B><I>slice_array</I></B>s.</P> |
| </UL> |
| |
| |
| <A NAME="idx1179"></A><PRE>void <B>operator=</B>(const T& x);</PRE> |
| <UL> |
| <P>Assigns <SAMP>x</SAMP> to the selected elements of the <B><I><A HREF="valarray.html">valarray</A></I></B> that self refers to. </P> |
| </UL> |
| |
| <A NAME="sec8"><H3>Computed Assignment Operators</H3></A> |
| |
| <A NAME="idx1180"></A><PRE>void <B>operator*=</B>(const valarray<T>& val) const; |
| void <B>operator/=</B>(const valarray<T>& val) const; |
| void <B>operator%=</B>(const valarray<T>& val) const; |
| void <B>operator+=</B>(const valarray<T>& val) const; |
| void <B>operator-=</B>(const valarray<T>& val) const; |
| void <B>operator^=</B>(const valarray<T>& val) const; |
| void <B>operator&=</B>(const valarray<T>& val) const; |
| void <B>operator|=</B>(const valarray<T>& val) const; |
| void <B>operator<<=</B>(const valarray<T>& val) const; |
| void <B>operator>>=</B>(const valarray<T>& val) const;</PRE> |
| <UL> |
| <P>Applies the indicated operation using elements from <SAMP>val</SAMP> to the selected elements of the <B><I><A HREF="valarray.html">valarray</A></I></B> that self refers to. Remember that a <B><I>slice_array</I></B> never holds any elements itself; it simply refers to selected elements in the <B><I>valarray</I></B> used to generate it.</P> |
| </UL> |
| |
| <A NAME="sec9"><H3>Example</H3></A> |
| |
| <UL><PRE>// |
| // slice_array.cpp |
| // |
| |
| #include <valarray.h> // Includes valarray and provides stream inserter. |
| |
| typedef std::valarray<int> valarray_t; |
| |
| int main(void) { |
| |
| valarray_t::value_type ibuf[9] = {0,1,2,3,4,5,6,7,8}; |
| |
| // Create a valarray initialized to the sequence of |
| // integers above. |
| valarray_t vi (ibuf,9); |
| |
| std::cout << "original valarray vi\n\n" << vi << "\n\n"; |
| |
| // Display a slice of the valarray. |
| std::cout << "vi[slice(0,3,3)]\n\n" |
| << vi[std::slice(0,3,3)] << "\n\n"; |
| |
| // Unfortunately, slice_arrays were not designed to be |
| // easily combined. An explicit conversion to valarray |
| // is required, leaving us with this awkward casting |
| // syntax. |
| vi[std::slice (0,3,3)] = |
| static_cast<valarray_t>(vi[std::slice (1,3,3)]) + |
| static_cast<valarray_t>(vi[std::slice (2,3,3)]); |
| |
| // The operation above uses slices ([0-2],3,3) to treat |
| // our valarray as a 3-dimensional array: |
| // |
| // 0 1 2 3 = 1 + 2 |
| // 3 4 5 9 = 4 + 5 |
| // 6 7 8 15 = 7 + 8 |
| // | | | | | | |
| // | | +-slice(2,3,3) | | +- slice_array for |
| // | | | | arithmetic operand. |
| // | +---slice(1,3,3) | +----- slice_array for |
| // | | arithmetic operand. |
| // +-----slice(0,3,3) +---slice_array assignment |
| // refers to valarray. |
| |
| std::cout << "vi[slice(0,3,3)] = vi[slice(1,3,3)] + " |
| << "vi[slice(2,3,3)]\n\n" |
| << vi << std::endl; |
| |
| return 0; |
| } |
| |
| |
| Program Output: |
| </PRE></UL> |
| <UL><PRE>original valarray vi |
| |
| [0,1,2,3,4,5,6,7,8] |
| |
| vi[slice(0,3,3)] |
| |
| [0,3,6] |
| |
| vi[slice(0,3,3)] = vi[slice(1,3,3)] + vi[slice(2,3,3)] |
| |
| [3,1,2,9,4,5,15,7,8] |
| </PRE></UL> |
| <A NAME="sec10"><H3>See Also</H3></A> |
| <P><B><I><A HREF="slice.html">slice</A></I></B>, <B><I><A HREF="valarray.html">valarray</A></I></B>, <B><I><A HREF="gslice.html">gslice</A></I></B>, <B><I><A HREF="gslice-array.html">gslice_array</A></I></B>, <B><I><A HREF="mask-array.html">mask_array</A></I></B>, <B><I><A HREF="indirect-array.html">indirect_array</A></I></B></P> |
| <A NAME="sec11"><H3>Standards Conformance</H3></A> |
| <P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 26.3.5</I></P> |
| |
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