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| <TITLE>__distance_type()</TITLE> |
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| <H2>__distance_type()</H2><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">See Also</A></LI> |
| </UL> |
| <A NAME="sec1"><H3>Local Index</H3></A> |
| No Entries |
| <A NAME="sec2"><H3>Summary</H3></A> |
| <P>A function that determines the type of distance used by an iterator. </P> |
| <BLOCKQUOTE><HR><B> |
| NOTE -- This function is now obsolete. It is retained here to<br>support compilers that do not include partial specialization, but<br>will be dropped in a subsequent release. |
| </B><HR></BLOCKQUOTE> |
| <A NAME="sec3"><H3>Synopsis</H3></A> |
| |
| <UL><PRE>#include <iterator> |
| template <class Category, class T, class Distance, |
| class Pointer, class Reference> |
| inline Distance* |
| __distance_type(const iterator<Category, T, |
| Distance, Pointer, Reference>&); |
| template <class T> |
| inline ptrdiff_t* __distance_type(const T*); |
| </PRE></UL> |
| <A NAME="sec4"><H3>Description</H3></A> |
| <P>The <SAMP>__distance_type()</SAMP> family of function templates returns a pointer to a value that is of the same type as that used to represent a distance between two iterators. The first of these takes an iterator of a particular type and returns a pointer to a default value of the <B><I>difference_type</I></B> for that iterator. The <SAMP>T*</SAMP> form of the function returns <SAMP>ptrdiff_t*</SAMP>.</P> |
| <P>Generic algorithms use this function to create local variables of the correct type. The <SAMP>__distance_type()</SAMP> functions are typically used like this:</P> |
| |
| <UL><PRE>template <class Iterator> |
| void foo(Iterator start, Iterator finish) |
| { |
| __foo(begin,end,__distance_type(first)); |
| } |
| |
| template <class Iterator, class Distance> |
| void __foo(Iterator start, Iterator finish, Distance*> |
| { |
| Distance d = Distance(); |
| distance(start,finish,d); |
| ... |
| } |
| </PRE></UL> |
| <P>The auxiliary function template allows the algorithm to extract a distance type from the first iterator and then use that type to perform some useful work.</P> |
| <A NAME="sec5"><H3>See Also</H3></A> |
| <P>Other iterator primitives: <SAMP><A HREF="--iterator-category.html">__iterator_category()</A></SAMP>, <SAMP><A HREF="distance.html">distance()</A></SAMP>, <SAMP><A HREF="advance.html">advance()</A></SAMP></P> |
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