📄 uninitialized_fill_n.html
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<HTML><!-- -- Copyright (c) 1996-1999 -- Silicon Graphics Computer Systems, Inc. -- -- Permission to use, copy, modify, distribute and sell this software -- and its documentation for any purpose is hereby granted without fee, -- provided that the above copyright notice appears in all copies and -- that both that copyright notice and this permission notice appear -- in supporting documentation. Silicon Graphics makes no -- representations about the suitability of this software for any -- purpose. It is provided "as is" without express or implied warranty. -- -- Copyright (c) 1994 -- Hewlett-Packard Company -- -- Permission to use, copy, modify, distribute and sell this software -- and its documentation for any purpose is hereby granted without fee, -- provided that the above copyright notice appears in all copies and -- that both that copyright notice and this permission notice appear -- in supporting documentation. Hewlett-Packard Company makes no -- representations about the suitability of this software for any -- purpose. It is provided "as is" without express or implied warranty. -- --><Head><Title>uninitialized_fill_n</Title><!-- Generated by htmldoc --></HEAD><BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" ALINK="#ff0000"> <IMG SRC="CorpID.gif" ALT="SGI" HEIGHT="43" WIDTH="151"> <!--end header--><BR Clear><H1>uninitialized_fill_n</H1><Table CellPadding=0 CellSpacing=0 width=100%><TR><TD Align=left><Img src = "allocators.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD><TD Align=right><Img src = "function.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD></TR><TR><TD Align=left><Img src = "algorithms.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD><TD Align=right></TD></TR><TR><TD Align=left VAlign=top><b>Categories</b>: allocators, algorithms</TD><TD Align=right VAlign=top><b>Component type</b>: function</TD></TR></Table><h3>Prototype</h3><pre>template <class ForwardIterator, class Size, class T>ForwardIterator uninitialized_fill_n(ForwardIterator first, Size n, const T& x);</pre> <h3>Description</h3>In C++, the operator <tt>new</tt> allocates memory for an object and thencreates an object at that location by calling a constructor. Occasionally,however, it is useful to separate those two operations. <A href="#1">[1]</A> If each iteratorin the range <tt>[first, first + n)</tt> points to uninitializedmemory, then <tt>uninitialized_fill_n</tt> creates copies of <tt>x</tt>in that range. That is, for each iterator <tt>i</tt> in the range <tt>[first,first + n)</tt>, <tt>uninitialized_fill_n</tt> creates a copy of <tt>x</tt> in the location pointed to <tt>i</tt> by calling <tt><A href="construct.html">construct</A>(&*i, x)</tt>.<h3>Definition</h3>Defined in the standard header <A href="memory">memory</A>, and in the nonstandardbackward-compatibility header <A href="algo.h">algo.h</A>.<h3>Requirements on types</h3><UL><LI><tt>ForwardIterator</tt> is a model of <A href="ForwardIterator.html">Forward Iterator</A>.<LI><tt>ForwardIterator</tt> is mutable.<LI><tt>Size</tt> is an integral type that is convertible to <tt>ForwardIterator</tt>'s distance type.<LI><tt>ForwardIterator</tt>'s value type has a constructor that takes a single argument of type <tt>T</tt>.</UL><h3>Preconditions</h3><UL><LI><tt>n</tt> is nonnegative.<LI><tt>[first, first + n)</tt> is a valid range.<LI>Each iterator in <tt>[first, first + n)</tt> points to a region of uninitialized memory that is large enough to store a value of <tt>ForwardIterator</tt>'s value type.</UL><h3>Complexity</h3>Linear. Exactly <tt>n</tt> constructor calls.<h3>Example</h3><pre>class Int {public: Int(int x) : val(x) {} int get() { return val; }private: int val;}; int main(){ const int N = 137; Int val(46); Int* A = (Int*) malloc(N * sizeof(Int)); uninitialized_fill_n(A, N, val);}</pre><h3>Notes</h3><P><A name="1">[1]</A>In particular, this sort of low-level memory management is usedin the implementation of some container classes.<h3>See also</h3><A href="Allocators.html">Allocators</A>, <tt><A href="construct.html">construct</A></tt>, <tt><A href="destroy.html">destroy</A></tt>, <tt><A href="uninitialized_copy.html">uninitialized_copy</A></tt>, <tt><A href="uninitialized_fill.html">uninitialized_fill</A></tt>,<tt><A href="raw_storage_iterator.html">raw_storage_iterator</A></tt><!--start footer--> <HR SIZE="6"><A href="http://www.sgi.com/"><IMG SRC="surf.gif" HEIGHT="54" WIDTH="54" ALT="[Silicon Surf]"></A><A HREF="index.html"><IMG SRC="stl_home.gif" HEIGHT="54" WIDTH="54" ALT="[STL Home]"></A><BR><FONT SIZE="-2"><A href="http://www.sgi.com/Misc/sgi_info.html" TARGET="_top">Copyright © 1999 Silicon Graphics, Inc.</A> All Rights Reserved.</FONT><FONT SIZE="-3"><a href="http://www.sgi.com/Misc/external.list.html" TARGET="_top">TrademarkInformation</A></FONT><P></BODY></HTML> ⌨️ 快捷键说明
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