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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>for_each</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>for_each</H1><Table CellPadding=0 CellSpacing=0 width=100%><TR><TD Align=left><Img src = "algorithms.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 VAlign=top><b>Category</b>: algorithms</TD><TD Align=right VAlign=top><b>Component type</b>: function</TD></TR></Table><h3>Prototype</h3><pre>template <class <A href="InputIterator.html">InputIterator</A>, class <A href="UnaryFunction.html">UnaryFunction</A>>UnaryFunction for_each(InputIterator first, InputIterator last, UnaryFunction f);</pre> <h3>Description</h3><tt>For_each</tt> applies the <A href="functors.html">function object</A> <tt>f</tt> to each element in therange <tt>[first, last)</tt>; <tt>f</tt>'s return value, if any, is ignored.Applications are performed in forward order, <i>i.e.</i> from <tt>first</tt> to<tt>last</tt>. <tt>For_each</tt> returns the function object after it has been applied to each element. <A href="#1">[1]</A><h3>Definition</h3>Defined in the standard header <A href="algorithm">algorithm</A>, and in the nonstandardbackward-compatibility header <A href="algo.h">algo.h</A>.<h3>Requirements on types</h3><UL><LI><tt>InputIterator</tt> is a model of <A href="InputIterator.html">Input Iterator</A><LI><tt>UnaryFunction</tt> is a model of <A href="UnaryFunction.html">Unary Function</A><LI><tt>UnaryFunction</tt> does not apply any non-constant operation through its argument.<LI><tt>InputIterator</tt>'s value type is convertible to <tt>UnaryFunction</tt>'s argument type. </UL><h3>Preconditions</h3><UL><LI><tt>[first, last)</tt> is a valid range.</UL><h3>Complexity</h3>Linear. Exactly <tt>last - first</tt> applications of <tt>UnaryFunction</tt>.<h3>Example</h3><pre>template<class T> struct print : public <A href="unary_function.html">unary_function</A><T, void>{ print(ostream& out) : os(out), count(0) {} void operator() (T x) { os << x << ' '; ++count; } ostream& os; int count;};int main(){ int A[] = {1, 4, 2, 8, 5, 7}; const int N = sizeof(A) / sizeof(int); print<int> P = for_each(A, A + N, print<int>(cout)); cout << endl << P.count << " objects printed." << endl;}</pre> <h3>Notes</h3><P><A name="1">[1]</A>This return value is sometimes useful, since a function objectmay have local state. It might, for example, count the number oftimes that it is called, or it might have a status flag to indicatewhether or not a call succeeded.<h3>See also</h3>The <A href="functors.html">function object overview</A>, <tt><A href="count.html">count</A></tt>, <tt><A href="copy.html">copy</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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