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<Title>for_each</Title>
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<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>
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<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 the
range <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 nonstandard
backward-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 object
may have local state. It might, for example, count the number of
times that it is called, or it might have a status flag to indicate
whether 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>
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