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 <H2>transform()</H2>
 <P><B>Library:</B>&nbsp;&nbsp;<A HREF="2-9.html">Algorithms</A></P>

 <PRE><HR><B><I>Function</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">Complexity</A></LI>
 <LI><A HREF="#sec6">Example</A></LI>
 <LI><A HREF="#sec7">Standards Conformance</A></LI>
 </UL>
 <A NAME="sec1"><H3>Local Index</H3></A>
 No Entries
 <A NAME="sec2"><H3>Summary</H3></A>
 <P>Algorithm that applies an operation to a range of values in a collection and stores the result</P>
 <A NAME="sec3"><H3>Synopsis</H3></A>

 <PRE>#include &lt;algorithm&gt;

 namespace std {
   template &lt;class InputIterator, class OutputIterator,
             class UnaryOperation&gt;
   OutputIterator
   transform(InputIterator start, InputIterator finish,
             OutputIterator result, UnaryOperation op);

   template &lt;class InputIterator1, class InputIterator2,
             class OutputIterator, class BinaryOperation&gt;
   OutputIterator
   transform(InputIterator1 start1, InputIterator1 finish1,
             InputIterator2 start2, OutputIterator result,
             BinaryOperation binary_op);
 }
 </PRE>
 <A NAME="sec4"><H3>Description</H3></A>
 <P>The <SAMP>transform()</SAMP> algorithm has two forms. The first form applies unary operation <SAMP>op</SAMP> to each element of the range <SAMP>[start, finish)</SAMP>, and assigns the result to the element pointed to by the output iterator <SAMP>result</SAMP>. For example, this version of <SAMP>transform()</SAMP> could be used to square each element in a <B><I><A HREF="vector.html">vector</A></I></B>. If the output iterator (<SAMP>result</SAMP>) is the same as the input iterator used to traverse the range, <SAMP>transform()</SAMP> performs its transformation in place.</P>
 <P>The second form of <SAMP>transform()</SAMP> applies a binary operation, <SAMP>binary_op</SAMP>, to corresponding elements in the range <SAMP>[start1, finish1)</SAMP> and the range that begins at <SAMP>start2</SAMP>, and assigns the result to the element pointed to by <SAMP>result</SAMP>.   For example, <SAMP>transform()</SAMP> can be used to add corresponding elements in two sequences, and store the set of sums in a third. The algorithm assumes, but does not check, that the second sequence has at least as many elements as the first sequence. Note that the output iterator <SAMP>result</SAMP> can be a third sequence, or either of the two input sequences.</P>
 <P>Formally, <SAMP>transform()</SAMP> assigns through every iterator <SAMP>i</SAMP> in the range <SAMP>[result, result + (finish1 - start1))</SAMP> a new corresponding value equal&nbsp; to:</P>
 <P><SAMP>op(*(start1 + (i - result))</SAMP></P>
 <P>or: </P>
 <P><SAMP>binary_op(*(start1 + (i - result), *(start2 + (i - result)))</SAMP></P>
 <P><SAMP>transform()</SAMP> returns <SAMP>result + (finish1 - start1)</SAMP>.   <SAMP>op</SAMP> and <SAMP>binary_op</SAMP> must not have any side effects. <SAMP>result</SAMP> may be equal to <SAMP>start</SAMP> in case of unary transform, or to <SAMP>start1</SAMP> or <SAMP>start2</SAMP> in case of binary transform. </P>
 <A NAME="sec5"><H3>Complexity</H3></A>
 <P>Exactly <SAMP>finish1 - start1 </SAMP>applications of <SAMP>op</SAMP> or <SAMP>binary_op </SAMP>are performed. </P>
 <A NAME="sec6"><H3>Example</H3></A>

 <UL><PRE>//
 //  trnsform.cpp
 //

 #include &lt;algorithm&gt;    // for transform
 #include &lt;functional&gt;   // for multiplies
 #include &lt;deque&gt;        // for deque
 #include &lt;iostream&gt;     // for cout, endl
 #include &lt;iomanip&gt;      // for setw


 int main ()
 {
     typedef std::deque&lt;int, std::allocator&lt;int&gt; &gt; Deque;

     // Initialize a deque with an array of integers.
     const Deque::value_type a [] = { 99, 264, 126, 330, 132 };
     const Deque::value_type b [] = { 280, 105, 220, 84, 210 };

     Deque d1 (a, a + sizeof a / sizeof *a);
     Deque d2 (b, b + sizeof b / sizeof *b);

     // Print the original values.
     std::cout &lt;&lt; "The following pairs of numbers: \n     ";
     Deque::iterator i1;
     for (i1 = d1.begin(); i1 != d1.end(); ++i1)
         std::cout &lt;&lt; std::setw (6) &lt;&lt; *i1 &lt;&lt; " ";

     std::cout &lt;&lt; "\n     ";
     for (i1 = d2.begin(); i1 != d2.end(); ++i1)
         std::cout &lt;&lt; std::setw (6) &lt;&lt; *i1 &lt;&lt; " ";

     // transform the numbers in one sequence to
     // their factorials and store the results in
     // another sequence
     std::transform (d1.begin (), d1.end (),
                     d2.begin (), d1.begin (),
                     std::multiplies&lt;int&gt;());

     // Display the results.
     std::cout &lt;&lt; "\n\nHave the products: \n     ";
     for (i1 = d1.begin (); i1 != d1.end (); ++i1)
         std::cout &lt;&lt; std::setw (6) &lt;&lt; *i1 &lt;&lt; " ";

     std::cout &lt;&lt; std::endl;

     return 0;
 }


 Program Output:
 </PRE></UL>
 <UL><PRE>The following pairs of numbers:
          99    264    126    330    132
         280    105    220     84    210

 Have the products:
       27720  27720  27720  27720  27720
 </PRE></UL>
 <A NAME="sec7"><H3>Standards Conformance</H3></A>
 <P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.3</I></P>

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	<TITLE>transform()</TITLE>
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	<A HREF="toupper.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="typeinfo-h.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library Reference Guide</B></DIV>
	<H2>transform()</H2>
	<P><B>Library:</B>  <A HREF="2-9.html">Algorithms</A></P>

	<PRE><HR><B><I>Function</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">Complexity</A></LI>
	<LI><A HREF="#sec6">Example</A></LI>
	<LI><A HREF="#sec7">Standards Conformance</A></LI>
	</UL>
	<A NAME="sec1"><H3>Local Index</H3></A>
	No Entries
	<A NAME="sec2"><H3>Summary</H3></A>
	<P>Algorithm that applies an operation to a range of values in a collection and stores the result</P>
	<A NAME="sec3"><H3>Synopsis</H3></A>

	<PRE>#include <algorithm>

	namespace std {
	template <class InputIterator, class OutputIterator,
	class UnaryOperation>
	OutputIterator
	transform(InputIterator start, InputIterator finish,
	OutputIterator result, UnaryOperation op);

	template <class InputIterator1, class InputIterator2,
	class OutputIterator, class BinaryOperation>
	OutputIterator
	transform(InputIterator1 start1, InputIterator1 finish1,
	InputIterator2 start2, OutputIterator result,
	BinaryOperation binary_op);
	}
	</PRE>
	<A NAME="sec4"><H3>Description</H3></A>
	<P>The <SAMP>transform()</SAMP> algorithm has two forms. The first form applies unary operation <SAMP>op</SAMP> to each element of the range <SAMP>[start, finish)</SAMP>, and assigns the result to the element pointed to by the output iterator <SAMP>result</SAMP>. For example, this version of <SAMP>transform()</SAMP> could be used to square each element in a <B><I><A HREF="vector.html">vector</A></I></B>. If the output iterator (<SAMP>result</SAMP>) is the same as the input iterator used to traverse the range, <SAMP>transform()</SAMP> performs its transformation in place.</P>
	<P>The second form of <SAMP>transform()</SAMP> applies a binary operation, <SAMP>binary_op</SAMP>, to corresponding elements in the range <SAMP>[start1, finish1)</SAMP> and the range that begins at <SAMP>start2</SAMP>, and assigns the result to the element pointed to by <SAMP>result</SAMP>. For example, <SAMP>transform()</SAMP> can be used to add corresponding elements in two sequences, and store the set of sums in a third. The algorithm assumes, but does not check, that the second sequence has at least as many elements as the first sequence. Note that the output iterator <SAMP>result</SAMP> can be a third sequence, or either of the two input sequences.</P>
	<P>Formally, <SAMP>transform()</SAMP> assigns through every iterator <SAMP>i</SAMP> in the range <SAMP>[result, result + (finish1 - start1))</SAMP> a new corresponding value equal  to:</P>
	<P><SAMP>op(*(start1 + (i - result))</SAMP></P>
	<P>or: </P>
	<P><SAMP>binary_op((start1 + (i - result), (start2 + (i - result)))</SAMP></P>
	<P><SAMP>transform()</SAMP> returns <SAMP>result + (finish1 - start1)</SAMP>. <SAMP>op</SAMP> and <SAMP>binary_op</SAMP> must not have any side effects. <SAMP>result</SAMP> may be equal to <SAMP>start</SAMP> in case of unary transform, or to <SAMP>start1</SAMP> or <SAMP>start2</SAMP> in case of binary transform. </P>
	<A NAME="sec5"><H3>Complexity</H3></A>
	<P>Exactly <SAMP>finish1 - start1 </SAMP>applications of <SAMP>op</SAMP> or <SAMP>binary_op </SAMP>are performed. </P>
	<A NAME="sec6"><H3>Example</H3></A>

	<UL><PRE>//
	// trnsform.cpp
	//

	#include <algorithm> // for transform
	#include <functional> // for multiplies
	#include <deque> // for deque
	#include <iostream> // for cout, endl
	#include <iomanip> // for setw


	int main ()
	{
	typedef std::deque<int, std::allocator<int> > Deque;

	// Initialize a deque with an array of integers.
	const Deque::value_type a [] = { 99, 264, 126, 330, 132 };
	const Deque::value_type b [] = { 280, 105, 220, 84, 210 };

	Deque d1 (a, a + sizeof a / sizeof *a);
	Deque d2 (b, b + sizeof b / sizeof *b);

	// Print the original values.
	std::cout << "The following pairs of numbers: \n ";
	Deque::iterator i1;
	for (i1 = d1.begin(); i1 != d1.end(); ++i1)
	std::cout << std::setw (6) << *i1 << " ";

	std::cout << "\n ";
	for (i1 = d2.begin(); i1 != d2.end(); ++i1)
	std::cout << std::setw (6) << *i1 << " ";

	// transform the numbers in one sequence to
	// their factorials and store the results in
	// another sequence
	std::transform (d1.begin (), d1.end (),
	d2.begin (), d1.begin (),
	std::multiplies<int>());

	// Display the results.
	std::cout << "\n\nHave the products: \n ";
	for (i1 = d1.begin (); i1 != d1.end (); ++i1)
	std::cout << std::setw (6) << *i1 << " ";

	std::cout << std::endl;

	return 0;
	}



	Program Output:
	</PRE></UL>
	<UL><PRE>The following pairs of numbers:
	99 264 126 330 132
	280 105 220 84 210

	Have the products:
	27720 27720 27720 27720 27720
	</PRE></UL>
	<A NAME="sec7"><H3>Standards Conformance</H3></A>
	<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.3</I></P>

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