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<H2>remove()</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">See Also</A></LI>
<LI><A HREF="#sec8">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 moves all occurrences of a value from a range to the end of the range and returns an iterator pointing to the first moved occurrence</P>
<A NAME="sec3"><H3>Synopsis</H3></A>

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

namespace std {
  template &lt;class ForwardIterator, class T&gt;
  ForwardIterator 
  remove(ForwardIterator start,
         ForwardIterator finish,
         const T&amp; value);
}
</PRE>
<A NAME="sec4"><H3>Description</H3></A>
<P>The <SAMP>remove()</SAMP> algorithm eliminates all the elements referred to by iterator <SAMP>i</SAMP> in the range <SAMP>[start, finish)</SAMP> for which the following condition holds:     <SAMP>*i&nbsp;==&nbsp;value</SAMP>. <SAMP>remove()</SAMP> returns an iterator that points to the end of the resulting range. <SAMP>remove()</SAMP> is stable, which means that the relative order of the elements that are not removed is the same as their relative order in the original range. </P>
<P><SAMP>remove()</SAMP> does not actually reduce the size of the sequence. It actually: 1)&nbsp;copies the values that are to be <I>retained </I>to the front of the sequence, and 2)&nbsp;returns an iterator that describes where the sequence of retained values ends. Elements that follow this iterator are simply the original sequence values, left unchanged. Here's a simple example:</P>
<P>Say we want to remove all values of <SAMP>2</SAMP> from the following sequence:</P>
<P><SAMP>    354621271</SAMP></P>
<P>Applying the <SAMP>remove()</SAMP> algorithm results in the following sequence:</P>
<P><SAMP>    3546171|XX</SAMP></P>
<P>The vertical bar represents the position of the iterator returned by <SAMP>remove()</SAMP>. Note that the elements to the left of the vertical bar are the original sequence with the <SAMP>2</SAMP>s removed. </P>
<P>If you want to actually delete items from the container, use the following technique:</P>
<P><SAMP>container.erase(remove(start,finish,value),container.end());</SAMP></P>
<A NAME="sec5"><H3>Complexity</H3></A>
<P>Exactly <SAMP>finish - start </SAMP>applications of the corresponding predicate are done. </P>
<A NAME="sec6"><H3>Example</H3></A>

<UL><PRE>//
//  remove.cpp
//

#include &lt;algorithm&gt;    // for copy, remove, remove_copy, remove_if
#include &lt;functional&gt;   // for unary_function
#include &lt;iostream&gt;     // for cout, endl
#include &lt;iterator&gt;     // for ostream_iterator
#include &lt;vector&gt;       // for vector

 
template&lt;class Arg&gt;
struct not_zero: public std::unary_function&lt;Arg, bool&gt;
{
    bool operator() (const Arg &amp;a) const {
        return a != 0;
    }
};


int main ()
{
    // For convenience.
    typedef std::vector&lt;int, std::allocator&lt;int&gt; &gt; Vector;
    typedef std::ostream_iterator&lt;int, char,
                                  std::char_traits&lt;char&gt; &gt;
            Iter;

    // Populate a vector with elements from an array.
    const Vector::value_type arr[] = { 1, 2, 3, 4, 5, 
                                       6, 7, 8, 9, 10};
    Vector v (arr + 0, arr + sizeof arr / sizeof *arr);

    // Write out the contents to cout.
    std::copy (v.begin (), v.end (), Iter (std::cout," "));
    std::cout &lt;&lt; std::endl &lt;&lt; std::endl;

    // Move the 7 to the end of the vector.
    Vector::iterator result = std::remove (v.begin (), 
                                           v.end (), 7);

    // Delete the 7 from the vector.
    v.erase (result, v.end ());

    std::copy (v.begin (), v.end (), Iter (std::cout, " "));
    std::cout &lt;&lt; std::endl &lt;&lt; std::endl;

    // Remove all non-zero elements beyond the fourth element.
    v.erase (std::remove_if (v.begin () + 4, v.end (), 
                             not_zero&lt;int&gt; ()), v.end ());

    std::copy (v.begin (), v.end (), Iter (std::cout, " "));
    std::cout &lt;&lt; std::endl &lt;&lt; std::endl;

    // Now remove all 3s on output.
    std::remove_copy (v.begin (), v.end (), 
                      Iter (std::cout, " "), 3);
    std::cout &lt;&lt; std::endl &lt;&lt; std::endl;

    // Now remove everything satisfying predicate on output.
    std::remove_copy_if (v.begin (), v.end (), 
                         Iter (std::cout, " "),
                         not_zero&lt;int&gt;());

    // Return 0 on success, a non-zero value on failure
    return !!v.empty ();
}


Program Output:
</PRE></UL>
<UL><PRE>1 2 3 4 5 6 7 8 9 10 

1 2 3 4 5 6 8 9 10 

1 2 3 4 

1 2 4 

</PRE></UL>
<A NAME="sec7"><H3>See Also</H3></A>
<P><SAMP><A HREF="remove-if.html">remove_if()</A></SAMP>, <SAMP><A HREF="remove-copy.html">remove_copy()</A></SAMP>, <SAMP><A HREF="remove-copy-if.html">remove_copy_if()</A></SAMP></P>
<A NAME="sec8"><H3>Standards Conformance</H3></A>
<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.7</I></P>

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