Re: get the max "absolute" integer in a vector

From:
Piyo <cybermax_69@yahoo.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 14 Mar 2007 01:22:00 GMT
Message-ID:
<Y6IJh.5290$Um6.3061@newssvr12.news.prodigy.net>
Piyo wrote:

JDT wrote:

Hi,

Can someone provide me an example that uses std::max_element()
(probablly the predicate version) to return the max "absolute" integer
in a vector? Your help is much appreciated.

Tony

ps.

// return the max integer in a vector
std::vector<int> m;
...
std::vector<int>::iterator p = std::max_element(m.begin(), m.end());


This is the traditional way. You can also attemp to make ComparisonOp
into a template if you wish.

------------------------------------------------
#include <vector>
#include <algorithm>
#include <functional>

class ComparisonOp : public std::binary_function<bool, int, int>
{
public:
    result_type operator()( const first_argument_type &a,
                            const second_argument_type &b ) const
    {
        return (a < b);
    }
};

int
main()
{
    std::vector<int> m;
    // fill m with elements
    std::vector<int>::iterator p = std::max_element(m.begin(), m.end(),
                                                    ComparisonOp());
}
----------------------------------------------------------

This uses boost lambda.
----------------------------------------------------------
#include <vector>
#include <algorithm>
#include <boost/lambda/lambda.hpp>

// this works if operator< is defined for your type (int in your case)

using namespace boost::lambda;

int
main()
{
    std::vector<int> m;
    // fill m with elements
    std::vector<int>::iterator p =
        std::max_element( m.begin(), m.end(), (_1 < _2) );
}

-------------------------------------------------------------

Oops I fogot to put the abs function/fabs if float/double
in there but you get, the idea :)

HTH

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