Re: using std::find

From:
red floyd <no.spam@here.dude>
Newsgroups:
comp.lang.c++
Date:
Wed, 14 Mar 2007 18:14:23 GMT
Message-ID:
<3YWJh.7404$M65.717@newssvr21.news.prodigy.net>
Victor Bazarov wrote:

brekehan wrote:

If I have a class
MyClass
{
  ...bunch o data and methods
  int x;
};

and a stl container of MyClass objects

Is there a way to use std::find to get all the elements whose member x
is of om value?


"om" value? What's "om" value? Sorry, English is not my mother
tongue.

All the example on the net are of a collection of some built in type
for simplicity, but do not show how to use a member of your own type
as the value being sought.


What does your favourite C++ book say? Don't you have a copy of
Josuttis' "The C++ Standard Library"? You can define your own
functor to compare the value of the 'x' member with the given value
and then call

    std::find(container.begin(), container.end(), yourFunctor(42));

V


I think he wants remove_copy_if() with negated functor?

std::vector<MyClass> v;

struct hasElement: public std::unary_function<MyClass, bool>
{
    bool operator()(const MyClass& elem) const
    {
       return elem.x == x;
    }
    hasElement(int x_) : x(x_) { }
private
    int x;
};

std::remove_copy_if(container.begin(), container.end(),
                     std::back_inserter(v),
                     std::not(hasElement(42))_;

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