fork download

copy

#include <iostream>
#include <vector>
#include <functional>
#include <algorithm>
 
using namespace std;
 
class class1
{
private:
  int id;
  double value;
 
public:
class1(int i, double v):id(i), value(v){ }
  int getId()const {return id;}
  double getValue() const {return value;}
};
 
class HasIdentifier:public unary_function<class1, bool>  
{  
public:
    HasIdentifier(int id) : m_id(id) { }  
    bool operator()(const class1& c)const  
    {  
        return (c.getId() == m_id);  
    }  
private:
    int m_id;  
};  
 
 
class class2
{
private:
    vector <class1> objects;
public:
  class2()
  {
    objects.push_back(class1(1, 100.0));
    objects.push_back(class1(2, 100.0));
    objects.push_back(class1(3, 100.0));
  }
 
  double GetValueOfId(int id)
  {
    vector<class1>::iterator itElem = find(objects.begin(), objects.end(), HasIdentifier(id));	
    return itElem->getValue();
  }
};
 
int main() {
 
	class2 c;
 
	int id = 2;
 
	cout<< id << " " << c.GetValueOfId(id);
	return 0;
}
 
 
 
// Then, to find it:

/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h: In function ‘_RandomAccessIterator std::__find(_RandomAccessIterator, _RandomAccessIterator, const _Tp&, std::random_access_iterator_tag) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<class1*, std::vector<class1, std::allocator<class1> > >, _Tp = HasIdentifier]’:
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:3814:   instantiated from ‘_IIter std::find(_IIter, _IIter, const _Tp&) [with _IIter = __gnu_cxx::__normal_iterator<class1*, std::vector<class1, std::allocator<class1> > >, _Tp = HasIdentifier]’
prog.cpp:47:   instantiated from here
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:178: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:3814:   instantiated from ‘_IIter std::find(_IIter, _IIter, const _Tp&) [with _IIter = __gnu_cxx::__normal_iterator<class1*, std::vector<class1, std::allocator<class1> > >, _Tp = HasIdentifier]’
prog.cpp:47:   instantiated from here
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:182: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:186: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:190: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:198: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:202: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’
/usr/lib/gcc/i686-pc-linux-gnu/4.3.4/include/g++-v4/bits/stl_algo.h:206: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = class1*, _Container = std::vector<class1, std::allocator<class1> >]() == __val’

Standard output is empty