Mega Code Archive
Sorting user-defined class
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#include <algorithm>
#include <functional>
#include <iostream>
#include <vector>
using namespace std;
class MyClass
{
public:
MyClass( int num_points = 0 );
bool operator<( const MyClass& rhs ) const;
int num_points() const;
void print() const;
private:
vector<float> data_;
};
inline
MyClass::MyClass( int num_points ): data_( num_points ){}
inline bool MyClass::operator<( const MyClass& rhs ) const {
return num_points() < rhs.num_points();
}
inline
int MyClass::num_points() const {
return static_cast<int>( data_.size() );
}
inline void MyClass::print() const{
cout << "\nThis experiment has " << num_points() << " data points";
}
bool less_than_iterator( const vector<MyClass>::iterator i,const vector<MyClass>::iterator j );
// evaluate *i < *j
int main( )
{
vector<MyClass> v;
int num_v = 3;
v.reserve( num_v );
v.push_back( MyClass( 3 ) );
v.push_back( MyClass( 9 ) );
v.push_back( MyClass( 5 ) );
for_each( v.begin(), v.end(),mem_fun_ref( &MyClass::print ) );
vector< vector<MyClass>::iterator > iterators( v.size() );
vector< vector<MyClass>::iterator >::iterator j = iterators.begin();
vector<MyClass>::iterator i = v.begin();
vector<MyClass>::iterator v_end = v.end();
while( i != v_end )
*j++ = i++;
sort( iterators.begin(), iterators.end(), less_than_iterator );
vector< vector<MyClass>::iterator >::iterator iterators_end = iterators.end();
for( j = iterators.begin(); j != iterators_end; ++j )
(*j)->print();
for_each( v.begin(), v.end(), mem_fun_ref( &MyClass::print ) );
}
bool less_than_iterator( const vector<MyClass>::iterator i,const vector<MyClass>::iterator j )
{
return *i < *j;
}
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