/* list_test.cpp
 *
 * This simple test app shows the way I finally found of getting a
 * std::list to be sortable based on a member within the class being
 * inserted into the list. There may well be a better way, but this
 * does at least work.
 *
 * Compile using
 *
 *  gcc -Wall -O2 -o list_test list_test.cpp
 *
 * Run using
 *
 *  ./list_attr
 *
 * It's very simple, but maybe it'll help others out as I spent a bit of
 * time bashing the wall of bricks on this one.
 */

#include <list>
#include <stdio.h>

class number {
public:
	number();
	number(int number);
	number(const number &);
	
	bool operator < (const number &) const;

	void PrintToStream(void);	
private:
	int num;
};

number::number()
{
	num = 0;
}

number::number(int n)
{
	num = n;
}

number::number(const number &n)
{
	num = n.num;
}

void number::PrintToStream(void)
{
	printf("  %4d\n", num);
}

bool number::operator < (const number &n) const
{
	return (n.num > num);
}

struct ltnumber 
{ 
	bool operator()(const number * n1, const number *n2) const 
	{ 
		return (*n1 < *n2); 
	} 
};
 

int main(int argc, char *argv[])
{
	std::list<number *>nums;
	std::list<number *>::iterator it;
	int i;
	
	for (i = 10; i > 0; i--) {
		number *n = new number(i);
		nums.push_back(n);
	}
	printf("Initialised to:\n");
	for (it = nums.begin(); it != nums.end(); it++)
		(*it)->PrintToStream();

	nums.sort( ltnumber() );

	printf("After sort:\n");
	for (it = nums.begin(); it != nums.end(); it++)
		(*it)->PrintToStream();

	return 0;
}