Sorting a list Structure

[Mike Copeland]

I'm confused about how to sort a list on an element of the list's
structure. Here is my data definition:

struct Finishes // computed Finish information
{
long netTime;
int bibNumber;
} fWork;
typedef list<FinishesFI NISHES;
FINISHES finishInfo;
list<Finishes>: :iterator fIter;

I have populated the list successfully, and now I want to sort the
list on the netTime element. All examples of the list.sort I've found
work only with scalars or single-element structures. How do I do this
with my data? TIA

[Juha Nieminen]

Re: Sorting a list Structure

Mike Copeland wrote:

I'm confused about how to sort a list on an element of the list's
structure. Here is my data definition:
>
struct Finishes // computed Finish information
{
long netTime;
int bibNumber;
} fWork;
typedef list<FinishesFI NISHES;
FINISHES finishInfo;
list<Finishes>: :iterator fIter;
>
I have populated the list successfully, and now I want to sort the
list on the netTime element. All examples of the list.sort I've found
work only with scalars or single-element structures. How do I do this
with my data? TIA

You either define an operator<() in your Finishes struct, or you give
a comparator function to the std::list::sort () function as a parameter.

If comparing objects of type 'Finishes' with the < operator is
rational, that's the easiest solution. In other words, you would do this:

struct Finishes
{
long netTime;
int bibNumber;

bool operator<(const Finishes& rhs) const
{
return netTime < rhs.netTime;
}
};

If the operator < does not make logical sense in the struct and you
would want to avoid it, then you can supply a comparator to the list
sort function:

bool finishesCompara tor(const Finishes& lhs, const Finishes& rhs)
{
return lhs.netTime < rhs.netTime;
}
....

yourList.sort(f inishesComparat or);

[Salt_Peter]

Re: Sorting a list Structure

On Oct 27, 5:19 pm, mrc2...@cox.net (Mike Copeland) wrote:

   I'm confused about how to sort a list on an element of the list's
structure.  Here is my data definition:
>
struct Finishes               // computed Finish information
{
        long  netTime;
        int   bibNumber;} fWork;
>
typedef list<FinishesFI NISHES;
        FINISHES finishInfo;
        list<Finishes>: :iterator fIter;
>
   I have populated the list successfully, and now I want to sort the
list on the netTime element.  All examples of the list.sort I've found
work only with scalars or single-element structures.  How do I do this
with my data?  TIA

Why not use an appropriate container like std::map where netTime is
the key and the integer its values? Elements are then sorted on
insertion using the default comparator less<>.

#include <iostream>
#include <map>

int main()
{
std::map< long, int finishes;
finishes[10L] = 10;
finishes[3L] = 3;
finishes[2L] = 2;
finishes[4L] = 4;
finishes[1L] = 1;
finishes.insert ( std::pair< long, int >(9L, 9) );


typedef std::map< long, int >::iterator MIter;
for( MIter miter = finishes.begin( );
miter != finishes.end();
++miter )
{
std::cout << (*miter).first;
std::cout << "\t";
std::cout << (*miter).second << std::endl;
}

std::cout << "press Enter to EXIT\n";
std::cin.get();
}

/*
1 1
2 2
3 3
4 4
9 9
10 10
*/

[Mike Copeland]

Re: Sorting a list Structure

I have populated the list successfully, and now I want to sort the

list on the netTime element. All examples of the list.sort I've found
work only with scalars or single-element structures. How do I do this
with my data? TIA

>
You either define an operator<() in your Finishes struct, or you give
a comparator function to the std::list::sort () function as a parameter.
>
If comparing objects of type 'Finishes' with the < operator is
rational, that's the easiest solution. In other words, you would do this:
>
struct Finishes
{
long netTime;
int bibNumber;
>
bool operator<(const Finishes& rhs) const
{
return netTime < rhs.netTime;
}
};

Yes, that works perfectly. Thanks!

[Mike Copeland]

Re: Sorting a list Structure

=A0 =A0I'm confused about how to sort a list on an element of the list's

structure. =A0Here is my data definition:

struct Finishes =A0 =A0 =A0 =A0 =A0 =A0 =A0 // computed Finish information
{
=A0 =A0 =A0 =A0 long =A0netTime;
=A0 =A0 =A0 =A0 int =A0 bibNumber;} fWork;

typedef list<FinishesFI NISHES;
=A0 =A0 =A0 =A0 FINISHES finishInfo;
=A0 =A0 =A0 =A0 list<Finishes>: :iterator fIter;

=A0 =A0I have populated the list successfully, and now I want to sort the
list on the netTime element. =A0All examples of the list.sort I've found
work only with scalars or single-element structures. =A0How do I do this
with my data? =A0TIA

>
Why not use an appropriate container like std::map where netTime is
the key and the integer its values? Elements are then sorted on
insertion using the default comparator less<>.

I don't have a need for that. My application just produces Times &
assigns them to bibNumbers; I just need a dynamic array of such data (a
list is fine), and then I sort the data on Time. I don't need to access
any object members randomly, because once I've sorted the array I will
process all objects in that sequence.