On Thu, 22 Jul 2004 23:00:37 GMT, "BCC" <bryan@akanta.com> wrote:
[color=blue]
>Hi,
>
>I'm looking for some way to do a multiple sort on a vector of objects based
>on the contents of the objects. For example if my vector is of these
>objects:
>
>class MyClass
>{
>public:
> double value1;
> double value2;
> double value3;
>};
>
>So I would want to sort by each value in combination...
>
>Is there an existing function to do this already somewhere? Do I need to
>roll my own? Any suggestions for the fastest algorithm to use for this
>(websites or books)?
>
>Thanks,
>B
>[/color]
#include <algorithm>
#include <vector>
#include <cstdlib>
class MyClass
{
public:
double value1;
double value2;
double value3;
// Friends not necessary with public data,
// required with private data.
friend bool less1(const MyClass& a, const MyClass& b);
friend bool less2(const MyClass& a, const MyClass& b);
friend bool less3(const MyClass& a, const MyClass& b);
friend bool less_sum(const MyClass& a, const MyClass& b);
};
inline bool less1(const MyClass& a, const MyClass& b)
{ return a.value1 < b.value1; }
inline bool less2(const MyClass& a, const MyClass& b)
{ return a.value2 < b.value2; }
inline bool less3(const MyClass& a, const MyClass& b)
{ return a.value3 < b.value3; }
inline bool lessSum(const MyClass& a, const MyClass& b)
{ return (a.value1 + a.value2 + a.value3) < (b.value1 +
b.value2 + b.value3); }
main() {
std::vector<MyClass> mcVec(10);
// Sort by value1
std::sort(mcVec.begin(), mcVec.end(), less1);
// Sort by value2
std::sort(mcVec.begin(), mcVec.end(), less2);
// Sort by value3
std::sort(mcVec.begin(), mcVec.end(), less3);
// Sort by sum of all three values
std::sort(mcVec.begin(), mcVec.end(), lessSum);
return EXIT_SUCCESS;
} // end main()
--
The ultimate truth is that there is no Ultimate Truth
Multiple sort? 
