CODEWITHSUNDEEP
c++structquicksortboolean-operations
Frank Fourlas
Frank Fourlas

Reputation: 121

Sorting multi-variable struct on one of it's variables

Good morning everyone, I'm trying to sort 3 variables connected in a struct based on the values of one of them. To make myself clear I have a structed type of variable called edge and it has 3 ints: edge.a edge.b and edge.w. I want to sort edge by the values on edge.w. I found out that to achieve that i need to use bool operators but i haven't found out how yet. This is my code:

struct type{
   int a,b,w;
   bool operator<(const edge&A) const{
        return w<A.w;
   };
};
type edge[6];
sort (edge);

sort() is included in a library and executes quicksort on the array on parenthesis. Please help, TY

Upvotes: 1

Views: 123

Answers (1)

Vlad from Moscow
Vlad from Moscow

Reputation: 311058

Try the following

#include <algorithm>

//...

struct type{
   int a,b,w;
   bool operator<(const type& A) const{
        return w<A.w;
   };
};

type edge[6];

//...

std::sort( edge, edge + 6 );

Or

#include <algorithm>
#include <iterator>

//...

struct type{
   int a,b,w;
   bool operator<(const type& A) const{
        return w<A.w;
   };
};

type edge[6];

//...

std::sort( std::begin( edge ), std::end( edge ) );

The other approach is the following

#include <algorithm>
#include <iterator>

//...

struct type{
   int a,b,w;

   struct sort_by_a
   {
       bool operator ()(const type &lhs, const type &rhs ) const
       {
           return  lhs.a < rhs.a;
       }
   };
   struct sort_by_b
   {
       bool operator ()(const type &lhs, const type &rhs ) const
       {
           return  lhs.b < rhs.b;
       }
   };
   struct sort_by_w
   {
       bool operator ()(const type &lhs, const type &rhs ) const
       {
           return  lhs.w < rhs.w;
       }
   };
};

type edge[6];

//...

std::sort( std::begin( edge ), std::end( edge ), type::sort_by_a() );
//...
std::sort( std::begin( edge ), std::end( edge ), type::sort_by_b() );
//...
std::sort( std::begin( edge ), std::end( edge ), type::sort_by_w() );

Upvotes: 1

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