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My overloading operator

Why doesn't Java offer operator overloading?Storing C++ template function definitions in a .CPP fileConst correctness in C++ operator overloading returnsWhat are the basic rules and idioms for operator overloading?c++ Overload operator bool() gives an ambiguous overload error with operator+overloading operator<< operator== and operator!=Operator overloading in map/pairerror C2678: binary '==' : no operator found which takes a left-hand operand of type (or there is no acceptable conversion)Sorting deque with a functionWhy is const required for 'operator>' but not for 'operator<'?

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3

I want to overload operator < between 2 pair. It works when i compare using < but it doesn't work when i use sort function built_in cpp.
#include
using namespace std;

typedef pair<int,int> pii;

bool operator < (const pii &a,const pii &b)
 return a.second<b.second;


int main()

 pii a,b;
 a=make_pair(1,4);
 b=make_pair(2,3);
 if(a<b) cout<<"a<bn";
 else cout<<"b<an";

 vector<pii> v;
 v.push_back(a);
 v.push_back(b);
 sort(v.begin(),v.end());

 for(auto x:v)
 cerr<<x.first<<" "<<x.second<<endl;

 return 0;

Output:

b<a
1 4
2 3

I 'm confused why it doesn't print:

b<a
2 3
1 4

c++ sorting operator-overloading

share|improve this question

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

add a comment | 

3

I want to overload operator < between 2 pair. It works when i compare using < but it doesn't work when i use sort function built_in cpp.
#include
using namespace std;

typedef pair<int,int> pii;

bool operator < (const pii &a,const pii &b)
 return a.second<b.second;


int main()

 pii a,b;
 a=make_pair(1,4);
 b=make_pair(2,3);
 if(a<b) cout<<"a<bn";
 else cout<<"b<an";

 vector<pii> v;
 v.push_back(a);
 v.push_back(b);
 sort(v.begin(),v.end());

 for(auto x:v)
 cerr<<x.first<<" "<<x.second<<endl;

 return 0;

Output:

b<a
1 4
2 3

I 'm confused why it doesn't print:

b<a
2 3
1 4

c++ sorting operator-overloading

share|improve this question

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

add a comment | 

I want to overload operator < between 2 pair. It works when i compare using < but it doesn't work when i use sort function built_in cpp.
#include
using namespace std;

typedef pair<int,int> pii;

bool operator < (const pii &a,const pii &b)
 return a.second<b.second;


int main()

 pii a,b;
 a=make_pair(1,4);
 b=make_pair(2,3);
 if(a<b) cout<<"a<bn";
 else cout<<"b<an";

 vector<pii> v;
 v.push_back(a);
 v.push_back(b);
 sort(v.begin(),v.end());

 for(auto x:v)
 cerr<<x.first<<" "<<x.second<<endl;

 return 0;

Output:

b<a
1 4
2 3

I 'm confused why it doesn't print:

b<a
2 3
1 4

c++ sorting operator-overloading

share|improve this question

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

typedef pair<int,int> pii;

bool operator < (const pii &a,const pii &b)
 return a.second<b.second;


int main()

 pii a,b;
 a=make_pair(1,4);
 b=make_pair(2,3);
 if(a<b) cout<<"a<bn";
 else cout<<"b<an";

 vector<pii> v;
 v.push_back(a);
 v.push_back(b);
 sort(v.begin(),v.end());

 for(auto x:v)
 cerr<<x.first<<" "<<x.second<<endl;

 return 0;

b<a
1 4
2 3

b<a
2 3
1 4

share|improve this question

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

share|improve this question

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

asked Mar 9 at 9:17

Hieu DoanHieu Doan

224

1 Answer
1

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oldest

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7

std::pair already has a built in operator<. If you want to sort by a different criteria you can pass a comparison function.

std::sort(v.begin(),v.end(), [](auto& lhs, auto& rhs) return lhs.second < rhs.second; );

share|improve this answer

answered Mar 9 at 9:27

supersuper

3,6802818

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thank you very much. It works well.
  
  – Hieu Doan
  Mar 9 at 17:42
  

  
  
  
  

add a comment | 

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7

std::pair already has a built in operator<. If you want to sort by a different criteria you can pass a comparison function.

std::sort(v.begin(),v.end(), [](auto& lhs, auto& rhs) return lhs.second < rhs.second; );

share|improve this answer

answered Mar 9 at 9:27

supersuper

3,6802818

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thank you very much. It works well.
  
  – Hieu Doan
  Mar 9 at 17:42
  

  
  
  
  

add a comment | 

7

std::pair already has a built in operator<. If you want to sort by a different criteria you can pass a comparison function.

std::sort(v.begin(),v.end(), [](auto& lhs, auto& rhs) return lhs.second < rhs.second; );

share|improve this answer

answered Mar 9 at 9:27

supersuper

3,6802818

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  thank you very much. It works well.
  
  – Hieu Doan
  Mar 9 at 17:42
  

  
  
  
  

add a comment | 

std::pair already has a built in operator<. If you want to sort by a different criteria you can pass a comparison function.

std::sort(v.begin(),v.end(), [](auto& lhs, auto& rhs) return lhs.second < rhs.second; );

share|improve this answer

answered Mar 9 at 9:27

supersuper

3,6802818

std::sort(v.begin(),v.end(), [](auto& lhs, auto& rhs) return lhs.second < rhs.second; );

share|improve this answer

answered Mar 9 at 9:27

supersuper

3,6802818

answered Mar 9 at 9:27

supersuper

3,6802818

answered Mar 9 at 9:27

supersuper

3,6802818