Sort a vector of struct based on a specific field

Question

Currently I am trying to sort a vector of structs based on a specific field. I have set up a custom comparison function for the use of the sort function. However, i am getting some errors with it.

Code:

    struct Play{
      int min, down, yard, locat;
      string Description, offname, defname;
      double relevance;
     };

    bool customCompare(const Play &x, const Play &y)
    {
        return (x.relevance < y.relevance);
    }

    void printResults()
    {
        sort(vecData.begin(),vecData.end(), customCompare);
    }`

Errors:

    error C3867: 'List::customCompare': function call missing argument list; use '&List::customCompare' to create a pointer to member
    error C2780: 'void std::sort(_RanIt,_RanIt)' : expects 2 arguments - 3 provided

Make customCompare static.

Kerrek SB
– Kerrek SB

2013-11-23 19:48:05 +00:00
Commented Nov 23, 2013 at 19:48 — Kerrek SB
– Kerrek SB, Commented Nov 23, 2013 at 19:48

Romano Zumbé · Accepted Answer · 2017-07-04 08:03:37Z

6

a) Use sort function with lambda notation as below( if you are using c++11)

 sort(vecData.begin(),vecData.end(), [](const Play &x, const Play &y){ return (x.relevance < y.relevance);});

Working code:

http://ideone.com/bDOrBV

b) Make comparator function as static

http://ideone.com/0HsaaH

edited Jul 4, 2017 at 8:03

Romano Zumbé

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answered Nov 23, 2013 at 19:55

shivakumar

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Comments

L. F. · Accepted Answer · 2019-05-03 11:45:24Z

5

Although this is an old question, I would like to note for the benefit of the future readers the possibility of directly sorting according to a specific field with the help of projections in the upcoming Ranges library in C++20:

ranges::sort(vecData, ranges::less, &Play::relevance);

This avoids the need of specifying two iterators or writing a custom comparison function or lambda.

answered May 3, 2019 at 11:45

L. F.

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Comments

lennon310 · Accepted Answer · 2013-11-23 20:08:46Z

2

static bool customCompare(const Play &x, const Play &y)

edited Nov 23, 2013 at 20:08

answered Nov 23, 2013 at 19:51

lennon310

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