C++ how to remove duplicates from vector of Class type?

Question

I have a class, the constructor looks like this:

myclass(int=0,string="",int=0,string="",int=0,int=0,
        int=0,int=0,string="",int=0,int=0);

and a vector with elements of this type

vector<myclass>myvect;

the vector is sorted and I am trying to remove duplicates and this is not working:

std::vector<myclass>::iterator it;
   it=std::unique (myvect.begin(), myvect.end());   
   myvect.resize(std::distance(myvect.begin(),it) );

I get this error

:algorithm(1862): error C2678: binary '==' :
 no operator found which takes a left-hand operand 
of type 'myclass' (or there is no acceptable conversion)

any idea why? is there any way I can remove duplicates from this vector?

A simple solution is to implement your own equality operator. — Some programmer dude, May 06 '13 at 17:39

score 3 · Accepted Answer · answered May 06 '13 at 17:41

3

The std::unique algorithm needs to know how to compare two myclass objects for equality. There are two ways you can do this. The first is to implement myclass::operator==. The second is to pass a binary predicate to std::unique:

std::unique (myvect.begin(), myvect.end(),
             [](const myclass& a, const myclass& b) {
               return /* some expression to test equality */;
             });

answered May 06 '13 at 17:41

Joseph Mansfield

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Thanks a lot, my the question was wrong I mean how to remove duplicates. – Sonicpath May 06 '13 at 18:05

score 1 · Answer 2 · answered May 06 '13 at 17:39

1

You probably didn't implement myclass::operator==.

answered May 06 '13 at 17:39

Marc Claesen

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score 1 · Answer 3 · answered May 06 '13 at 17:40

1

You need to overload the operator == for your class myclass in order to apply the unique algorithm.

Quoting from std::unique documentation:

The function uses operator== to compare the pairs of elements (or pred, in version (2)).

answered May 06 '13 at 17:40

taocp

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C++ how to remove duplicates from vector of Class type?

3 Answers3

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