Question

我正在尝试使用“unique”从vector中删除重复项，但它似乎不起作用。这是我第一次使用迭代器。请告诉我哪里做错了。提前谢谢！

编辑：对p2dvector进行排序，使用unique和erase来查找和删除重复项。但是没有删除重复项。

输出：

X：3和Y：2仍然是重复的。

x: 3

y: 2

x: 6

y: 4

x: 3

y: 2

vector<Point2D> p2dvector;
//vector<Point2D> :: iterator it, it_end;

void readData()
{
    cout<< "Please enter filename : ";
    cin >> inputFile;

    fstream fileStream;
        fileStream.open(inputFile.c_str(),fstream::in);
        int records = 0;

    while( fileStream.good() ) 
    {
        string line = "";
        while (getline (fileStream, line))  
        {   
            stringstream ss (line);
            getline (ss, className, ',');

            if (className == "Point2D")
            {   
                int x, y;
                getline (ss, p2dX, '[');
                getline (ss, p2dX, ',');

                getline (ss, p2dY, ' ');
                getline (ss, p2dY, ']');

                istringstream (p2dX) >> x;
                istringstream (p2dY) >> y;

                Point2D p2d (x, y);
                p2dvector.push_back(p2d);

                            //amended to this
                sort(p2dvector.begin(), p2dvector.end());
                p2dvector.erase(unique(p2dvector.begin(), p2dvector.end()), p2dvector.end());
                /*
                            for (it = p2dvector.begin(); it < p2dvector.end(); it++)
                cout << "before : " << *it;

                it_end = unique(p2dvector.begin(), p2dvector.end());

                for (it = p2dvector.begin(); it < it_end; it++)
                    cout << "removed duplicates : " << *it; */
}
}
}
}

错误:(编辑：使用排序，唯一和擦除后解决此错误，但不删除重复数据）

In file included from /usr/include/c++/4.6/algorithm:63:0,
                 from Assn3.cpp:7:
/usr/include/c++/4.6/bits/stl_algo.h: In function ‘_FIter std::unique(_FIter, _FIter) [with _FIter = __gnu_cxx::__normal_iterator<Point2D*, std::vector<Point2D> >]’:
Assn3.cpp:149:55:   instantiated from here
/usr/include/c++/4.6/bits/stl_algo.h:1189:2: error: no match for ‘operator==’ in ‘__dest.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Point2D*, _Container = std::vector<Point2D>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Point2D&]() == __first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Point2D*, _Container = std::vector<Point2D>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Point2D&]()’

Answer 1

默认情况下，

std::unique调用operator==来比较元素。您需要为Point2D

定义它

 bool operator==(const Point2D& lhs, const Point2D& rhs);

std::unique删除相邻的重复项，如果您要删除所有重复项，则需要对p2dvector进行排序。

如何使用＆＃34; unique＆＃34 ;?从vector中删除重复项？

1 个答案: