Question

int main ()
{
    vector<int> myvector (3,100);

    int myarray [] = { 501,502,503 };
    myvector.insert (myvector.begin(), myarray, myarray+3);

    return 0;
}

That works.

This doesn’t:

typedef struct
{
    float latitude;
    float longitude;
} coordinate;

int main ()
{
    std :: vector <coordinate> previousPoints;

    coordinate start;
    start.latitude  = 22.3;
    start.longitude = 33.4;
    previousPoints.insert (previousPoints.begin (), start, 1);

    return 0;
}

Error:

anisha@linux-trra:~> g++ y.cpp 
y.cpp: In function ‘int main()’:
y.cpp:18:58: error: no matching function for call to ‘std::vector<coordinate>::insert(std::vector<coordinate>::iterator, coordinate&, int)’
/usr/include/c++/4.5/bits/vector.tcc:106:5: note: candidates are: std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(std::vector<_Tp, _Alloc>::iterator, const value_type&) [with _Tp = coordinate, _Alloc = std::allocator<coordinate>, std::vector<_Tp, _Alloc>::iterator = __gnu_cxx::__normal_iterator<coordinate*, std::vector<coordinate> >, typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer = coordinate*, value_type = coordinate]
/usr/include/c++/4.5/bits/stl_vector.h:858:7: note:                 void std::vector<_Tp, _Alloc>::insert(std::vector<_Tp, _Alloc>::iterator, std::vector::size_type, const value_type&) [with _Tp = coordinate, _Alloc = std::allocator<coordinate>, std::vector<_Tp, _Alloc>::iterator = __gnu_cxx::__normal_iterator<coordinate*, std::vector<coordinate> >, typename std::_Vector_base<_Tp, _Alloc>::_Tp_alloc_type::pointer = coordinate*, std::vector::size_type = long unsigned int, value_type = coordinate]
anisha@linux-trra:~>

What’s the error talking about? How are the both examples different?

Answer 1

There is no three parameter std::vector::insert method taking a value as second argument. If you want to insert at the front, you could try

previousPoints.insert(previousPoints.begin(), start);

By the way, if you are going to be performing this operation often, on large vectors, you may want to consider using an std::deque instead, and using it’s push_front method, which has complex time complexity.