iterator_test.cpp (NG)

iterator_test.cpp

// g++ -std=c++11 iterator_test.cpp

#include <iostream>
#include <vector>
#include <algorithm>

class my_vector {
public:
    std::vector<int> m_vec;
    my_vector(int len, int value) {
	std::vector<int> v(len, value);
        m_vec =	std::move(v);
    }
    std::vector<int>::const_iterator begin() const { return m_vec.begin(); }
    std::vector<int>::const_iterator end() const { return m_vec.end(); }
};

int main(void) {
    const my_vector v(10, 255);
    std::transform(v.begin(), v.end(), v.begin(),
                   [](float val) { return val/10; });
    for (int n : v.m_vec) {
        std::cout << n << ' ';
    }
    return 0;
}

% g++-8  -std=c++11 iterator_test.cpp
In file included from /usr/local/Cellar/gcc/8.2.0/include/c++/8.2.0/algorithm:62,
                 from iterator_test.cpp:5:
/usr/local/Cellar/gcc/8.2.0/include/c++/8.2.0/bits/stl_algo.h: In instantiation of '_OIter std::transform(_IIter, _IIter, _OIter, _UnaryOperation) [with _IIter = __gnu_cxx::__normal_iterator<const int*, std::vector<int> >; _OIter = __gnu_cxx::__normal_iterator<const int*, std::vector<int> >; _UnaryOperation = main()::<lambda(float)>]':
iterator_test.cpp:21:38:   required from here
/usr/local/Cellar/gcc/8.2.0/include/c++/8.2.0/bits/stl_algo.h:4304:12: error: assignment of read-only location '__result.__gnu_cxx::__normal_iterator<const int*, std::vector<int> >::operator*()'
  *__result = __unary_op(*__first);
  ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~