為什么我的矢量迭代器沒有顯示operator =？

Question

這是計算子陣列的最大總和的函數

int Solution::maxSubArray(const vector<int> &A) {
vector<int>::iterator i;


int max_so_far = *A.begin();
int current_max = *A.begin();


for(i = A.begin(); i != A.end(); ++i)
{   
    current_max = max(*i,*i+current_max);
    max_so_far = max(max_so_far,current_max)
}
return max_so_far;

}

這是錯誤，我得到的是C ++ 11而不是以前的版本。 幫我解決這個問題

solution.cpp: In member function 'int Solution::maxSubArray(const      std::vector<int>&)':
solution.cpp:9:8: error: no match for 'operator=' (operand types are     'std::vector<int>::iterator {aka __gnu_cxx::__normal_iterator<int*,     std::vector<int> >}' and 'std::vector<int>::const_iterator {aka    __gnu_cxx::__normal_iterator<const int*, std::vector<int> >}')
  for(i = A.begin(); i != A.end(); ++i) 
    ^
solution.cpp:9:8: note: candidates are:
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
             from /usr/include/c++/4.8/bits/char_traits.h:39,
             from /usr/include/c++/4.8/ios:40,
             from /usr/include/c++/4.8/ostream:38,
             from /usr/include/c++/4.8/iostream:39,
             from solution.h:7,
             from solution.cpp:-3:
/usr/include/c++/4.8/bits/stl_iterator.h:708:11: note:    __gnu_cxx::__normal_iterator<int*, std::vector<int> >&    __gnu_cxx::__normal_iterator<int*, std::vector<int> >::operator=(const   __gnu_cxx::__normal_iterator<int*, std::vector<int> >&)
     class __normal_iterator
            ^
  /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note:   no known      conversion for argument 1 from 'std::vector<int>::const_iterator {aka   __gnu_cxx::__normal_iterator<const int*, std::vector<int> >}' to 'const   __gnu_cxx::__normal_iterator<int*, std::vector<int> >&'
 /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note:   __gnu_cxx::__normal_iterator<int*, std::vector<int> >& __gnu_cxx::__normal_iterator<int*, std::vector<int> >::operator=    (__gnu_cxx::__normal_iterator<int*, std::vector<int> >&&)
  /usr/include/c++/4.8/bits/stl_iterator.h:708:11: note:   no known      conversion for argument 1 f

Answer 1

您需要使用vector<int>::const_iterator而不是vector<int>::iterator 。

如果您使用的是支持C ++ 11或更高版本的編譯器，則可以使用auto type。

auto i = A.begin();

Answer 2

你不能使用常規迭代器來通過const向量。

vector<int>::iterator i必須是::const_iterator i 。

看到這個問題C ++ STL中const_iterator和非const迭代器有什么區別？

Answer 3

迭代器需要是一個const_iterator因為參數是const vector<int>

---

改變線

vector<int>::iterator i;

至

vector<int>::const_iterator i;

---

或者使用auto來獲取類型

Answer 4

由於您將向量作為const傳遞，因此普通迭代器不會執行此任務。 相反，你需要const_iterator作為const向量 。

int Solution::maxSubArray(const vector<int> &A) {
vector<int>::const_iterator i;
for(i = A.begin(); i != A.end(); ++i)
{   
 ....
}

那應該為你解決！