Question

我正在学习C ++，这是我第一次使用迭代器

我写下了以下代码：

std::pair<max, max> ConvertToAStarMap::GetLimits(std::string map)
{
    // Init max and min variables.
    int max_x = std::numeric_limits<int>::min();
    int min_x = std::numeric_limits<int>::max();

    int max_y = max_x;
    int min_y = min_x;

    std::vector<std::string> map_cells = ConvertToAStarMap::split(map, ';');

    for (std::string::iterator it = map_cells.begin(); it != map_cells.end(); ++it)
}

我收到此错误：

ConvertToAStarMap.cpp: In member function ‘std::pair<max, max> ConvertToAStarMap::GetLimits(std::__cxx11::string)’:
ConvertToAStarMap.cpp:31:52: error: conversion from ‘std::vector<std::__cxx11::basic_string<char> >::iterator {aka __gnu_cxx::__normal_iterator<std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >}’ to non-scalar type ‘std::__cxx11::basic_string<char>::iterator {aka __gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >}’ requested
     for (std::string::iterator it = map_cells.begin(); it != map_cells.end(); ++it)
                                     ~~~~~~~~~~~~~~~^~
ConvertToAStarMap.cpp:31:59: error: no match for ‘operator!=’ (operand types are ‘std::__cxx11::basic_string<char>::iterator {aka __gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >}’ and ‘std::vector<std::__cxx11::basic_string<char> >::iterator {aka __gnu_cxx::__normal_iterator<std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >}’)
     for (std::string::iterator it = map_cells.begin(); it != map_cells.end(); ++it)
                                                        ~~~^~~~~~~~~~~~~~~~~~

怎么了？我不明白。

Answer 1

最容易做到的是：

for (const auto& cell : map_cells)

如果您不想使用基于范围的for循环：

for (auto it = map_cells.begin();......

问题是您要遍历向量，而不是字符串，因此应该是：

for (std::vector<std::string>::iterator it = map_cells.begin();......

此信息在第2点的错误中可用。：

错误：来自
‘std::vector<std::__cxx11::basic_string<char> >::iterator
{aka __gnu_cxx::__normal_iterator<std::__cxx11::basic_string<char>*, std::vector<std::__cxx11::basic_string<char> > >}’
非标量类型
‘std::__cxx11::basic_string<char>::iterator
{aka __gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char> >}’

向量迭代器类型未知

1 个答案: