gpt4 book ai didi

C++ - 如何使用 reference_wrapper vector

转载 作者:太空狗 更新时间:2023-10-29 20:58:15 30 4
gpt4 key购买 nike

我正在尝试重构我使用指针的寻路算法的一部分,而不是使用指针。不幸的是,我对引用文献不是那么了解。我收到错误:Invalid operands to binary expression ('std::__1::reference_wrapper<Tile>' and 'const std::__1::reference_wrapper<Tile>')

我也不知道那是什么意思。我的代码在下面,我可以收集到它来自以下行:openList.erase(std::find(openList.begin(), openList.end(), current));但我不确定如何解决这个问题。

bool TileMap::tilesBetween(Tile& p_start, Tile& p_end)
{
std::vector<std::reference_wrapper<Tile>> openList;
std::vector<std::reference_wrapper<Tile>> closedList;

openList.push_back(p_start);

do
{
std::sort(openList.begin(), openList.end(), sortF());
Tile& current = openList[0];
closedList.push_back(current);
openList.erase(std::find(openList.begin(), openList.end(), current));
if(std::find(closedList.begin(), closedList.end(), p_end) != closedList.end())
{
return true;
}

std::vector<std::reference_wrapper<Tile>> adjacentTiles;
if (current.m_coordinates.x > 0)
{
adjacentTiles.push_back(m_tiles[current.m_coordinates.y * m_width + (current.m_coordinates.x - 1)]);
}
if (current.m_coordinates.x < m_width)
{
adjacentTiles.push_back(m_tiles[current.m_coordinates.y * m_width + (current.m_coordinates.x + 1)]);
}
if (current.m_coordinates.y > 0)
{
adjacentTiles.push_back(m_tiles[(current.m_coordinates.y - 1) * m_width + current.m_coordinates.x]);
}
if (current.m_coordinates.y < m_height)
{
adjacentTiles.push_back(m_tiles[(current.m_coordinates.y + 1) * m_width + current.m_coordinates.x]);
}

for(auto t : adjacentTiles)
{
if(std::find(closedList.begin(), closedList.end(), t) != closedList.end())
{
continue;
}

if(std::find(openList.begin(), openList.end(), t) == closedList.end())
{
openList.push_back(t);
}
}
}
while(!openList.empty());

return false;
}

编辑:发布sortF

struct sortF
{
bool operator()(const Tile* p_a, const Tile* p_b) const
{
return p_a->f < p_b->f;
}
};

更新:根据建议,我已将函数更改为使用指针而不是引用。它看起来可以正常工作,但在它完成之前我还有更多要实现。

bool TileMap::tilesBetween(Tile* p_start, Tile* p_end)
{
std::vector<Tile*> openList;
std::vector<Tile*> closedList;

std::cout << p_start << ", ";

openList.push_back(p_start);

do
{
std::sort(openList.begin(), openList.end(), sortF());
Tile* current = openList[0];
closedList.push_back(current);
openList.erase(std::find(openList.begin(), openList.end(), current));
if(std::find(closedList.begin(), closedList.end(), p_end) != closedList.end())
{
return true;
}

std::vector<Tile*> adjacentTiles;
if (current->m_coordinates.x > 0)
{
adjacentTiles.push_back(&m_tiles[current->m_coordinates.y * m_width + (current->m_coordinates.x - 1)]);
}
if (current->m_coordinates.x < m_width)
{
std::cout << &m_tiles[current->m_coordinates.y * m_width + (current->m_coordinates.x + 1)] << std::endl;
adjacentTiles.push_back(&m_tiles[current->m_coordinates.y * m_width + (current->m_coordinates.x + 1)]);
}
if (current->m_coordinates.y > 0)
{
adjacentTiles.push_back(&m_tiles[(current->m_coordinates.y - 1) * m_width + current->m_coordinates.x]);
}
if (current->m_coordinates.y < m_height)
{
adjacentTiles.push_back(&m_tiles[(current->m_coordinates.y + 1) * m_width + current->m_coordinates.x]);
}

for(auto t : adjacentTiles)
{
if(std::find(closedList.begin(), closedList.end(), t) != closedList.end())
{
continue;
}

if(std::find(openList.begin(), openList.end(), t) == openList.end())
{
openList.push_back(t);
}
}
}
while(!openList.empty());

return false;
}

最佳答案

I can gather that it comes from the line: openList.erase(std::find(openList.begin(), openList.end(), current)); but I'm not sure how to fix this.

std::find遍历 std::reference_wrapper<Tile>而不是 Tile&本身。因此

    Tile& current = openList[0];
openList.erase(std::find(openList.begin(), openList.end(), current));

不正确。将此更改为

    openList.erase(std::find_if(openList.begin(), openList.end(), [&](const std::reference_wrapper<Tile> &i)
{
return i.get() == current;
}));

std::reference_wrapper::get返回底层引用。

一个简单的,working example证明这一点

#include <algorithm>
#include <list>
#include <vector>
#include <iostream>
#include <functional>

struct S
{
int val;
S(int i) : val(i) {}
};

int main()
{
std::list<S> l = {-4, -3, -2, -1, 0, 1, 2, 3, 4};
std::vector<std::reference_wrapper<S>> v(l.begin(), l.end());

auto& x = l.front();
v.erase(std::find_if(v.cbegin(), v.cend(), [&](const std::reference_wrapper<S> &i)
{
return i.get().val == x.val;
}));
std::cout << v[0].get().val;
}

关于C++ - 如何使用 reference_wrapper vector ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/28080308/

30 4 0
Copyright 2021 - 2024 cfsdn All Rights Reserved 蜀ICP备2022000587号
广告合作:1813099741@qq.com 6ren.com