g ++ 6.2默认标准要求最后包含自定义标题吗？

Question

我正在进行一项由3个文件组成的简单练习; main.cpp，mapgrid.hpp和mapgrid.cpp;如下：

的main.cpp

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include "mapgrid.hpp"

/* main program code */

mapgrid.hpp

#ifndef MAPGRID_HPP
#define MAPGRID_HPP

#include <vector>

struct Point { /* stuff */ };

class MapGrid { /* stuff */ };

#endif // MAPGRID_HPP

mapgrid.cpp

#include "mapgrid.hpp"

#include <cmath>
#include <algorithm>

/* implementation for Point and MapGrid */

当我尝试在没有指定标准的情况下在g ++ 6.2.0中编译上面的文件时，我收到编译错误，说Point does not name a type和no 'bool MapGrid::walkForward(int, bool)' member function delcared in bool MapGrid::walkForward(int, bool)。

奇怪的是，如果我在mapgrid.cpp中切换#includes以使mapgrid.hpp最后出现，程序将正确编译并运行：

#include <cmath>
#include <algorithm>

#include "mapgrid.hpp"

或者如果我使用-std = c ++ 14或-std = c ++ 11标志。我做错了吗？