c++ - 是什么导致 hash_map 错误，我该如何解决？

Question

我正在尝试编译并运行此 GUI 代码:

#include "Simple_window.h" // Get access to our window library
#include "Graph.h" // Get access to our graphics library facilities

int main()
{
    using namespace Graph_lib; // Our graphics facilities are in Graph_lib
    Point tl{ 100, 100 }; // To become top left corner of window
    Simple_window win{ tl, 600, 400, "Canvas" }; // Make a simple window
    Polygon poly; // Make a shape (a polygon)
    poly.add(Point{ 300, 200 }); // Add a point
    poly.add(Point{ 350, 100 }); // Add another point
    poly.add(Point{ 400, 200 }); // Add a third point
    poly.set_color(Color::red); // Adjust properties of poly
    win.attach(poly); // Connect poly to the window
    win.wait_for_button(); // Give control to the display engine
}

header 和代码文件的来源:http://www.stroustrup.com/Programming/PPP2code/

我收到 hash_map 错误

Error (active)    E0035    #error directive: <hash_map> is deprecated and will be REMOVED. Please use <unordered_map>. You can define _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS to acknowledge that you have received this warning.    ConsoleApplication1    C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC\Tools\MSVC\14.24.28314\include\hash_map    21

是什么导致了 hash_map 错误，我该如何解决？

Answer 1

这正是它所说的。

header <hash_map>不是标准的，但是 came from the actual STL .虽然 it currently remains available on your platform ，它“已弃用并将被删除”。

您应该按照消息中的说明进行操作并切换到现代工具，例如 std::unordered_map .不幸的是，这意味着偏离您的原始资料。

我猜测错误本身来自于 fltk(Bjarne 的代码似乎都没有包含该 header ，尽管我只是快速扫描了它)。这些例子非常非常古老。

你可以从a modern book学习C++ , 而不是。

与此同时，如错误消息所述，您可以定义 _SILENCE_STDEXT_HASH_DEPRECATION_WARNINGS (在“预处理器定义”下的项目设置中)暂时确认这一点。

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