cannot open source file "..."

Background：
C++运行环境：#VScode #MinGW-64 #Win10-64.

Error:
1: cannot open source file "string".
2: #include errors detected. Please update your includePath. IntelliSense features for this translation unit (C:\Code\Will\Cpp\selectionSort.cpp) will be provided by the Tag Parser.
3: identifier "string" is undefined". (even have #include <string> and using namespace std;)
4: string is not in std.

//其实这个Error很常见。目前理解是由于编译配置出现问题。
备注：对于Error2也可以在VSCode中File->Preferences->Settings在右侧的自定义配置中添加 "C_Cpp.intelliSenseEngine": "Tag Parser"。但不推荐这样做。

Solution steps:

1. 在cmd中执行 gcc -v -E -x c++ -
2. 复制输出结果中 #include <...> search starts here: 下的所有路径
3. 在VSCode中 Ctrl+Shift+P, 输入Edit Configuration, 打开 c_cpp_properties.json，找到"name":"Win32"。

4. 把第二步复制的路径添加到 c_cpp_properties.json 中的"name":"Win32"下"includePath"和的 "browse"的 "path"中，添加的路径要注有双引号。注意要保持原有顺序！路径中的 .. 不用修改。
   例如：
   "${workspaceRoot}",
   "C:/Program Files (x86)/mingw-w64/i686-7.2.0-posix-dwarf-rt_v5-rev1/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.2.0/include/c++",
   "C:/Program Files (x86)/mingw-w64/i686-7.2.0-posix-dwarf-rt_v5-rev1/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.2.0/include/c++/i686-w64-mingw32",
   "C:/Program Files (x86)/mingw-w64/i686-7.2.0-posix-dwarf-rt_v5-rev1/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.2.0/include/c++/backward",
   "C:/Program Files (x86)/mingw-w64/i686-7.2.0-posix-dwarf-rt_v5-rev1/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.2.0/include",
   "C:/Program Files (x86)/mingw-w64/i686-7.2.0-posix-dwarf-rt_v5-rev1/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.2.0/include-fixed",
   "C:/Program Files (x86)/mingw-w64/i686-7.2.0-posix-dwarf-rt_v5-rev1/mingw32/bin/../lib/gcc/i686-w64-mingw32/7.2.0/../../../../i686-w64-mingw32/include"

       "defines": [
           "_DEBUG",
           "UNICODE",
           "_UNICODE",
           "__GNUC__=7",
           "__cdecl=__attribute__((__cdecl__))"
       ],
       "intelliSenseMode": "clang-x64",

以上内容也可延伸至如何用MinGW和VSCode正确配置一个C++开发环境，特别需要注意在VSCode中.vscode文件夹下的四个配置文件 c_cpp_properties.json, launch.json, settings.json, tasks.json 。

写这篇文章希望对使用C++/MinGW/VSCode初学者有所帮助，少走弯路。
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