c++ - 如何将文件中的 UTF-8 文本转换为可以迭代的容器，并检查每个符号在 C++ 中是否为字母数字？

Answer 1

L"á" means the file was read with a wrong encoding. You have to imbue a UTF-8 locale before reading the stream.

  wifstream input{argv[1]};
  input.imbue(std::locale("en_US.UTF-8"));
  wstring line;
  getline(input, line);

Now wstring line will contain Unicode code points (á in your case) and can be easily iterated.

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Caveat: on Windows wchar_t is deficient (16-bit), and is good enough for iterating over BMP only.