c - 为什么 C 文件流的开头称为 `SEEK_SET` ？

Question

您可以在 fseek 等函数中使用三个 origin 常量来确定从何处计算您的 offset:SEEK_SET、SEEK_CUR 和 SEEK_END。 SEEK_CUR 和 SEEK_END 似乎不言自明地表示文件流的当前位置和结尾，但为什么 SEEK_SET 用来表示开头？为什么不是像 SEEK_BEG 这样的东西？

Answer 1

因为你可以添加一个偏移量。通过使用 SEEK_SET，您可以显式设置偏移量。 (通过将其添加到开头)

来自 fseek 的联机帮助页:

The new position, measured in bytes, is
obtained by adding offset bytes to the position specified by whence.
If whence is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is
relative to the start of the file, the current position indicator, or
end-of-file, respectively.

来自 lseek 的联机帮助页:

   SEEK_SET
          The file offset is set to offset bytes.

   SEEK_CUR
          The file offset is set to its current location plus offset
          bytes.

   SEEK_END
          The file offset is set to the size of the file plus offset
          bytes.