Sorry I can type in Chinese but I can read Chinese, si you can answer the question in Chinese.

My question is that, I select a object, maybe it a text or maybe it a file (e.g. zip file, jpg file...).
So how do I know what am I selected?

Thanks first.

用 filesteam, 開完 file 再睇佢 file format.
唔同 file 會有唔同 header 同 tail,

例如 header two byte
EXE : $4D5A
ZIP : $504B

至於 TEXT file, 係最 basic 既 structure, 佢乜野 contain 就會 save 成乜野, 所以你可以 default 為 text