regex - GNU grep regex `[一十]`（1から10）は漢字四（4）と一致しません

Answer 1

The Chinese numbers are not in order in Unicode. That 四 is U+56DB, while 一 is U+4E00, and 10 is 5341. So the 4 doesn't fit.

Read the Unicode standard for more information, and see http://www.unicode.org/charts/PDF/U4E00.pdf.

Answer 2

I asked this on a Chinese forum, and alvin_rxg replies with this:

一 => U+4E00
十 => U+5341
四 => U+56DB

So I known I just made a silly assumption! grep is not that smart. The regex [一-十] (one to ten) is not expected to match against Chinese numbers. It just matches any characters between '一' (U+4E00) and '十' (U+5341). It just happens that all Chinese numbers are in that range except '四' (U+56DB)!

This can be used as a cold joke, though. ;-)