Goofy Unicode problem: mï ¿ ½

I have some text coming into a database that apparently has some sort of Unicode issue. the literal text coming in is "5 mï ¿ ½ in area", which appears to be some sort of unit of measure, but I can't sort out what the meaning is in context. Searching Google shows many similar results, so this is apparently开发者_如何学运维 a common set of symbols.

It's the Unicode replacement character, 0xFFFD (�); see also How to replace � in a string

So I guess the text used to be 5m² in area, and the ² was garbled into � before it arrived in your database.

It's probably supposed to be ² to indicate "meters squared". But you have an encoding problem clearly. I don't know what the problem is because you didn't paste any code or indicate any details for context.