Symbols for centigrade and plus-or-minus

Do you have the symbol Centigrade, which as I am sure you know is a capital C with a small o
Do you have the symbol for plus and minus, as in, give or take 10 percent. Usually the plus symbol
is above the minus symbol.

Both current answers give excellent advice about how to input characters in Writer; the Unicode character tables site is my “go to” if I’m looking up a particular character. There are lots of other helpful unicode sites, though.

Thank`s Guys. TEA BOY

About unicode: The code points are U+2103 and U+00B1 respectively.
About LibreOffice: In recent versions simply type the 4 hex digits and then immediately Alt+x to enter a unicode character.

2103Alt+x
00B1Alt+x±

There also is U+2213 : 2213Alt+x.

I always use
Insert → Special Character
and make my choice. Both (degree) and (plus-minus) are among the Basic Latin characters. There are other kinds of character available too (math, phonetic, etc). I have not seen (minus-plus) though; so you might have to use Unicode for that.

+1 I’d recommend this method over direct Unicode hex entry because you know for sure which characters are implemented in the font (the actual font is selected with a drop-down menu).

@ve3oat: The ‘PLUS-MINUS SIGN’ U+00B1, as already the code point tells, is listed under ‘Latin-1’.
There is neither the ‘MINUS_OR_PLUS SIGN’ nor the ‘DEGREE CELSIUS’ of unicode in the ‘Latin’ range.
You may, of course, compose something looking like “degrees Centigrade” from two characters.(glyphs).

@ajlittoz: The default font of a newly installed LibO seems to still be ‘Liberation Sans’. This font not has implemented the additional characters mentioned: U+2213 'MINUS_OR_PLUS SIGN' and U+2103 'DEGREE CELSIUS'.
Using a font not containing a unicode character I exceptionally want to insert, I would rather trust in the automatic replacement than search different fonts and judge by eye which one to prefer.

@Lupp: I agree, mixing fonts with differing metrics leads to bad visual result This is not really an issue in formulas (Math component). For plain text, I stay with a symbol font like OpenSymbol when glyph is not available.

Wrt automatic replacement, you frequently end up with the “missing character” glyph, often an empty square, for really “exotic” characters.

For a long time now I was not often annoyed with the missing-character in LibO. Surely I’m not introduced to really exotic charactresses.
(Don’t spread this: My Calc default template’s default cellstyle’s font is ‘DejaVu Sans Mono’. In advance of it I had used ‘Courier New’. Are fix-width fonts strictly unpresentable nowadays?)

@Lupp: My mistake – there is no character set for typographic, phonetic, math, etc. Must have been thinking of something else (too early in the morning!).

Writer:When “-” is at line end and °C on next line it looks like garbage. There use to be a join function or name it to glue 2or more characters together. So far I did not find it. May be in OpenOffice?

To avoid such undesired line wrap, typographic rules say a number with units is composed as number NO-BREAK SPACE (U+00A0) unit symbol. Thus, the whole group is considered an atomic word.

If you don’t like the NO-BREAK SPACE and prefer no space at all, follow the number with a ZERO WIDTH JOINER (U+200D) available with Insert>Formatting Marks>No-width No Break.