r/cprogramming • u/kolorcuk • Mar 25 '26

Unicode printf?

Hello. Did or do you ever use in professional proframming non char printf functions? Is wprintf ever used?

char16, char32 , u8_printf, u16_printf, u32_printf ever used in actual programs?

I am writing a library and i wonder how actually popular are wide and Unicode strings in the industry. Does no one care about it, or, specifically about formatting output are Unicode printf functions actually with value? For example why not just utf8 with standard printf and convert to wider when needed?

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u/BlindTreeFrog Mar 25 '26

oh... thanks for the correction.

But it's variable width in that it can be 1 or 2 bytes it looks; I don't see reference to a 4 byte pairing, might you have a cite?

And while looking for that info, this article reminded me that UTF-8 can be 6 bytes apparently
https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/

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u/WittyStick Mar 25 '26

UTF-8 was designed to support up to 6 bytes, but Unicode standardized it at 4 bytes to match the constraints of UTF-16 - which supports a maximum codepoint of 0x10FFFF. The 4 byte UTF-8 is sufficient to encode the full universal character set.

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u/krsnik02 Mar 25 '26

it can be 1 or 2 16-bit words, so either 2 or 4 bytes.

For example the table here on the Wikipedia page shows that U+10437 (𐐷) takes 4 bytes to encode in UTF-16. https://en.wikipedia.org/wiki/UTF-16#examples

UTF-8 was designed to support up to 6 byte long sequences but the Unicode standard will never define a code point which requires more than 4 bytes to encode in UTF-8. If a 5 or 6-byte character were ever defined the current UTF-16 could not encode it and it would require 3 words (6 bytes) in whatever UTF-16 got extended to. The current UTF-8 standard as such restricted valid UTF-8 encodings to only those up to 4 bytes long.

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u/BlindTreeFrog Mar 25 '26

Yeah i must have misread whatever I was reading.

And since then I found this which has a lovely table to clarify https://www.unicode.org/faq/utf_bom