Characters can consist of multiple code points

Remarks#

An Unicode code point, what programmers often think of one character, often corresponds to what the user thinks is one character. Sometimes however a “character” is made up of multiple code points, as the examples above show.

This means that operations like slicing a string, or getting a character at a given index may not work as expected. For instance the 4^th character of the string "Café" is 'e' (without the accent). Similarly, clipping the string to length 4 will remove the accent.

The technical term for such a group of code points is a grapheme cluster. See UAX #29: Unicode Text Segmentation

Diacritics

A letter with a diacritic may be represented with the letter, and a combining modifier letter. You normally think of é as one character, but it’s really 2 code points:

U+0065 — LATIN SMALL LETTER E
U+0301 — COMBINING ACUTE ACCENT

Similarly ç = c + ¸, and å = a + ˚

combined forms

To complicate matters, there is often a code point for the composed form as well:

"Café" = 'C' + 'a' + 'f' + 'e' + '´'
"Café" = 'C' + 'a' + 'f' + 'é'

Although these strings look the same, they are not equal, and they don’t even have the same length (5 and 4 respectively).

Zalgo Text

There is this thing called Zalgo Text which pushes this to the extreme. Here is the first grapheme cluster of the example. It consists of 15 code points: the Latin letter H and 14 combining marks.

H̡̫̤̤̣͉̤ͭ̓̓̇͗̎̀

Although this doesn’t show up in normal text, it shows that a “character” really can consist of an arbitrary number of code points

Emoji and flags

A lot of emoji consist of more than one code point.

🇯🇵: A flag is defined as a pair of “regional symbol indicator letters” (🇯 + 🇵)
🙋🏿: Some emoji may be followed by a skin tone modifier: 🙋 + 🏿
😀︎ or 😀️: Windows 10 allows you to specify if an emoji is colored or black/white by appending a variation selector (U+FE0E or U+FE0F)
👨‍👩‍👧‍👦: a family. Encoded by joining the emoji for boy, girl, woman and man (👦, 👧, 👩, 👨) together with zero-width joiners (U+200D). On platforms which support it, this is rendered as an emoji of a family with two kids.