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Diffstat (limited to 'runtime/doc/eval.txt')
| -rw-r--r-- | runtime/doc/eval.txt | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt index 5c77c796f..b863f42e6 100644 --- a/runtime/doc/eval.txt +++ b/runtime/doc/eval.txt @@ -1580,6 +1580,33 @@ Examples: > echo $"The square root of {{9}} is {sqrt(9)}" < The square root of {9} is 3.0 ~ + *string-offset-encoding* +A string consists of multiple characters. How the characters are stored +depends on 'encoding'. Most common is UTF-8, which uses one byte for ASCII +characters, two bytes for other latin characters and more bytes for other +characters. + +A string offset can count characters or bytes. Other programs may use +UTF-16 encoding (16-bit words) and an offset of UTF-16 words. Some functions +use byte offsets, usually for UTF-8 encoding. Other functions use character +offsets, in which case the encoding doesn't matter. + +The different offsets for the string "a©😊" are below: + + UTF-8 offsets: + [0]: 61, [1]: C2, [2]: A9, [3]: F0, [4]: 9F, [5]: 98, [6]: 8A + UTF-16 offsets: + [0]: 0061, [1]: 00A9, [2]: D83D, [3]: DE0A + UTF-32 (character) offsets: + [0]: 00000061, [1]: 000000A9, [2]: 0001F60A + +You can use the "g8" and "ga" commands on a character to see the +decimal/hex/octal values. + +The functions |byteidx()|, |utf16idx()| and |charidx()| can be used to convert +between these indices. The functions |strlen()|, |strutf16len()| and +|strcharlen()| return the number of bytes, UTF-16 code units and characters in +a string respectively. option *expr-option* *E112* *E113* ------ |