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| author | Eli Zaretskii <eliz@gnu.org> | 2012-03-10 11:55:54 +0200 |
|---|---|---|
| committer | Eli Zaretskii <eliz@gnu.org> | 2012-03-10 11:55:54 +0200 |
| commit | 83a96c0872b75177c023b344ce3658d1653d09d4 (patch) | |
| tree | fe07fbe52a2ca7a30914ed36eb896811ffa894da | |
| parent | b9e501dee818df6860341c561f2951699c1e48cc (diff) | |
| download | emacs-83a96c0872b75177c023b344ce3658d1653d09d4.tar.gz emacs-83a96c0872b75177c023b344ce3658d1653d09d4.tar.bz2 emacs-83a96c0872b75177c023b344ce3658d1653d09d4.zip | |
Warn against using `length' to compute display width of a string.
doc/lispref/strings.texi (String Basics):
doc/lispref/sequences.texi (Sequence Functions): Mention that `length' is
not appropriate for computing the string width on display; add a
cross-reference to the description of `string-width'. (Bug#10978)
| -rw-r--r-- | doc/lispref/ChangeLog | 5 | ||||
| -rw-r--r-- | doc/lispref/sequences.texi | 5 | ||||
| -rw-r--r-- | doc/lispref/strings.texi | 4 |
3 files changed, 13 insertions, 1 deletions
diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog index 06d5c541875..201128b9757 100644 --- a/doc/lispref/ChangeLog +++ b/doc/lispref/ChangeLog @@ -1,5 +1,10 @@ 2012-03-10 Eli Zaretskii <eliz@gnu.org> + * strings.texi (String Basics): + * sequences.texi (Sequence Functions): Mention that `length' is + not appropriate for computing the string width on display; add a + cross-reference to the description of `string-width'. (Bug#10978) + * eval.texi (Autoloading): Minor change of wording. 2012-03-10 Chong Yidong <cyd@gnu.org> diff --git a/doc/lispref/sequences.texi b/doc/lispref/sequences.texi index 94f1bf666d2..50f75da2de8 100644 --- a/doc/lispref/sequences.texi +++ b/doc/lispref/sequences.texi @@ -108,6 +108,11 @@ Emacs character code. @noindent See also @code{string-bytes}, in @ref{Text Representations}. +If you need to compute the width of a string on display, you should +use @code{string-width} (@pxref{Width}), not @code{length}, since +@code{length} only counts the number of characters, but does not +account for the display width of each character. + @defun elt sequence index @cindex elements of sequences This function returns the element of @var{sequence} indexed by diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi index bbb75f1474d..64d0986493a 100644 --- a/doc/lispref/strings.texi +++ b/doc/lispref/strings.texi @@ -51,7 +51,9 @@ C are terminated by a character with @acronym{ASCII} code 0.) operate on them with the general array and sequence functions. (@xref{Sequences Arrays Vectors}.) For example, you can access or change individual characters in a string using the functions @code{aref} -and @code{aset} (@pxref{Array Functions}). +and @code{aset} (@pxref{Array Functions}). However, note that +@code{length} should @emph{not} be used for computing the width of a +string on display; use @code{string-width} (@pxref{Width}) instead. There are two text representations for non-@acronym{ASCII} characters in Emacs strings (and in buffers): unibyte and multibyte (@pxref{Text |