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[bpt/emacs.git] / lispref / strings.texi

diff --git a/lispref/strings.texi b/lispref/strings.texi
index 5e511a5..e182451 100644 (file)
--- a/lispref/strings.texi
+++ b/lispref/strings.texi
@@ -1,6 +1,7 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Emacs Lisp Reference Manual.
 @c -*-texinfo-*-
 @c This is part of the GNU Emacs Lisp Reference Manual.

-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc. 
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
+@c   2002, 2003, 2004, 2005, 2006, 2007  Free Software Foundation, Inc.

 @c See the file elisp.texi for copying conditions.
 @setfilename ../info/strings
 @node Strings and Characters, Lists, Numbers, Top
 @c See the file elisp.texi for copying conditions.
 @setfilename ../info/strings
 @node Strings and Characters, Lists, Numbers, Top


@@ -13,8 +14,8 @@
 
   A string in Emacs Lisp is an array that contains an ordered sequence
 of characters.  Strings are used as names of symbols, buffers, and
 
   A string in Emacs Lisp is an array that contains an ordered sequence
 of characters.  Strings are used as names of symbols, buffers, and

-files, to send messages to users, to hold text being copied between
-buffers, and for many other purposes.  Because strings are so important,
+files; to send messages to users; to hold text being copied between
+buffers; and for many other purposes.  Because strings are so important,

 Emacs Lisp has many functions expressly for manipulating them.  Emacs
 Lisp programs use strings more often than individual characters.
 
 Emacs Lisp has many functions expressly for manipulating them.  Emacs
 Lisp programs use strings more often than individual characters.
 


@@ -27,7 +28,7 @@ keyboard character events.
 * Creating Strings::          Functions to allocate new strings.
 * Modifying Strings::         Altering the contents of an existing string.
 * Text Comparison::           Comparing characters or strings.
 * Creating Strings::          Functions to allocate new strings.
 * Modifying Strings::         Altering the contents of an existing string.
 * Text Comparison::           Comparing characters or strings.

-* String Conversion::         Converting characters or strings and vice versa.
+* String Conversion::         Converting to and from characters and strings.

 * Formatting Strings::        @code{format}: Emacs's analogue of @code{printf}.
 * Case Conversion::           Case conversion functions.
 * Case Tables::                      Customizing case conversion.
 * Formatting Strings::        @code{format}: Emacs's analogue of @code{printf}.
 * Case Conversion::           Case conversion functions.
 * Case Tables::                      Customizing case conversion.


@@ -36,15 +37,14 @@ keyboard character events.
 @node String Basics
 @section String and Character Basics
 
 @node String Basics
 @section String and Character Basics
 

-  Strings in Emacs Lisp are arrays that contain an ordered sequence of
-characters.  Characters are represented in Emacs Lisp as integers;
+  Characters are represented in Emacs Lisp as integers;

 whether an integer is a character or not is determined only by how it is
 used.  Thus, strings really contain integers.
 
   The length of a string (like any array) is fixed, and cannot be
 altered once the string exists.  Strings in Lisp are @emph{not}
 terminated by a distinguished character code.  (By contrast, strings in
 whether an integer is a character or not is determined only by how it is
 used.  Thus, strings really contain integers.
 
   The length of a string (like any array) is fixed, and cannot be
 altered once the string exists.  Strings in Lisp are @emph{not}
 terminated by a distinguished character code.  (By contrast, strings in

-C are terminated by a character with @sc{ASCII} code 0.)
+C are terminated by a character with @acronym{ASCII} code 0.)

 
   Since strings are arrays, and therefore sequences as well, you can
 operate on them with the general array and sequence functions.
 
   Since strings are arrays, and therefore sequences as well, you can
 operate on them with the general array and sequence functions.


@@ -52,32 +52,33 @@ operate on them with the general array and sequence functions.
 change individual characters in a string using the functions @code{aref}
 and @code{aset} (@pxref{Array Functions}).
 
 change individual characters in a string using the functions @code{aref}
 and @code{aset} (@pxref{Array Functions}).
 

-  There are two text representations for non-@sc{ASCII} characters in
+  There are two text representations for non-@acronym{ASCII} characters in

 Emacs strings (and in buffers): unibyte and multibyte (@pxref{Text
 Emacs strings (and in buffers): unibyte and multibyte (@pxref{Text

-Representations}).  @sc{ASCII} characters always occupy one byte in a
-string; in fact, there is no real difference between the two
-representation for a string which is all @sc{ASCII}.  For most Lisp
-programming, you don't need to be concerned with these two
+Representations}).  An @acronym{ASCII} character always occupies one byte in a
+string; in fact, when a string is all @acronym{ASCII}, there is no real
+difference between the unibyte and multibyte representations.
+For most Lisp programming, you don't need to be concerned with these two

 representations.
 
   Sometimes key sequences are represented as strings.  When a string is
 a key sequence, string elements in the range 128 to 255 represent meta
 representations.
 
   Sometimes key sequences are represented as strings.  When a string is
 a key sequence, string elements in the range 128 to 255 represent meta

-characters (which are extremely large integers) rather than character
+characters (which are large integers) rather than character

 codes in the range 128 to 255.
 
   Strings cannot hold characters that have the hyper, super or alt
 codes in the range 128 to 255.
 
   Strings cannot hold characters that have the hyper, super or alt

-modifiers; they can hold @sc{ASCII} control characters, but no other
-control characters.  They do not distinguish case in @sc{ASCII} control
+modifiers; they can hold @acronym{ASCII} control characters, but no other
+control characters.  They do not distinguish case in @acronym{ASCII} control

 characters.  If you want to store such characters in a sequence, such as
 a key sequence, you must use a vector instead of a string.
 characters.  If you want to store such characters in a sequence, such as
 a key sequence, you must use a vector instead of a string.

-@xref{Character Type}, for more information about representation of meta
+@xref{Character Type}, for more information about the representation of meta

 and other modifiers for keyboard input characters.
 
   Strings are useful for holding regular expressions.  You can also
 and other modifiers for keyboard input characters.
 
   Strings are useful for holding regular expressions.  You can also

-match regular expressions against strings (@pxref{Regexp Search}).  The
-functions @code{match-string} (@pxref{Simple Match Data}) and
-@code{replace-match} (@pxref{Replacing Match}) are useful for
-decomposing and modifying strings based on regular expression matching.
+match regular expressions against strings with @code{string-match}
+(@pxref{Regexp Search}).  The functions @code{match-string}
+(@pxref{Simple Match Data}) and @code{replace-match} (@pxref{Replacing
+Match}) are useful for decomposing and modifying strings after
+matching regular expressions against them.

 
   Like a buffer, a string can contain text properties for the characters
 in it, as well as the characters themselves.  @xref{Text Properties}.
 
   Like a buffer, a string can contain text properties for the characters
 in it, as well as the characters themselves.  @xref{Text Properties}.


@@ -88,7 +89,7 @@ strings also copy the properties of the characters being copied.
 copy them into buffers.  @xref{Character Type}, and @ref{String Type},
 for information about the syntax of characters and strings.
 @xref{Non-ASCII Characters}, for functions to convert between text
 copy them into buffers.  @xref{Character Type}, and @ref{String Type},
 for information about the syntax of characters and strings.
 @xref{Non-ASCII Characters}, for functions to convert between text

-representations and encode and decode character codes.
+representations and to encode and decode character codes.

 
 @node Predicates for Strings
 @section The Predicates for Strings
 
 @node Predicates for Strings
 @section The Predicates for Strings


@@ -101,6 +102,11 @@ This function returns @code{t} if @var{object} is a string, @code{nil}
 otherwise.
 @end defun
 
 otherwise.
 @end defun
 

+@defun string-or-null-p object
+This function returns @code{t} if @var{object} is a string or nil,
+@code{nil} otherwise.
+@end defun
+

 @defun char-or-string-p object
 This function returns @code{t} if @var{object} is a string or a
 character (i.e., an integer), @code{nil} otherwise.
 @defun char-or-string-p object
 This function returns @code{t} if @var{object} is a string or a
 character (i.e., an integer), @code{nil} otherwise.


@@ -129,7 +135,6 @@ This function returns a string made up of @var{count} repetitions of
 @end defun
 
 @defun string &rest characters
 @end defun
 
 @defun string &rest characters

-@tindex string

 This returns a string containing the characters @var{characters}.
 
 @example
 This returns a string containing the characters @var{characters}.
 
 @example


@@ -159,7 +164,7 @@ position up to which the substring is copied.  The character whose index
 is 3 is actually the fourth character in the string.
 
 A negative number counts from the end of the string, so that @minus{}1
 is 3 is actually the fourth character in the string.
 
 A negative number counts from the end of the string, so that @minus{}1

-signifies the index of the last character of the string.  For example: 
+signifies the index of the last character of the string.  For example:

 
 @example
 @group
 
 @example
 @group


@@ -173,7 +178,7 @@ In this example, the index for @samp{e} is @minus{}3, the index for
 @samp{f} is @minus{}2, and the index for @samp{g} is @minus{}1.
 Therefore, @samp{e} and @samp{f} are included, and @samp{g} is excluded.
 
 @samp{f} is @minus{}2, and the index for @samp{g} is @minus{}1.
 Therefore, @samp{e} and @samp{f} are included, and @samp{g} is excluded.
 

-When @code{nil} is used as an index, it stands for the length of the
+When @code{nil} is used for @var{end}, it stands for the length of the

 string.  Thus,
 
 @example
 string.  Thus,
 
 @example


@@ -201,7 +206,7 @@ Functions}).
 If the characters copied from @var{string} have text properties, the
 properties are copied into the new string also.  @xref{Text Properties}.
 
 If the characters copied from @var{string} have text properties, the
 properties are copied into the new string also.  @xref{Text Properties}.
 

-@code{substring} also allows vectors for the first argument.
+@code{substring} also accepts a vector for the first argument.

 For example:
 
 @example
 For example:
 
 @example


@@ -209,10 +214,11 @@ For example:
      @result{} [b (c)]
 @end example
 
      @result{} [b (c)]
 @end example
 

-A @code{wrong-type-argument} error is signaled if either @var{start} or
-@var{end} is not an integer or @code{nil}.  An @code{args-out-of-range}
-error is signaled if @var{start} indicates a character following
-@var{end}, or if either integer is out of range for @var{string}.
+A @code{wrong-type-argument} error is signaled if @var{start} is not
+an integer or if @var{end} is neither an integer nor @code{nil}.  An
+@code{args-out-of-range} error is signaled if @var{start} indicates a
+character following @var{end}, or if either integer is out of range
+for @var{string}.

 
 Contrast this function with @code{buffer-substring} (@pxref{Buffer
 Contents}), which returns a string containing a portion of the text in
 
 Contrast this function with @code{buffer-substring} (@pxref{Buffer
 Contents}), which returns a string containing a portion of the text in


@@ -220,6 +226,14 @@ the current buffer.  The beginning of a string is at index 0, but the
 beginning of a buffer is at index 1.
 @end defun
 
 beginning of a buffer is at index 1.
 @end defun
 

+@defun substring-no-properties string &optional start end
+This works like @code{substring} but discards all text properties from
+the value.  Also, @var{start} may be omitted or @code{nil}, which is
+equivalent to 0.  Thus, @w{@code{(substring-no-properties
+@var{string})}} returns a copy of @var{string}, with all text
+properties removed.
+@end defun
+

 @defun concat &rest sequences
 @cindex copying strings
 @cindex concatenating strings
 @defun concat &rest sequences
 @cindex copying strings
 @cindex concatenating strings


@@ -247,65 +261,108 @@ returns an empty string.
 The @code{concat} function always constructs a new string that is
 not @code{eq} to any existing string.
 
 The @code{concat} function always constructs a new string that is
 not @code{eq} to any existing string.
 

-When an argument is an integer (not a sequence of integers), it is
-converted to a string of digits making up the decimal printed
-representation of the integer.  @strong{Don't use this feature; we plan
-to eliminate it.  If you already use this feature, change your programs
-now!}  The proper way to convert an integer to a decimal number in this
-way is with @code{format} (@pxref{Formatting Strings}) or
+In Emacs versions before 21, when an argument was an integer (not a
+sequence of integers), it was converted to a string of digits making up
+the decimal printed representation of the integer.  This obsolete usage
+no longer works.  The proper way to convert an integer to its decimal
+printed form is with @code{format} (@pxref{Formatting Strings}) or

 @code{number-to-string} (@pxref{String Conversion}).
 
 @code{number-to-string} (@pxref{String Conversion}).
 

-@example
-@group
-(concat 137)
-     @result{} "137"
-(concat 54 321)
-     @result{} "54321"
-@end group
-@end example
-

 For information about other concatenation functions, see the
 description of @code{mapconcat} in @ref{Mapping Functions},
 For information about other concatenation functions, see the
 description of @code{mapconcat} in @ref{Mapping Functions},

-@code{vconcat} in @ref{Vectors}, and @code{append} in @ref{Building
+@code{vconcat} in @ref{Vector Functions}, and @code{append} in @ref{Building

 Lists}.
 @end defun
 
 Lists}.
 @end defun
 

-@defun split-string string separators
-@tindex split-string
-Split @var{string} into substrings in between matches for the regular
-expression @var{separators}.  Each match for @var{separators} defines a
-splitting point; the substrings between the splitting points are made
-into a list, which is the value.  If @var{separators} is @code{nil} (or
-omitted), the default is @code{"[ \f\t\n\r\v]+"}.
+@defun split-string string &optional separators omit-nulls
+This function splits @var{string} into substrings at matches for the
+regular expression @var{separators}.  Each match for @var{separators}
+defines a splitting point; the substrings between the splitting points
+are made into a list, which is the value returned by
+@code{split-string}.
+
+If @var{omit-nulls} is @code{nil}, the result contains null strings
+whenever there are two consecutive matches for @var{separators}, or a
+match is adjacent to the beginning or end of @var{string}.  If
+@var{omit-nulls} is @code{t}, these null strings are omitted from the
+result.
+
+If @var{separators} is @code{nil} (or omitted),
+the default is the value of @code{split-string-default-separators}.
+
+As a special case, when @var{separators} is @code{nil} (or omitted),
+null strings are always omitted from the result.  Thus:
+
+@example
+(split-string "  two words ")
+     @result{} ("two" "words")
+@end example

 
 

-For example,
+The result is not @code{("" "two" "words" "")}, which would rarely be
+useful.  If you need such a result, use an explicit value for
+@var{separators}:
+
+@example
+(split-string "  two words "
+              split-string-default-separators)
+     @result{} ("" "two" "words" "")
+@end example
+
+More examples:

 
 @example
 (split-string "Soup is good food" "o")
 
 @example
 (split-string "Soup is good food" "o")

-@result{} ("S" "up is g" "" "d f" "" "d")
+     @result{} ("S" "up is g" "" "d f" "" "d")
+(split-string "Soup is good food" "o" t)
+     @result{} ("S" "up is g" "d f" "d")

 (split-string "Soup is good food" "o+")
 (split-string "Soup is good food" "o+")

-@result{} ("S" "up is g" "d f" "d")
+     @result{} ("S" "up is g" "d f" "d")

 @end example
 
 @end example
 

-When there is a match adjacent to the beginning or end of the string,
-this does not cause a null string to appear at the beginning or end
-of the list:
+Empty matches do count, except that @code{split-string} will not look
+for a final empty match when it already reached the end of the string
+using a non-empty match or when @var{string} is empty:

 
 @example
 
 @example

-(split-string "out to moo" "o+")
-@result{} ("ut t" " m")
+(split-string "aooob" "o*")
+     @result{} ("" "a" "" "b" "")
+(split-string "ooaboo" "o*")
+     @result{} ("" "" "a" "b" "")
+(split-string "" "")
+     @result{} ("")

 @end example
 
 @end example
 

-Empty matches do count, when not adjacent to another match:
+However, when @var{separators} can match the empty string,
+@var{omit-nulls} is usually @code{t}, so that the subtleties in the
+three previous examples are rarely relevant:

 
 @example
 
 @example

-(split-string "Soup is good food" "o*")
-@result{}("S" "u" "p" " " "i" "s" " " "g" "d" " " "f" "d")
-(split-string "Nice doggy!" "")
-@result{}("N" "i" "c" "e" " " "d" "o" "g" "g" "y" "!")
+(split-string "Soup is good food" "o*" t)
+     @result{} ("S" "u" "p" " " "i" "s" " " "g" "d" " " "f" "d")
+(split-string "Nice doggy!" "" t)
+     @result{} ("N" "i" "c" "e" " " "d" "o" "g" "g" "y" "!")
+(split-string "" "" t)
+     @result{} nil
+@end example
+
+Somewhat odd, but predictable, behavior can occur for certain
+``non-greedy'' values of @var{separators} that can prefer empty
+matches over non-empty matches.  Again, such values rarely occur in
+practice:
+
+@example
+(split-string "ooo" "o*" t)
+     @result{} nil
+(split-string "ooo" "\\|o+" t)
+     @result{} ("o" "o" "o")

 @end example
 @end defun
 
 @end example
 @end defun
 

+@defvar split-string-default-separators
+The default value of @var{separators} for @code{split-string}.  Its
+usual value is @w{@code{"[ \f\t\n\r\v]+"}}.
+@end defvar
+

 @node Modifying Strings
 @section Modifying Strings
 
 @node Modifying Strings
 @section Modifying Strings
 


@@ -319,15 +376,22 @@ that index, @code{aset} signals an error.
   A more powerful function is @code{store-substring}:
 
 @defun store-substring string idx obj
   A more powerful function is @code{store-substring}:
 
 @defun store-substring string idx obj

-@tindex store-substring

 This function alters part of the contents of the string @var{string}, by
 storing @var{obj} starting at index @var{idx}.  The argument @var{obj}
 may be either a character or a (smaller) string.
 
 Since it is impossible to change the length of an existing string, it is
 an error if @var{obj} doesn't fit within @var{string}'s actual length,
 This function alters part of the contents of the string @var{string}, by
 storing @var{obj} starting at index @var{idx}.  The argument @var{obj}
 may be either a character or a (smaller) string.
 
 Since it is impossible to change the length of an existing string, it is
 an error if @var{obj} doesn't fit within @var{string}'s actual length,

-of if any new character requires a different number of bytes from the
+or if any new character requires a different number of bytes from the

 character currently present at that point in @var{string}.
 character currently present at that point in @var{string}.

+@end defun
+
+  To clear out a string that contained a password, use
+@code{clear-string}:
+
+@defun clear-string string
+This makes @var{string} a unibyte string and clears its contents to
+zeros.  It may also change @var{string}'s length.

 @end defun
 
 @need 2000
 @end defun
 
 @need 2000


@@ -351,7 +415,9 @@ in case if @code{case-fold-search} is non-@code{nil}.
 
 @defun string= string1 string2
 This function returns @code{t} if the characters of the two strings
 
 @defun string= string1 string2
 This function returns @code{t} if the characters of the two strings

-match exactly; case is significant.
+match exactly.  Symbols are also allowed as arguments, in which case
+their print names are used.
+Case is always significant, regardless of @code{case-fold-search}.

 
 @example
 (string= "abc" "abc")
 
 @example
 (string= "abc" "abc")


@@ -366,8 +432,20 @@ The function @code{string=} ignores the text properties of the two
 strings.  When @code{equal} (@pxref{Equality Predicates}) compares two
 strings, it uses @code{string=}.
 
 strings.  When @code{equal} (@pxref{Equality Predicates}) compares two
 strings, it uses @code{string=}.
 

-If the strings contain non-@sc{ASCII} characters, and one is unibyte
-while the other is multibyte, then they cannot be equal.  @xref{Text
+For technical reasons, a unibyte and a multibyte string are
+@code{equal} if and only if they contain the same sequence of
+character codes and all these codes are either in the range 0 through
+127 (@acronym{ASCII}) or 160 through 255 (@code{eight-bit-graphic}).
+However, when a unibyte string gets converted to a multibyte string,
+all characters with codes in the range 160 through 255 get converted
+to characters with higher codes, whereas @acronym{ASCII} characters
+remain unchanged.  Thus, a unibyte string and its conversion to
+multibyte are only @code{equal} if the string is all @acronym{ASCII}.
+Character codes 160 through 255 are not entirely proper in multibyte
+text, even though they can occur.  As a consequence, the situation
+where a unibyte and a multibyte string are @code{equal} without both
+being all @acronym{ASCII} is a technical oddity that very few Emacs
+Lisp programmers ever get confronted with.  @xref{Text

 Representations}.
 @end defun
 
 Representations}.
 @end defun
 


@@ -378,9 +456,9 @@ Representations}.
 @cindex lexical comparison
 @defun string< string1 string2
 @c (findex string< causes problems for permuted index!!)
 @cindex lexical comparison
 @defun string< string1 string2
 @c (findex string< causes problems for permuted index!!)

-This function compares two strings a character at a time.  First it
-scans both the strings at once to find the first pair of corresponding
-characters that do not match.  If the lesser character of those two is
+This function compares two strings a character at a time.  It
+scans both the strings at the same time to find the first pair of corresponding
+characters that do not match.  If the lesser character of these two is

 the character from @var{string1}, then @var{string1} is less, and this
 function returns @code{t}.  If the lesser character is the one from
 @var{string2}, then @var{string1} is greater, and this function returns
 the character from @var{string1}, then @var{string1} is less, and this
 function returns @code{t}.  If the lesser character is the one from
 @var{string2}, then @var{string1} is greater, and this function returns


@@ -388,11 +466,11 @@ function returns @code{t}.  If the lesser character is the one from
 
 Pairs of characters are compared according to their character codes.
 Keep in mind that lower case letters have higher numeric values in the
 
 Pairs of characters are compared according to their character codes.
 Keep in mind that lower case letters have higher numeric values in the

-@sc{ASCII} character set than their upper case counterparts; digits and
+@acronym{ASCII} character set than their upper case counterparts; digits and

 many punctuation characters have a lower numeric value than upper case
 many punctuation characters have a lower numeric value than upper case

-letters.  An @sc{ASCII} character is less than any non-@sc{ASCII}
-character; a unibyte non-@sc{ASCII} character is always less than any
-multibyte non-@sc{ASCII} character (@pxref{Text Representations}).
+letters.  An @acronym{ASCII} character is less than any non-@acronym{ASCII}
+character; a unibyte non-@acronym{ASCII} character is always less than any
+multibyte non-@acronym{ASCII} character (@pxref{Text Representations}).

 
 @example
 @group
 
 @example
 @group


@@ -421,9 +499,12 @@ no characters is less than any other string.
 (string< "abc" "ab")
      @result{} nil
 (string< "" "")
 (string< "abc" "ab")
      @result{} nil
 (string< "" "")

-     @result{} nil                   
+     @result{} nil

 @end group
 @end example
 @end group
 @end example

+
+Symbols are also allowed as arguments, in which case their print names
+are used.

 @end defun
 
 @defun string-lessp string1 string2
 @end defun
 
 @defun string-lessp string1 string2


@@ -431,17 +512,18 @@ no characters is less than any other string.
 @end defun
 
 @defun compare-strings string1 start1 end1 string2 start2 end2 &optional ignore-case
 @end defun
 
 @defun compare-strings string1 start1 end1 string2 start2 end2 &optional ignore-case

-@tindex compare-strings
-This function compares a specified part of @var{string1} with a
+This function compares the specified part of @var{string1} with the

 specified part of @var{string2}.  The specified part of @var{string1}
 specified part of @var{string2}.  The specified part of @var{string1}

-runs from index @var{start1} up to index @var{end1} (default, the end of
-the string).  The specified part of @var{string2} runs from index
-@var{start2} up to index @var{end2} (default, the end of the string).
+runs from index @var{start1} up to index @var{end1} (@code{nil} means
+the end of the string).  The specified part of @var{string2} runs from
+index @var{start2} up to index @var{end2} (@code{nil} means the end of
+the string).

 
 The strings are both converted to multibyte for the comparison
 
 The strings are both converted to multibyte for the comparison

-(@pxref{Text Representations}) so that a unibyte string can be usefully
-compared with a multibyte string.  If @var{ignore-case} is
-non-@code{nil}, then case is ignored as well.
+(@pxref{Text Representations}) so that a unibyte string and its
+conversion to multibyte are always regarded as equal.  If
+@var{ignore-case} is non-@code{nil}, then case is ignored, so that
+upper case letters can be equal to lower case letters.

 
 If the specified portions of the two strings match, the value is
 @code{t}.  Otherwise, the value is an integer which indicates how many
 
 If the specified portions of the two strings match, the value is
 @code{t}.  Otherwise, the value is an integer which indicates how many


@@ -451,24 +533,22 @@ two strings.  The sign is negative if @var{string1} (or its specified
 portion) is less.
 @end defun
 
 portion) is less.
 @end defun
 

-@defun assoc-ignore-case key alist
-@tindex assoc-ignore-case
+@defun assoc-string key alist &optional case-fold

 This function works like @code{assoc}, except that @var{key} must be a
 This function works like @code{assoc}, except that @var{key} must be a

-string, and comparison is done using @code{compare-strings}.
-Case differences are ignored in this comparison.
+string or symbol, and comparison is done using @code{compare-strings}.
+Symbols are converted to strings before testing.
+If @var{case-fold} is non-@code{nil}, it ignores case differences.
+Unlike @code{assoc}, this function can also match elements of the alist
+that are strings or symbols rather than conses.  In particular, @var{alist} can
+be a list of strings or symbols rather than an actual alist.
+@xref{Association Lists}.

 @end defun
 
 @end defun
 

-@defun assoc-ignore-representation key alist
-@tindex assoc-ignore-representation
-This function works like @code{assoc}, except that @var{key} must be a
-string, and comparison is done using @code{compare-strings}.
-Case differences are significant.
-@end defun
-
-  See also @code{compare-buffer-substrings} in @ref{Comparing Text}, for
-a way to compare text in buffers.  The function @code{string-match},
-which matches a regular expression against a string, can be used
-for a kind of string comparison; see @ref{Regexp Search}.
+  See also the @code{compare-buffer-substrings} function in
+@ref{Comparing Text}, for a way to compare text in buffers.  The
+function @code{string-match}, which matches a regular expression
+against a string, can be used for a kind of string comparison; see
+@ref{Regexp Search}.

 
 @node String Conversion
 @comment  node-name,  next,  previous,  up
 
 @node String Conversion
 @comment  node-name,  next,  previous,  up


@@ -476,7 +556,8 @@ for a kind of string comparison; see @ref{Regexp Search}.
 @cindex conversion of strings
 
   This section describes functions for conversions between characters,
 @cindex conversion of strings
 
   This section describes functions for conversions between characters,

-strings and integers.  @code{format} and @code{prin1-to-string}
+strings and integers.  @code{format} (@pxref{Formatting Strings})
+and @code{prin1-to-string}

 (@pxref{Output Functions}) can also convert Lisp objects into strings.
 @code{read-from-string} (@pxref{Input Functions}) can ``convert'' a
 string representation of a Lisp object into an object.  The functions
 (@pxref{Output Functions}) can also convert Lisp objects into strings.
 @code{read-from-string} (@pxref{Input Functions}) can ``convert'' a
 string representation of a Lisp object into an object.  The functions


@@ -486,7 +567,7 @@ text representation of a string (@pxref{Converting Representations}).
   @xref{Documentation}, for functions that produce textual descriptions
 of text characters and general input events
 (@code{single-key-description} and @code{text-char-description}).  These
   @xref{Documentation}, for functions that produce textual descriptions
 of text characters and general input events
 (@code{single-key-description} and @code{text-char-description}).  These

-functions are used primarily for making help messages.
+are used primarily for making help messages.

 
 @defun char-to-string character
 @cindex character to string
 
 @defun char-to-string character
 @cindex character to string


@@ -499,7 +580,7 @@ This function returns a new string containing one character,
 @cindex string to character
   This function returns the first character in @var{string}.  If the
 string is empty, the function returns 0.  The value is also 0 when the
 @cindex string to character
   This function returns the first character in @var{string}.  If the
 string is empty, the function returns 0.  The value is also 0 when the

-first character of @var{string} is the null character, @sc{ASCII} code
+first character of @var{string} is the null character, @acronym{ASCII} code

 0.
 
 @example
 0.
 
 @example


@@ -509,8 +590,10 @@ first character of @var{string} is the null character, @sc{ASCII} code
      @result{} 120
 (string-to-char "")
      @result{} 0
      @result{} 120
 (string-to-char "")
      @result{} 0

+@group

 (string-to-char "\000")
      @result{} 0
 (string-to-char "\000")
      @result{} 0

+@end group

 @end example
 
 This function may be eliminated in the future if it does not seem useful
 @end example
 
 This function may be eliminated in the future if it does not seem useful


@@ -520,16 +603,18 @@ enough to retain.
 @defun number-to-string number
 @cindex integer to string
 @cindex integer to decimal
 @defun number-to-string number
 @cindex integer to string
 @cindex integer to decimal

-This function returns a string consisting of the printed
+This function returns a string consisting of the printed base-ten

 representation of @var{number}, which may be an integer or a floating
 representation of @var{number}, which may be an integer or a floating

-point number.  The value starts with a sign if the argument is
+point number.  The returned value starts with a minus sign if the argument is

 negative.
 
 @example
 (number-to-string 256)
      @result{} "256"
 negative.
 
 @example
 (number-to-string 256)
      @result{} "256"

+@group

 (number-to-string -23)
      @result{} "-23"
 (number-to-string -23)
      @result{} "-23"

+@end group

 (number-to-string -23.5)
      @result{} "-23.5"
 @end example
 (number-to-string -23.5)
      @result{} "-23.5"
 @end example


@@ -543,17 +628,22 @@ See also the function @code{format} in @ref{Formatting Strings}.
 @defun string-to-number string &optional base
 @cindex string to number
 This function returns the numeric value of the characters in
 @defun string-to-number string &optional base
 @cindex string to number
 This function returns the numeric value of the characters in

-@var{string}.  If @var{base} is non-@code{nil}, integers are converted
-in that base.  If @var{base} is @code{nil}, then base ten is used.
-Floating point conversion always uses base ten; we have not implemented
-other radices for floating point numbers, because that would be much
-more work and does not seem useful.
-
-The parsing skips spaces and tabs at the beginning of @var{string}, then
-reads as much of @var{string} as it can interpret as a number.  (On some
-systems it ignores other whitespace at the beginning, not just spaces
-and tabs.)  If the first character after the ignored whitespace is not a
-digit or a plus or minus sign, this function returns 0.
+@var{string}.  If @var{base} is non-@code{nil}, it must be an integer
+between 2 and 16 (inclusive), and integers are converted in that base.
+If @var{base} is @code{nil}, then base ten is used.  Floating point
+conversion only works in base ten; we have not implemented other
+radices for floating point numbers, because that would be much more
+work and does not seem useful.  If @var{string} looks like an integer
+but its value is too large to fit into a Lisp integer,
+@code{string-to-number} returns a floating point result.
+
+The parsing skips spaces and tabs at the beginning of @var{string},
+then reads as much of @var{string} as it can interpret as a number in
+the given base.  (On some systems it ignores other whitespace at the
+beginning, not just spaces and tabs.)  If the first character after
+the ignored whitespace is neither a digit in the given base, nor a
+plus or minus sign, nor the leading dot of a floating point number,
+this function returns 0.

 
 @example
 (string-to-number "256")
 
 @example
 (string-to-number "256")


@@ -564,6 +654,8 @@ digit or a plus or minus sign, this function returns 0.
      @result{} 0
 (string-to-number "-4.5")
      @result{} -4.5
      @result{} 0
 (string-to-number "-4.5")
      @result{} -4.5

+(string-to-number "1e5")
+     @result{} 100000.0

 @end example
 
 @findex string-to-int
 @end example
 
 @findex string-to-int


@@ -592,8 +684,8 @@ Functions}.
 @cindex strings, formatting them
 
   @dfn{Formatting} means constructing a string by substitution of
 @cindex strings, formatting them
 
   @dfn{Formatting} means constructing a string by substitution of

-computed values at various places in a constant string.  This string
-controls how the other values are printed as well as where they appear;
+computed values at various places in a constant string.  This constant string
+controls how the other values are printed, as well as where they appear;

 it is called a @dfn{format string}.
 
   Formatting is often useful for computing messages to be displayed.  In
 it is called a @dfn{format string}.
 
   Formatting is often useful for computing messages to be displayed.  In


@@ -603,9 +695,13 @@ in how they use the result of formatting.
 
 @defun format string &rest objects
 This function returns a new string that is made by copying
 
 @defun format string &rest objects
 This function returns a new string that is made by copying

-@var{string} and then replacing any format specification 
+@var{string} and then replacing any format specification

 in the copy with encodings of the corresponding @var{objects}.  The
 arguments @var{objects} are the computed values to be formatted.
 in the copy with encodings of the corresponding @var{objects}.  The
 arguments @var{objects} are the computed values to be formatted.

+
+The characters in @var{string}, other than the format specifications,
+are copied directly into the output, including their text properties,
+if any.

 @end defun
 
 @cindex @samp{%} in format
 @end defun
 
 @cindex @samp{%} in format


@@ -623,13 +719,24 @@ For example:
 @end group
 @end example
 
 @end group
 @end example
 

+  Since @code{format} interprets @samp{%} characters as format
+specifications, you should @emph{never} pass an arbitrary string as
+the first argument.  This is particularly true when the string is
+generated by some Lisp code.  Unless the string is @emph{known} to
+never include any @samp{%} characters, pass @code{"%s"}, described
+below, as the first argument, and the string as the second, like this:
+
+@example
+  (format "%s" @var{arbitrary-string})
+@end example
+

   If @var{string} contains more than one format specification, the
   If @var{string} contains more than one format specification, the

-format specifications correspond with successive values from
+format specifications correspond to successive values from

 @var{objects}.  Thus, the first format specification in @var{string}
 uses the first such value, the second format specification uses the
 second such value, and so on.  Any extra format specifications (those
 @var{objects}.  Thus, the first format specification in @var{string}
 uses the first such value, the second format specification uses the
 second such value, and so on.  Any extra format specifications (those

-for which there are no corresponding values) cause unpredictable
-behavior.  Any extra values to be formatted are ignored.
+for which there are no corresponding values) cause an error.  Any
+extra values to be formatted are ignored.

 
   Certain format specifications require values of particular types.  If
 you supply a value that doesn't fit the requirements, an error is
 
   Certain format specifications require values of particular types.  If
 you supply a value that doesn't fit the requirements, an error is


@@ -645,7 +752,9 @@ made without quoting (that is, using @code{princ}, not
 by their contents alone, with no @samp{"} characters, and symbols appear
 without @samp{\} characters.
 
 by their contents alone, with no @samp{"} characters, and symbols appear
 without @samp{\} characters.
 

-If there is no corresponding object, the empty string is used.
+If the object is a string, its text properties are
+copied into the output.  The text properties of the @samp{%s} itself
+are also copied, but those of the object take priority.

 
 @item %S
 Replace the specification with the printed representation of the object,
 
 @item %S
 Replace the specification with the printed representation of the object,


@@ -653,8 +762,6 @@ made with quoting (that is, using @code{prin1}---@pxref{Output
 Functions}).  Thus, strings are enclosed in @samp{"} characters, and
 @samp{\} characters appear where necessary before special characters.
 
 Functions}).  Thus, strings are enclosed in @samp{"} characters, and
 @samp{\} characters appear where necessary before special characters.
 

-If there is no corresponding object, the empty string is used.
-

 @item %o
 @cindex integer to octal
 Replace the specification with the base-eight representation of an
 @item %o
 @cindex integer to octal
 Replace the specification with the base-eight representation of an


@@ -665,9 +772,10 @@ Replace the specification with the base-ten representation of an
 integer.
 
 @item %x
 integer.
 
 @item %x

+@itemx %X

 @cindex integer to hexadecimal
 Replace the specification with the base-sixteen representation of an
 @cindex integer to hexadecimal
 Replace the specification with the base-sixteen representation of an

-integer.
+integer.  @samp{%x} uses lower case and @samp{%X} uses upper case.

 
 @item %c
 Replace the specification with the character which is the value given.
 
 @item %c
 Replace the specification with the character which is the value given.


@@ -686,9 +794,9 @@ using either exponential notation or decimal-point notation, whichever
 is shorter.
 
 @item %%
 is shorter.
 
 @item %%

-A single @samp{%} is placed in the string.  This format specification is
-unusual in that it does not use a value.  For example, @code{(format "%%
-%d" 30)} returns @code{"% 30"}.
+Replace the specification with a single @samp{%}.  This format
+specification is unusual in that it does not use a value.  For example,
+@code{(format "%% %d" 30)} returns @code{"% 30"}.

 @end table
 
   Any other format character results in an @samp{Invalid format
 @end table
 
   Any other format character results in an @samp{Invalid format


@@ -704,24 +812,27 @@ operation} error.
 (format "The buffer object prints as %s." (current-buffer))
      @result{} "The buffer object prints as strings.texi."
 
 (format "The buffer object prints as %s." (current-buffer))
      @result{} "The buffer object prints as strings.texi."
 

-(format "The octal value of %d is %o, 
+(format "The octal value of %d is %o,

          and the hex value is %x." 18 18 18)
          and the hex value is %x." 18 18 18)

-     @result{} "The octal value of 18 is 22, 
+     @result{} "The octal value of 18 is 22,

          and the hex value is 12."
 @end group
 @end example
 
          and the hex value is 12."
 @end group
 @end example
 

-@cindex numeric prefix

 @cindex field width
 @cindex padding
 @cindex field width
 @cindex padding

-  All the specification characters allow an optional numeric prefix
-between the @samp{%} and the character.  The optional numeric prefix
-defines the minimum width for the object.  If the printed representation
-of the object contains fewer characters than this, then it is padded.
-The padding is on the left if the prefix is positive (or starts with
-zero) and on the right if the prefix is negative.  The padding character
-is normally a space, but if the numeric prefix starts with a zero, zeros
-are used for padding.  Here are some examples of padding:
+  All the specification characters allow an optional ``width,'' which
+is a digit-string between the @samp{%} and the character.  If the
+printed representation of the object contains fewer characters than
+this width, then it is padded.  The padding is on the left if the
+width is positive (or starts with zero) and on the right if the
+width is negative.  The padding character is normally a space, but if
+the width starts with a zero, zeros are used for padding.  Some of
+these conventions are ignored for specification characters for which
+they do not make sense.  That is, @samp{%s}, @samp{%S} and @samp{%c}
+accept a width starting with 0, but still pad with @emph{spaces} on
+the left.  Also, @samp{%%} accepts a width, but ignores it.  Here are
+some examples of padding:

 
 @example
 (format "%06d is padded on the left with zeros" 123)
 
 @example
 (format "%06d is padded on the left with zeros" 123)


@@ -731,10 +842,9 @@ are used for padding.  Here are some examples of padding:
      @result{} "123    is padded on the right"
 @end example
 
      @result{} "123    is padded on the right"
 @end example
 

-  @code{format} never truncates an object's printed representation, no
-matter what width you specify.  Thus, you can use a numeric prefix to
-specify a minimum spacing between columns with no risk of losing
-information.
+If the width is too small, @code{format} does not truncate the
+object's printed representation.  Thus, you can use a width to specify
+a minimum spacing between columns with no risk of losing information.

 
   In the following three examples, @samp{%7s} specifies a minimum width
 of 7.  In the first case, the string inserted in place of @samp{%7s} has
 
   In the following three examples, @samp{%7s} specifies a minimum width
 of 7.  In the first case, the string inserted in place of @samp{%7s} has


@@ -742,46 +852,74 @@ only 3 letters, so 4 blank spaces are inserted for padding.  In the
 second case, the string @code{"specification"} is 13 letters wide but is
 not truncated.  In the third case, the padding is on the right.
 
 second case, the string @code{"specification"} is 13 letters wide but is
 not truncated.  In the third case, the padding is on the right.
 

-@smallexample 
+@smallexample

 @group
 (format "The word `%7s' actually has %d letters in it."
         "foo" (length "foo"))
 @group
 (format "The word `%7s' actually has %d letters in it."
         "foo" (length "foo"))

-     @result{} "The word `    foo' actually has 3 letters in it."  
+     @result{} "The word `    foo' actually has 3 letters in it."

 @end group
 
 @group
 (format "The word `%7s' actually has %d letters in it."
 @end group
 
 @group
 (format "The word `%7s' actually has %d letters in it."

-        "specification" (length "specification")) 
-     @result{} "The word `specification' actually has 13 letters in it."  
+        "specification" (length "specification"))
+     @result{} "The word `specification' actually has 13 letters in it."

 @end group
 
 @group
 (format "The word `%-7s' actually has %d letters in it."
         "foo" (length "foo"))
 @end group
 
 @group
 (format "The word `%-7s' actually has %d letters in it."
         "foo" (length "foo"))

-     @result{} "The word `foo    ' actually has 3 letters in it."  
+     @result{} "The word `foo    ' actually has 3 letters in it."

 @end group
 @end smallexample
 
 @end group
 @end smallexample
 

+@cindex precision in format specifications
+  All the specification characters allow an optional ``precision''
+before the character (after the width, if present).  The precision is
+a decimal-point @samp{.} followed by a digit-string.  For the
+floating-point specifications (@samp{%e}, @samp{%f}, @samp{%g}), the
+precision specifies how many decimal places to show; if zero, the
+decimal-point itself is also omitted.  For @samp{%s} and @samp{%S},
+the precision truncates the string to the given width, so
+@samp{%.3s} shows only the first three characters of the
+representation for @var{object}.  Precision is ignored for other
+specification characters.
+
+@cindex flags in format specifications
+Immediately after the @samp{%} and before the optional width and
+precision, you can put certain ``flag'' characters.
+
+A space character inserts a space for positive numbers, a plus character
+inserts a plus sign (otherwise nothing is inserted for positive
+numbers).  These flags are ignored except for @samp{%d}, @samp{%e},
+@samp{%f}, @samp{%g}, and if both flags are present the space is
+ignored.
+
+The flag @samp{#} indicates ``alternate form.''  For @samp{%o} it
+ensures that the result begins with a 0.  For @samp{%x} and @samp{%X}
+the result is prefixed with @samp{0x} or @samp{0X}. For @samp{%e},
+@samp{%f}, and @samp{%g} a decimal point is always shown even if the
+precision is zero.
+

 @node Case Conversion
 @node Case Conversion

-@comment node-name, next, previous, up 
+@comment node-name, next, previous, up

 @section Case Conversion in Lisp
 @section Case Conversion in Lisp

-@cindex upper case 
-@cindex lower case 
-@cindex character case 
+@cindex upper case
+@cindex lower case
+@cindex character case

 @cindex case conversion in Lisp
 
   The character case functions change the case of single characters or
 of the contents of strings.  The functions normally convert only
 alphabetic characters (the letters @samp{A} through @samp{Z} and
 @cindex case conversion in Lisp
 
   The character case functions change the case of single characters or
 of the contents of strings.  The functions normally convert only
 alphabetic characters (the letters @samp{A} through @samp{Z} and

-@samp{a} through @samp{z}, as well as non-ASCII letters); other
-characters are not altered.  (You can specify a different case
-conversion mapping by specifying a case table---@pxref{Case Tables}.)
+@samp{a} through @samp{z}, as well as non-@acronym{ASCII} letters); other
+characters are not altered.  You can specify a different case
+conversion mapping by specifying a case table (@pxref{Case Tables}).

 
   These functions do not modify the strings that are passed to them as
 arguments.
 
   The examples below use the characters @samp{X} and @samp{x} which have
 
   These functions do not modify the strings that are passed to them as
 arguments.
 
   The examples below use the characters @samp{X} and @samp{x} which have

-@sc{ASCII} codes 88 and 120 respectively.
+@acronym{ASCII} codes 88 and 120 respectively.

 
 @defun downcase string-or-char
 This function converts a character or a string to lower case.
 
 @defun downcase string-or-char
 This function converts a character or a string to lower case.


@@ -813,7 +951,7 @@ lower case is converted to upper case.
 When the argument to @code{upcase} is a character, @code{upcase}
 returns the corresponding upper case character.  This value is an integer.
 If the original character is upper case, or is not a letter, then the
 When the argument to @code{upcase} is a character, @code{upcase}
 returns the corresponding upper case character.  This value is an integer.
 If the original character is upper case, or is not a letter, then the

-value equals the original character.
+value returned equals the original character.

 
 @example
 (upcase "The cat in the hat")
 
 @example
 (upcase "The cat in the hat")


@@ -835,17 +973,21 @@ case.
 
 The definition of a word is any sequence of consecutive characters that
 are assigned to the word constituent syntax class in the current syntax
 
 The definition of a word is any sequence of consecutive characters that
 are assigned to the word constituent syntax class in the current syntax

-table (@xref{Syntax Class Table}).
+table (@pxref{Syntax Class Table}).

 
 When the argument to @code{capitalize} is a character, @code{capitalize}
 has the same result as @code{upcase}.
 
 @example
 
 When the argument to @code{capitalize} is a character, @code{capitalize}
 has the same result as @code{upcase}.
 
 @example

+@group

 (capitalize "The cat in the hat")
      @result{} "The Cat In The Hat"
 (capitalize "The cat in the hat")
      @result{} "The Cat In The Hat"

+@end group

 
 

+@group

 (capitalize "THE 77TH-HATTED CAT")
      @result{} "The 77th-Hatted Cat"
 (capitalize "THE 77TH-HATTED CAT")
      @result{} "The 77th-Hatted Cat"

+@end group

 
 @group
 (capitalize ?x)
 
 @group
 (capitalize ?x)


@@ -854,15 +996,19 @@ has the same result as @code{upcase}.
 @end example
 @end defun
 
 @end example
 @end defun
 

-@defun upcase-initials string
-This function capitalizes the initials of the words in @var{string}.
-without altering any letters other than the initials.  It returns a new
-string whose contents are a copy of @var{string}, in which each word has
-been converted to upper case.
+@defun upcase-initials string-or-char
+If @var{string-or-char} is a string, this function capitalizes the
+initials of the words in @var{string-or-char}, without altering any
+letters other than the initials.  It returns a new string whose
+contents are a copy of @var{string-or-char}, in which each word has
+had its initial letter converted to upper case.

 
 The definition of a word is any sequence of consecutive characters that
 are assigned to the word constituent syntax class in the current syntax
 
 The definition of a word is any sequence of consecutive characters that
 are assigned to the word constituent syntax class in the current syntax

-table (@xref{Syntax Class Table}).
+table (@pxref{Syntax Class Table}).
+
+When the argument to @code{upcase-initials} is a character,
+@code{upcase-initials} has the same result as @code{upcase}.

 
 @example
 @group
 
 @example
 @group


@@ -918,9 +1064,9 @@ and @samp{A} are related by case-conversion, they should have the same
 canonical equivalent character (which should be either @samp{a} for both
 of them, or @samp{A} for both of them).
 
 canonical equivalent character (which should be either @samp{a} for both
 of them, or @samp{A} for both of them).
 

-  The extra table @var{equivalences} is a map that cyclicly permutes
+  The extra table @var{equivalences} is a map that cyclically permutes

 each equivalence class (of characters with the same canonical
 each equivalence class (of characters with the same canonical

-equivalent).  (For ordinary @sc{ASCII}, this would map @samp{a} into
+equivalent).  (For ordinary @acronym{ASCII}, this would map @samp{a} into

 @samp{A} and @samp{A} into @samp{a}, and likewise for each set of
 equivalent characters.)
 
 @samp{A} and @samp{A} into @samp{a}, and likewise for each set of
 equivalent characters.)
 


@@ -957,7 +1103,7 @@ This sets the current buffer's case table to @var{table}.
 @end defun
 
   The following three functions are convenient subroutines for packages
 @end defun
 
   The following three functions are convenient subroutines for packages

-that define non-@sc{ASCII} character sets.  They modify the specified
+that define non-@acronym{ASCII} character sets.  They modify the specified

 case table @var{case-table}; they also modify the standard syntax table.
 @xref{Syntax Tables}.  Normally you would use these functions to change
 the standard case table.
 case table @var{case-table}; they also modify the standard syntax table.
 @xref{Syntax Tables}.  Normally you would use these functions to change
 the standard case table.


@@ -981,3 +1127,7 @@ This function makes @var{char} case-invariant, with syntax
 This command displays a description of the contents of the current
 buffer's case table.
 @end deffn
 This command displays a description of the contents of the current
 buffer's case table.
 @end deffn

+
+@ignore
+   arch-tag: 700b8e95-7aa5-4b52-9eb3-8f2e1ea152b4
+@end ignore