~ chicken-core (chicken-5) /manual/Module (chicken string)

  1[[tags: manual]]
  2[[toc:]]
  3
  4== Module (chicken string)
  5
  6This module contains procedures which can perform various useful
  7string operations.
  8
  9=== conc
 10
 11<procedure>(conc X ...)</procedure>
 12
 13Returns a string with the string-represenation of all arguments
 14concatenated together. {{conc}} could be implemented as
 15
 16<enscript highlight=scheme>
 17(define (conc . args)
 18  (apply string-append (map ->string args)) )
 19</enscript>
 20
 21
 22
 23=== ->string
 24
 25<procedure>(->string X)</procedure>
 26
 27Returns a string-representation of {{X}}.
 28
 29
 30=== string-chop
 31
 32<procedure>(string-chop STRING LENGTH)</procedure>
 33
 34Returns a list of substrings taken by ''chopping'' {{STRING}} every {{LENGTH}}
 35characters:
 36
 37<enscript highlight=scheme>
 38(string-chop "one two three" 4)  ==>  ("one " "two " "thre" "e")
 39</enscript>
 40
 41
 42=== string-chomp
 43
 44<procedure>(string-chomp STRING [SUFFIX])</procedure>
 45
 46If {{STRING}} ends with {{SUFFIX}}, then this procedure returns a copy
 47of its first argument with the suffix removed, otherwise returns
 48{{STRING}} unchanged. {{SUFFIX}} defaults to {{"\n"}}.
 49
 50
 51=== string-compare3
 52
 53<procedure>(string-compare3 STRING1 STRING2)</procedure><br>
 54<procedure>(string-compare3-ci STRING1 STRING2)</procedure>
 55
 56Perform a three-way comparison between the {{STRING1}} and {{STRING2}},
 57returning either {{-1}} if {{STRING1}} is lexicographically less
 58than {{STRING2}}, {{0}} if it is equal, or {{1}} if it s greater.
 59{{string-compare3-ci}} performs a case-insensitive comparison.
 60
 61
 62=== string-intersperse
 63
 64<procedure>(string-intersperse LIST [STRING])</procedure>
 65
 66Returns a string that contains all strings in {{LIST}} concatenated
 67together.  {{STRING}} is placed between each concatenated string and
 68defaults to {{" "}}.
 69
 70<enscript highlight=scheme>
 71(string-intersperse '("one" "two") "three")
 72</enscript>
 73
 74is equivalent to
 75
 76<enscript highlight=scheme>
 77(apply string-append (intersperse '("one" "two") "three"))
 78</enscript>
 79
 80
 81=== string-split
 82
 83<procedure>(string-split STRING [DELIMITER-STRING [KEEPEMPTY]])</procedure>
 84
 85Split string into substrings delimited by any of the characters given
 86in the delimiter string. If no delimiters are specified, a string
 87comprising the tab, newline and space characters is assumed. If the
 88parameter {{KEEPEMPTY}} is given and not {{#f}}, then empty substrings
 89are retained:
 90
 91<enscript highlight=scheme>
 92(string-split "one  two  three") ==> ("one" "two" "three")
 93(string-split "foo:bar::baz:" ":" #t) ==> ("foo" "bar" "" "baz" "")
 94(string-split "foo:bar:baz,quux,zot" ":," ) ==> ("foo" "bar" "baz" "quux" "zot")
 95</enscript>
 96
 97
 98=== string-translate
 99
100<procedure>(string-translate STRING FROM [TO])</procedure>
101
102Returns a fresh copy of {{STRING}} with characters matching
103{{FROM}} translated to {{TO}}.  If {{TO}} is omitted, then
104matching characters are removed. {{FROM}} and {{TO}} may be
105a character, a string or a list. If both {{FROM}} and {{TO}}
106are strings, then the character at the same position in {{TO}}
107as the matching character in {{FROM}} is substituted.
108
109
110=== string-translate*
111
112<procedure>(string-translate* STRING SMAP)</procedure>
113
114Substitutes elements of {{STRING}} according to {{SMAP}}.
115{{SMAP}} should be an association-list where each element of the list
116is a pair of the form {{(MATCH . REPLACEMENT)}}. Every occurrence of
117the string {{MATCH}} in {{STRING}} will be replaced by the string
118{{REPLACEMENT}}:
119
120<enscript highlight=scheme>
121(string-translate*
122  "<h1>this is a \"string\"</h1>"
123  '(("<" . "&lt;") (">" . "&gt;") ("\"" . "&quot;")) )
124=>  "&lt;h1&gt;this is a &quot;string&quot;&lt;/h1&gt;"
125</enscript>
126
127
128=== substring=?
129
130<procedure>(substring=? STRING1 STRING2 [START1 [START2 [LENGTH]]])</procedure><br>
131<procedure>(substring-ci=? STRING1 STRING2 [START1 [START2 [LENGTH]]])</procedure>
132
133Returns {{#t}} if the strings {{STRING1}} and {{STRING2}} are equal,
134or {{#f}} otherwise.  The comparison starts at the positions
135{{START1}} and {{START2}} (which default to 0), comparing {{LENGTH}}
136characters (which defaults to the minimum of the remaining length of
137both strings).
138
139
140=== substring-index
141
142<procedure>(substring-index MAYBE-SUBSTRING STRING [START])</procedure><br>
143<procedure>(substring-index-ci MAYBE-SUBSTRING STRING [START])</procedure>
144
145Searches for first index in string {{STRING}} where string
146{{MAYBE-SUBSTRING}} occurs.  If the optional argument {{START}} is given,
147then the search starts at that index.  {{substring-index-ci}}
148is a case-insensitive version of {{substring-index}}.
149
150
151=== reverse-list->string
152
153<procedure>(reverse-list->string LIST)</procedure>
154
155Returns a string with the characters in {{LIST}} in reverse
156order. This is equivalent to {{(list->string (reverse LIST))}}, but
157much more efficient.
158
159
160=== reverse-string-append
161
162<procedure>(reverse-string-append LIST)</procedure>
163
164{{(apply string-append (reverse LIST))}}
165
166
167---
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