Tcl Built-In Commands string(1T)
NAME
string - Manipulate strings
SYNOPSIS
string option arg ?arg ...?
DESCRIPTION
Performs one of several string operations, depending on
option. The legal options (which may be abbreviated) are:
string bytelength string
Returns a decimal string giving the number of bytes
used to represent string in memory. Because UTF-8 uses
one to three bytes to represent Unicode characters, the
byte length will not be the same as the character
length in general. The cases where a script cares
about the byte length are rare. In almost all cases,
you should use the string length operation (including
determining the length of a Tcl ByteArray object).
Refer to the TclNumUtfChars manual entry for more
details on the UTF-8 representation.
string compare ?-nocase? ?-length int? string1 string2
Perform a character-by-character comparison of strings
string1 and string2. Returns -1, 0, or 1, depending on
whether string1 is lexicographically less than, equal
to, or greater than string2. If -length is specified,
then only the first length characters are used in the
comparison. If -length is negative, it is ignored. If
-nocase is specified, then the strings are compared in
a case-insensitive manner.
string equal ?-nocase? ?-length int? string1 string2
Perform a character-by-character comparison of strings
string1 and string2. Returns 1 if string1 and string2
are identical, or 0 when not. If -length is specified,
then only the first length characters are used in the
comparison. If -length is negative, it is ignored. If
-nocase is specified, then the strings are compared in
a case-insensitive manner.
string first string1 string2 ?startIndex?
Search string2 for a sequence of characters that
exactly match the characters in string1. If found,
return the index of the first character in the first
such match within string2. If not found, return -1.
If startIndex is specified (in any of the forms
accepted by the index method), then the search is
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Tcl Built-In Commands string(1T)
constrained to start with the character in string2
specified by the index. For example,
string first a 0a23456789abcdef 5
will return 10, but
string first a 0123456789abcdef 11
will return -1.
string index string charIndex
Returns the charIndex'th character of the string argu-
ment. A charIndex of 0 corresponds to the first char-
acter of the string. charIndex may be specified as
follows:
integer The char specified at this integral index.
end The last char of the string.
end-integer
The last char of the string minus the speci-
fied integer offset (e.g. end-1 would refer
to the "c" in "abcd").
If charIndex is less than 0 or greater than or equal to
the length of the string then an empty string is
returned.
string is class ?-strict? ?-failindex varname? string
Returns 1 if string is a valid member of the specified
character class, otherwise returns 0. If -strict is
specified, then an empty string returns 0, otherwise
and empty string will return 1 on any class. If -fail-
index is specified, then if the function returns 0, the
index in the string where the class was no longer valid
will be stored in the variable named varname. The var-
name will not be set if the function returns 1. The
following character classes are recognized (the class
name can be abbreviated):
alnum Any Unicode alphabet or digit character.
alpha Any Unicode alphabet character.
ascii Any character with a value less than \u0080
(those that are in the 7-bit ascii range).
boolean Any of the forms allowed to TclGetBoolean.
control Any Unicode control character.
digit Any Unicode digit character. Note that
this includes characters outside of the
[0-9] range.
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Tcl Built-In Commands string(1T)
double Any of the valid forms for a double in Tcl,
with optional surrounding whitespace. In
case of under/overflow in the value, 0 is
returned and the varname will contain -1.
false Any of the forms allowed to TclGetBoolean
where the value is false.
graph Any Unicode printing character, except
space.
integer Any of the valid forms for an ordinary
integer in Tcl, with optional surrounding
whitespace. In case of under/overflow in
the value, 0 is returned and the varname
will contain -1.
lower Any Unicode lower case alphabet character.
print Any Unicode printing character, including
space.
punct Any Unicode punctuation character.
space Any Unicode space character.
true Any of the forms allowed to TclGetBoolean
where the value is true.
upper Any upper case alphabet character in the
Unicode character set.
wordchar Any Unicode word character. That is any
alphanumeric character, and any Unicode
connector punctuation characters (e.g.
underscore).
xdigit Any hexadecimal digit character
([0-9A-Fa-f]).
In the case of boolean, true and false, if the function
will return 0, then the varname will always be set to
0, due to the varied nature of a valid boolean value.
string last string1 string2 ?lastIndex?
Search string2 for a sequence of characters that
exactly match the characters in string1. If found,
return the index of the first character in the last
such match within string2. If there is no match, then
return -1. If lastIndex is specified (in any of the
forms accepted by the index method), then only the
characters in string2 at or before the specified
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Tcl Built-In Commands string(1T)
lastIndex will be considered by the search. For exam-
ple,
string last a 0a23456789abcdef 15
will return 10, but
string last a 0a23456789abcdef 9
will return 1.
string length string
Returns a decimal string giving the number of charac-
ters in string. Note that this is not necessarily the
same as the number of bytes used to store the string.
If the object is a ByteArray object (such as those
returned from reading a binary encoded channel), then
this will return the actual byte length of the object.
string map ?-nocase? mapping string
Replaces substrings in string based on the key-value
pairs in mapping. mapping is a list of key value key
value ... as in the form returned by array get. Each
instance of a key in the string will be replaced with
its corresponding value. If -nocase is specified, then
matching is done without regard to case differences.
Both key and value may be multiple characters.
Replacement is done in an ordered manner, so the key
appearing first in the list will be checked first, and
so on. string is only iterated over once, so earlier
key replacements will have no affect for later key
matches. For example,
string map {abc 1 ab 2 a 3 1 0} 1abcaababcabababc
will return the string 01321221.
Note that if an earlier key is a prefix of a later one,
it will completely mask the later one. So if the pre-
vious example is reordered like this,
string map {1 0 ab 2 a 3 abc 1} 1abcaababcabababc
it will return the string 02c322c222c.
string match ?-nocase? pattern string
See if pattern matches string; return 1 if it does, 0
if it doesn't. If -nocase is specified, then the pat-
tern attempts to match against the string in a case
insensitive manner. For the two strings to match,
their contents must be identical except that the fol-
lowing special sequences may appear in pattern:
* Matches any sequence of characters in string,
including a null string.
? Matches any single character in string.
[chars] Matches any character in the set given by
chars. If a sequence of the form x-y appears
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Tcl Built-In Commands string(1T)
in chars, then any character between x and y,
inclusive, will match. When used with
-nocase, the end points of the range are con-
verted to lower case first. Whereas {[A-z]}
matches '' when matching case-sensitively
('' falls between the 'Z' and 'a'), with
-nocase this is considered like {[A-Za-z]}
(and probably what was meant in the first
place).
\x Matches the single character x. This pro-
vides a way of avoiding the special interpre-
tation of the characters *?[]\ in pattern.
string range string first last
Returns a range of consecutive characters from string,
starting with the character whose index is first and
ending with the character whose index is last. An index
of 0 refers to the first character of the string.
first and last may be specified as for the index
method. If first is less than zero then it is treated
as if it were zero, and if last is greater than or
equal to the length of the string then it is treated as
if it were end. If first is greater than last then an
empty string is returned.
string repeat string count
Returns string repeated count number of times.
string replace string first last ?newstring?
Removes a range of consecutive characters from string,
starting with the character whose index is first and
ending with the character whose index is last. An
index of 0 refers to the first character of the string.
First and last may be specified as for the index
method. If newstring is specified, then it is placed
in the removed character range. If first is less than
zero then it is treated as if it were zero, and if last
is greater than or equal to the length of the string
then it is treated as if it were end. If first is
greater than last or the length of the initial string,
or last is less than 0, then the initial string is
returned untouched.
string tolower string ?first? ?last?
Returns a value equal to string except that all upper
(or title) case letters have been converted to lower
case. If first is specified, it refers to the first
char index in the string to start modifying. If last
is specified, it refers to the char index in the string
to stop at (inclusive). first and last may be speci-
fied as for the index method.
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Tcl Built-In Commands string(1T)
string totitle string ?first? ?last?
Returns a value equal to string except that the first
character in string is converted to its Unicode title
case variant (or upper case if there is no title case
variant) and the rest of the string is converted to
lower case. If first is specified, it refers to the
first char index in the string to start modifying. If
last is specified, it refers to the char index in the
string to stop at (inclusive). first and last may be
specified as for the index method.
string toupper string ?first? ?last?
Returns a value equal to string except that all lower
(or title) case letters have been converted to upper
case. If first is specified, it refers to the first
char index in the string to start modifying. If last
is specified, it refers to the char index in the string
to stop at (inclusive). first and last may be speci-
fied as for the index method.
string trim string ?chars?
Returns a value equal to string except that any leading
or trailing characters from the set given by chars are
removed. If chars is not specified then white space is
removed (spaces, tabs, newlines, and carriage returns).
string trimleft string ?chars?
Returns a value equal to string except that any leading
characters from the set given by chars are removed. If
chars is not specified then white space is removed
(spaces, tabs, newlines, and carriage returns).
string trimright string ?chars?
Returns a value equal to string except that any trail-
ing characters from the set given by chars are removed.
If chars is not specified then white space is removed
(spaces, tabs, newlines, and carriage returns).
string wordend string charIndex
Returns the index of the character just after the last
one in the word containing character charIndex of
string. charIndex may be specified as for the index
method. A word is considered to be any contiguous
range of alphanumeric (Unicode letters or decimal
digits) or underscore (Unicode connector punctuation)
characters, or any single character other than these.
string wordstart string charIndex
Returns the index of the first character in the word
containing character charIndex of string. charIndex
may be specified as for the index method. A word is
considered to be any contiguous range of alphanumeric
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Tcl Built-In Commands string(1T)
(Unicode letters or decimal digits) or underscore
(Unicode connector punctuation) characters, or any sin-
gle character other than these.
EXAMPLE
Test if the string in the variable string is a proper non-
empty prefix of the string foobar.
set length [string length $string]
if {$length == 0} {
set isPrefix 0
} else {
set isPrefix [string equal -length $length $string "foobar"]
}
SEE ALSO
expr(1T), list(1T)
KEYWORDS
case conversion, compare, index, match, pattern, string,
word, equal, ctype
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWTcl
Interface Stability Uncommitted
NOTES
Source for Tcl is available on http:/opensolaris.org.
Tcl Last change: 8.1 7
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