string(n) Tcl Built-In Commands string(n) 







string - Manipulate strings








string option arg ?arg ...?












Performs one of several string operations, depending on
    option. The legal options (which may be abbreviated) are:



  

  
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 Tcl_NumUtfChars manual entry for more details
      on the UTF-8 representation.

  

  
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.

  

  
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.

  

  
Search haystackString for a sequence of characters that exactly
      match the characters in needleString. If found, return the index of
      the first character in the first such match within haystackString.
      If not found, return -1. If startIndex is specified (in any of the
      forms accepted by the index method), then the search is constrained
      to start with the character in haystackString specified by the
      index. For example,








string first a 0a23456789abcdef 5



will return 10, but



string first a 0123456789abcdef 11



will return -1.



  

  
Returns the charIndex'th character of the string argument. A
      charIndex of 0 corresponds to the first character of the string.
      charIndex may be specified as follows:







  

  
For any index value that passes string is integer -strict, the char
      specified at this integral index (e.g. 2 would refer to the
      “c” in “abcd”).

  

  
The last char of the string (e.g. end would refer to the
      “d” in “abcd”).

  

  
The last char of the string minus the specified integer offset N
      (e.g. end-1 would refer to the “c” in
      “abcd”).

  

  
The last char of the string plus the specified integer offset N
      (e.g. end+-1 would refer to the “c” in
      “abcd”).

  

  
The char specified at the integral index that is the sum of integer values
      M and N (e.g. 1+1 would refer to the
      “c” in “abcd”).

  

  
The char specified at the integral index that is the difference of integer
      values M and N (e.g. 2-1 would refer to the
      “b” in “abcd”).




In the specifications above, the integer value M contains
    no trailing whitespace and the integer value N contains no leading
    whitespace.


If charIndex is less than 0 or greater than or equal to the
    length of the string then this command returns an empty 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 an empty string will return 1 on any class. If
      -failindex 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 varname will not be set if the
      function returns 1. The following character classes are recognized (the
      class name can be abbreviated):







  

  
Any Unicode alphabet or digit character.

  

  
Any Unicode alphabet character.

  

  
Any character with a value less than \u0080 (those that are in the 7-bit
      ascii range).

  

  
Any of the forms allowed to Tcl_GetBoolean.

  

  
Any Unicode control character.

  

  
Any Unicode digit character. Note that this includes characters outside of
      the [0-9] range.

  

  
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.

  

  
Any of the forms allowed to Tcl_GetBoolean where the value is
      false.

  

  
Any Unicode printing character, except space.

  

  
Any of the valid string formats for a 32-bit integer value in Tcl, with
      optional surrounding whitespace. In case of under/overflow in the value, 0
      is returned and the varname will contain -1.

  

  
Any proper list structure, with optional surrounding whitespace. In case
      of improper list structure, 0 is returned and the varname will
      contain the index of the “element” where the list parsing
      fails, or -1 if this cannot be determined.

  

  
Any Unicode lower case alphabet character.

  

  
Any Unicode printing character, including space.

  

  
Any Unicode punctuation character.

  

  
Any Unicode space character.

  

  
Any of the forms allowed to Tcl_GetBoolean where the value is
    true.

  

  
Any upper case alphabet character in the Unicode character set.

  

  
Any of the valid forms for a wide integer in Tcl, with optional
      surrounding whitespace. In case of under/overflow in the value, 0 is
      returned and the varname will contain -1.

  

  
Any Unicode word character. That is any alphanumeric character, and any
      Unicode connector punctuation characters (e.g. underscore).

  

  
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.





  

  
Search haystackString for a sequence of characters that exactly
      match the characters in needleString. If found, return the index of
      the first character in the last such match within haystackString.
      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 haystackString at or before the specified
      lastIndex will be considered by the search. For example,








string last a 0a23456789abcdef 15



will return 10, but



string last a 0a23456789abcdef 9



will return 1.



  

  
Returns a decimal string giving the number of characters 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.

  

  
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 previous example is reordered
    like this,




string map {1 0 ab 2 a 3 abc 1} 1abcaababcabababc



it will return the string 02c322c222c.



  

  
See if pattern matches string; return 1 if it does, 0 if it
      does not. If -nocase is specified, then the pattern 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 following
      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 in chars, then any
      character between x and y, inclusive, will match. When used
      with -nocase, the end points of the range are converted to lower
      case first. Whereas {[A-z]} matches “_” when matching
      case-sensitively (since “_” falls between the
      “Z” and “a”), with -nocase this is
      considered like {[A-Za-z]} (and probably what was meant in the first
      place).

  

  
Matches the single character x. This provides a way of avoiding the
      special interpretation of the characters *?[]\ in
    pattern.







  

  
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.

  

  
Returns string repeated count number of times.

  

  
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.

  

  
Returns a string that is the same length as string but with its
      characters in the reverse order.

  

  
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
      specified as for the index method.

  

  
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.

  

  
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
      specified as for the index method.

  

  
Returns a value equal to string except that any leading or trailing
      characters present in the string given by chars are removed. If
      chars is not specified then white space is removed (spaces, tabs,
      newlines, and carriage returns).

  

  
Returns a value equal to string except that any leading characters
      present in the string given by chars are removed. If chars
      is not specified then white space is removed (spaces, tabs, newlines, and
      carriage returns).

  

  
Returns a value equal to string except that any trailing characters
      present in the string given by chars are removed. If chars
      is not specified then white space is removed (spaces, tabs, newlines, and
      carriage returns).

  

  
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.

  

  
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 (Unicode letters or decimal digits) or underscore
      (Unicode connector punctuation) characters, or any single character other
      than these.










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"]
}












expr(n), list(n)










case conversion, compare, index, match, pattern, string, word,
    equal, ctype, character, reverse









  

    8.1
    Tcl