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

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NAME

       string - Manipulate strings

SYNOPSIS

       string option arg ?arg ...?
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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 Tcl_NumUtfChars 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 needleString haystackString ?startIndex?
	      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.

       string index string charIndex
	      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:												   |

	      integer																   |
			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").													   |

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

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

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

	      M+N																   |
			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").														   |

	      M-N																   |
			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  white- |
	      space.																   |

	      If charIndex is less than 0 or greater than or equal to the length of the string then this command returns an empty string.	   |

       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 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):

	      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 Tcl_GetBoolean.

	      control	  Any Unicode control character.

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

	      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 Tcl_GetBoolean where the value is false.

	      graph	  Any Unicode printing character, except space.

	      integer	  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.

	      list	  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.

	      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 Tcl_GetBoolean where the value is true.

	      upper	  Any upper case alphabet character in the Unicode character set.							   |

	      wideinteger															   |
			  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.

	      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 needleString haystackString ?lastIndex?
	      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.

       string length string
	      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.

       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  speci-
	      fied,  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.

       string match ?-nocase? pattern string
	      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).

	      x	Matches  the  single  character  x.  This provides a way of avoiding the special interpretation 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  charac-
	      ter  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 charac-
	      ter 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 reverse string															   |
	      Returns a string that is the same length as string but with its characters in the reverse order.

       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 speci-
	      fied,  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 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 speci-
	      fied, 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 trim string ?chars?
	      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).

       string trimleft string ?chars?
	      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).

       string trimright string ?chars?
	      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).

       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 dig-
	      its) 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 (Unicode letters or decimal digits) or underscore
	      (Unicode connector punctuation) characters, or any single 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(n), list(n)

KEYWORDS

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

Tcl									8.1								 string(n)