split - Split a string into a proper Tcl list
split string ?splitChars?
Returns a list created by splitting string at each character that is in the splitChars argument. Each element of the result list will consist of the characters from string that lie between instances of the characters in splitChars. Empty list elements will be generated if string contains adjacent characters in splitChars, or if the first or last character of string is in splitChars. If splitChars is an empty string then each character of string becomes a separate element of the result list. SplitChars defaults to the standard white-space characters.
See also the man page at http://www.tcl.tk/man/tcl/TclCmd/split.htm
Some examples, split comp.unix.misc . split "comp.unix.misc" .
returns "comp unix misc" and
split "Hello world" {}
returns "H e l l o { } w o r l d".
[DKF]: I believe there's a standard (ANSI? POSIX?) somewhere. But the answer
[DKF]: I believe there's a standard (ANSI? POSIX?) somewhere.
But the answer includes "space", "tab", and "newline".
[escargo]: By "tab" do you mean both horizontal tab (ASCII 9) and vertical tab
''[escargo]'' - By "tab" do you mean both horizontal tab (ASCII 9) and
vertical tab (ASCII 11)? (See http://www.asciitable.com/)
Arguments could be made for most of the ASCII characters under 33.
[Strick]: Let's ask Tcl what it thinks are white:
$ env | grep en_
LANG=en_US.UTF-8
$ cat what-chars-does-split-think-are-white.tcl
for {set i 0} {$i<65536} {incr i} {
if {[llength [format "/%c/" $i]] > 1} { puts -nonewline "$i " }
}
$ tclsh what-chars-does-split-think-are-white.tcl
9 10 11 12 13 32 $escargo 2005-04-01 : escargo 4 Jan 2005 - 9 = ASCII TAB, 10 = ASCII LF (line feed), 11 = ASCII VT (vertical tab), 12 = ASCII FF (form feed), 13 = ASCII CR (carriage return), and of course 32 = ASCII Space. 9 = ASCII TAB, 10 = ASCII LF (line feed), 11 = ASCII VT (vertical tab), 12 = I would have thought that the separator characters would count as white space (28-31, FS, GS, RS, US), but I guess they are regarded as "nonprinting" characters. I would have thought that the separator characters would count as white space
Strick: Oops, i forgot to actually use split in my script above. So now I Strick: Oops, i forgot to actually use split in my script above. So now I test four different notions of white, and get three different answers. I understand why Tcl's builtin list-splitting rules must be fixed, regardless of locale. But it seems 'split' should use the list-splitting rule or the the 'string is space' rule, but it uses its own (pre-unicode?) rule: $ cat what-chars-does-split-think-are-white.tcl puts "tcl=info patch LANG=$env(LANG)"
puts -nonewline {according to llength: } puts -nonewline "according to llength: "
if {[llength [format "/%c/" $i]] > 1} { puts -nonewline "$i " }} puts {} puts "" puts -nonewline {according to split: } puts -nonewline "according to split: " for {set i 0} {$i<65536} {incr i} {
if {[llength [split [format "/%c/" $i]]] > 1} { puts -nonewline "$i " }puts {} puts "" puts -nonewline {according to 'string is space': } puts -nonewline "according to 'string is space': " for {set i 0} {$i<65536} {incr i} {
if {[string is space [format "%c" $i]]} { puts -nonewline "$i " }puts {} puts "" puts -nonewline {according to regexp {\s}: } puts -nonewline "according to regexp {\\s}: " for {set i 0} {$i<65536} {incr i} { } puts {} puts "" $ $ tclsh what-chars-does-split-think-are-white.tcl tcl=8.4.7 LANG=en_US.UTF-8 according to llength: 9 10 11 12 13 32 according to split: 9 10 13 32 according to 'string is space': 9 10 11 12 13 32 160 5760 8192 8193 8194 8195 8196 8197 8198 8199 8200 8201 8202 8203 8232 8233 8239 12288 according to regexp {\s}: 9 10 11 12 13 32 160 5760 8192 8193 8194 8195 8196 8197 8198 8199 8200 8201 8202 8203 8232 8233 8239 12288 $
[escargo] 2006-01-27: If split used chars 9 10 11 12 13 32 then there would be
''[escargo] 27 Jan 2006'' - If split used chars 9 10 11 12 13 32 then there would be only two sets, with the smaller set as a proper subset of the larger set.
The two characters that would have to be added are the vertical tab and form feed.
----
Note that the argument named ''splitChars'' above is a series of 0 to n individual characters.
However, if you want to split on a specific sequence of 2 or more characters together,
or if you want to split on a regular expression, split will not work for you.
See [Tcllib]'s [textutil]::[splitx] for that functionality.
[SS] 2004/01/31 - or you can use the following function:
proc wsplit {string sep} {
set first [string first $sep $string]
if {$first == -1} {
return [list $string]
} else {
set l [string length $sep]
set left [string range $string 0 [expr {$first-1}]]
set right [string range $string [expr {$first+$l}] end]
return [concat [list $left] [wsplit $right $sep]]
}
}This version is recursive, so it may be better to rewrite it if you plan to use This version is recursive, so it may be better to rewrite it if you plan to use the function against very long strings with many separators. The difference between wsplit and splitx is that splitx uses regexp, so it may create problems with unknown separators. IL 2005-01-03: on the near anniversary of this proc, the iterative version, IL 2005/01/03 - on the near anniversary of this proc, the iterative version, quick n dirty since I'm in a hurry to parse some html...
proc wsplit { str sepStr } {
set strList {}
set strList [list]
while {[set index [string first $sepStr $str]] != -1} {
while { [set index [string first $sepStr $str]] != "-1" } {
set left [string range $str 0 [expr $index + $sepLength - 1]]
set str [string range $str [expr $index + $sepLength + 1] end]
}
return $strList
}connected to the ones you want
proc wsplit {str sepStr} { proc wsplit { str sepStr } {
if { ![regexp $sepStr $str] } { return $str }
set strList [list]
set pattern "(.*?)$sepStr"
while { [regexp $pattern $str match left] } {
lappend strList $left
regsub $pattern $str "" str
}
lappend strList $str
return $strList
[RS] writes recently:
Note that the wsplit can be done simpler:
2. split on that single char
proc wsplit {str sep} {
split [string map [list $sep \0] $str] \0
}
% wsplit This<>is<>a<>test. <>
This is a test.2006-06-21 Sarnold Here is my version of wsplit: proc wsplit {str sep} {
set out {}
set out ""
if {$sepLen < 2} {
if {$sepLen <2} {
}
while {[set idx [string first $sep $str]] >= 0} {
# the left part : the current element
if {$idx>=0} {
# the left part : the current element
lappend out [string range $str 0 [expr {$idx-1}]]
}
set str [string range $str [incr idx $sepLen] end]
}
# there is no separator anymore, but keep in mind the right part must be
# there is no separator anymore, but keep in mind the right part must be appended}
----
[escargo]: So what should you use when you don't care how many spaces were
So what should you use when you don't care how many spaces were between tokens,
you just want the nonblank tokens in the list and none of the separators?
''-- [escargo]''
[RS]: Easy, just use a filter:
proc filter {cond list} {
set res {}
set res {}
foreach element $list {if [$cond $element] {lappend res $element}}
set res
% filter llength [split "a list with many spaces"]
a list with many spaces... or use
% split regsub -all {[ \t\n+} "a list with many spaces" { }]
... or use % lreplace "a list with many spaces" 0 -1
See Counting characters in a string where split was pretty good...
Kaitzschu mentions, on comp.lang.tcl, this piece of info which is supposedly somewhere in the man pages:
"If splitChars is an empty string then each character of string becomes a separate element of the result list."
Thus,
proc hexdump str {
set l [split {abcdefghijklmnopqrstuvwxyz} {}]results in a list where each character is turned into a separate list entry.
RS 2006-07-04: When you split on "" on a byte array, it may be surprising that the result may contain unscannable characters for \x00 bytes. I had to work around like this:
set res {}
set res {}
foreach c [split $str ""] {
set i [scan $c %c]
if {$i eq ""} {set i 0} ;#<--------------------- here
lappend res [format %02x $i]
}
set res escargo 18 Jun 2007 - (We seem to have some edits getting lost; I'm putting this back in since it seems to have disappeared.) I was realizing that then I was writing a little language that there doesn't seem to be a Tcl command that returns a list made from breaking up a string as the command parser would. split doesn't do it. It made me think how subst has arguments that disable command substitution and variable substitution, while eval does not. There are commands like eval, info complete, string is list that appear to do the tokenization, but the tokenized results are not accessible to the script level. Is there some way (apparently not obvious to me) to get the list form out of the string? PYK 2014-03-02: There was previously a discussion by escargo here that made MG Tcl 8.5's {*} expansion is probably the easiest way. In 8.4 you'd probably need to use eval, which would mean a lot of work to escape special characters, make sure things that the parser would see as one word, such as
[string is int $foo]
become
"[string is int $foo]"
so the eval doesn't split it into separate words, etc. It would be possible, I imagine, but a bit of a pain to do, compared to something like
proc str2list {args} {
return $args
}
set list [str2list {*}$string]in 8.5.
escargo - Reading the original TIP for {expand}, it appears that it was intended to expand a list into separate items for processing. So, using {*} as you did is working around the fact that something is taking $string and tokenizing it, treating the result as a list, and passing it to {*} to expand. Again, it seems, the tokenizing is buried where it is not accessible to a script.
It really seems like there ought to be a way. Right now split doesn't take any control arguments, so that [split -tokens $string] wouldn't break any code.
See also: