The string command
Strings are the basic data items in Tcl. The general syntax of the Tcl?string?command is? ??string?operation stringvalue otherargs
tcl> string?length?abc?
3
tcl> string?index?abc 1
b
tcl> string?range?abcd 1 end
bcd
To compare two strings you can also use?==. But that might not work as you wanted with strings containing digits because 1 equals 1.00 (but not in a string sense).
if? [string?compare?$a $b] {puts "$a and $b differ"}
Use 'first' or 'last' to look for a substring. The return value is the index of the first character of the substring within the string.
tcl> string?first?abc xxxabcxxxabcxx
3
tcl> string?last?abc xxxabcxxxabcxxx
9
tcl> string last abc xxxxxx-1
The 'string match' command uses the glob-style pattern matching like many UNIX shell commands do.?
=====================
Glob-style syntax:
*Matches any number of any character.
?Matches any single character.
[ ]One of a set of characters like [a-z].
======================
tcl> string?match?{a[0-9]bc?def\?ghi*} a5bcYdef?ghixxx
1
tcl> set a [string?tolower?abcXY]
abcxy
tcl> string?toupper?$a
ABCXY
tcl> string?trim?"? abc? "?
abc
tcl> string?trimright?"xxabcxxxx"
xxxabc
tcl> string?trimleft??"? a? bc"?
a? bc
Here comes a small example that finds the word with 'x' in a sentence.
tcl> set s {abc dexfgh ijklm}
tcl> string first x $s?
6
tcl> set start? [string?wordstart?$s 6]? ;# start position
4?
tcl> set? end? ? [string?wordend?$s 6]? ? ;# position after word10?
tcl> string range $s $start? [expr $end - 1]
dexfgh
More commands dealing with strings
tcl> set a abc
tcl>append?a defabcdef
tcl> puts [format"%8s\t%8.4f" $a -12.7]? abcdef? ? ? ? -12.7000
tcl>scan?"distance 12.34m" "%s%f%c" what value unit
3
Regular Expressions
Regular expression syntax
====================
.Matches any character.
*Matches zero or more.
?Matches zero or one.
( )Groups a sub-pattern.
|Alternation.
[ ]Set of characters like [a-z]. [^0-9] means that numbers are excluded.
^Beginning of the string.
$End of string.
============================
tcl>regexp?{hello|Hello} Hello1
tcl> regexp {[hH]ello} Hello1
tcl> regexp {[0-9]\.([a-z])([a-wyz]*)} "xxx8.babcxxxxxx" match s1 s21
tcl> puts "$match $s1 $s2"8.babc b abc
tcl>regsub?{[0-9]\.([a-z])([a-wyz]*)}? "xxx8.babcxxxxxx" {__\1__\2__&__} var; puts $var
xxx__b__abc__8.babc__xxxxxx
Lists
Tcl lists are just strings with a special interpretation. Separated by white space or grouped with braces or quotes.
tcl> set mylist "a b {c d}"?
tcl> set mylist [lista b {c d}]? ? ? ? ;# same as above
tcl>for each?element $mylist {puts $element}
abc d
Here several Tcl commands related to lists:
tcl>lindex?$mylist 1? ? ? ? ;# note the index starts with 0b
tcl>llength?$mylist? ? ? ? ? ;# 'c d' is only one element
3
tcl>lappend?mylist {g h}? ? ;# this time the list name 'mylist' is used
a b {c d} {g h}
tcl>lrange?$mylist 2 end
{c d} {g h}
tcl>linsert?$mylist 3 E x? ? ? ? ? ? ? ;# note that we don't give the list name here!
a b {c d} E x {g h}
tcl> set mylist [linsert $mylist 3 E x]? ;# to change the list we have to use 'set'
a b {c d} E x {g h}
tcl>lsearch?-exact $mylist E? ? ? ? ;# other modes are the default '-glob' and '-regexp'
3
tcl>lreplace?$mylist 3 5 e f {g h i} a b {c d} e f {g h i}
tcl> lreplace $mylist 3 3? ? ? ? ? ? ;# delete element 3
tcl>lsort?"-1.2 -1 -900 -90 1e-3 10"
-1 -1.2 -90 -900 10 1e-3
tcl> lsort -real "-1.2 -1 -900 -90 1e-3 10"? ;# other flags are '-ascii','-integer','-increasing','-decreasing'
-900 -90 -1.2 -1 1e-3 10
tcl> list "a b" c
{a b} c
tcl>concat?"a b" c
a b c
tcl> join "{} usr local bin" /
/usr/local/bin
tcl> split /usr/my-local/bin /-
{} usr my local bin
Arrays
tcl> array?exists?a
0
tcl> set a(0) 0.12;? set a(1) 1.23;? set a(name) hello?
tcl> array?size?a?
3
tcl> array?names?a
0 name 1
tcl> array?get?a
0 0.12 name hello 1 1.23
The initialization could have been done with:
tcl> array?set?a "0 0.12 name hello 1 1.23"
tcl> array set b [array get a]? ? ;# Copy array b from a:
Other array commands are?startsearch,?nextelement,?anymore,?donesearch.
