This looks as expected:
set a 1
puts [string match $a $a]
>> 1
However I find this unexpected:
set b {[1]}
puts [string match $b $b]
>> 0
Can you help explain the above behaviour?
The pattern [1] is a bracket expression that matches the characters inside the brackets. In this case, the only string that will match the pattern is 1.
% set b {[1]}
[1]
% puts [string match $b $b]
0
% puts [string match $b "1"]
1
%
If you'd like to compare two strings to see if they are identical, use string equal ... instead.
If you are in a unix shell environment, man n string or man 3tcl string should bring up a manual page with details about the string command.
Related
Input string : 4567-ABC
I want to remove everything before "-" in the string so that Output will be ABC.
Output: ABC
If you want to avoid regular expressions:
set string 4567-ABC
set output [lindex [split $string "-"] 1]
The split command takes a string and split characters as the arguments and returns a list.
string last is useful here:
set string 4567-ABC
set idx [string last "-" $string]
set wanted [string range $string $idx+1 end]
Or without the intermediate variable
set wanted [string range $string [string last "-" $string]+1 end]
That even works if the original string does not contain any hyphens.
How to escape special characters(e.g "[]") while using search?
Consider the following scenario:
>> set L { a b c [] }
>> a b c []
>> lsearch $L b
>> 1
>> lsearch $L "[]"
>> -1
I'm looking to get 3 when I run lsearch $L "[]"
When looking for fixed strings rather than patterns, it is easiest to use the -exact option to lsearch. You also need to make sure Tcl doesn't do substitution on the search string, for example by enclosing it inside curly braces. Otherwise you'll tell Tcl to look for an empty string (the result of executing an empty command string):
lsearch -exact $L {[]}
I have a question regarding possibility of getting string after specific character in TCL.
Whan I mean is :
Input:
abcdefgh = hgfedcba
Output:
hgfedcba
(return everything after "=" without possible whitespaces)
This is what I was using:
regexp {abcdefgh=\s+"(.*)"} $text_var all variable
In some cases it is ok (with spaces) but when there is no whitespaces then it is not working.
Assuming
% set s {abcdefgh = hgfedcba}
# => abcdefgh = hgfedcba
(or the same thing without one or both of the blanks) you could do one of these:
% scan $s {%*[^=]= %s}
# => hgfedcba
(Scan the string for a substring not containing "=", then advance past the equals sign and optional whitespace, then return the rest of the string.)
string trim [lindex [split $s =] 1]
(Split the string at the equals sign, return the (whitespace-trimmed) second resulting element.)
string trim [string range $s [string first = $s]+1 end]
(Return the (whitespace-trimmed) substring starting after the equals sign.)
string trim [lindex [regexp -inline {[^=]+$} $s] 0]
(Return the (whitespace-trimmed) first match of one or more characters, not including the equals sign, anchored on the end of the string.)
lindex [regexp -inline -all {[a-h]+} $s] 1
(Return the second match of consecutive characters from the set "a" to "h".)
string trimleft [string trimleft $s {abcdefgh }] {= }
(Remove all characters from the start of the string that occur in the set "a" to "h" and blank, then remove from start of the resulting string any characters that are equals sign or blank.)
% regexp {abcdefgh\s*=\s*(\S+)} "abcdefgh = hgfedcba" all variable
1
% set variable
hgfedcba
% regexp {abcdefgh\s*=\s*(\S+)} "abcdefgh=hgfedcba" all variable
1
% set variable
hgfedcba
%
I have this string:
svpts-7-40.0001
And I need to remove the second '-' from this.
Basically I am fetching values like these which would come with double '-' SOMETIMES. So if such variables are seen then I have to remove the second '-' and replace the same with '.' , so the string should look like:
svpts-7.40.0001
[EDIT] I have tried:
% set list1 [split $string -]
svpts 7 40.0001
% set var2 [join $list1 .]
svpts.7.40.0001
%
Here's a regular expression that will change only the 2nd hyphen:
% regsub -expanded {( .*? - .*? ) -} "svpts-7-40.0001" {\1.}
svpts-7.40.0001
% regsub -expanded {( .*? - .*? ) -} "svpts-7_40.0001" {\1.}
svpts-7_40.0001
% regsub -expanded {( .*? - .*? ) -} "svpts-7-40.0001-a-b-c" {\1.}
svpts-7.40.0001-a-b-c
Try
% set data svpts-7-40.0001
svpts-7-40.0001
% regexp {([^-]*-)(.*)} $data -> a b
1
% set b [string map {- .} $b]
7.40.0001
% set newdata $a$b
svpts-7.40.0001
The above code changes every hyphen after the first. To change only the second hyphen, one can do this:
set idx [string first - $data [string first - $data]+1]
set newdata [string replace $data $idx $idx .]
or this:
set idxs [lindex [regexp -inline -all -indices -- - $data] 1]
set newdata [string replace $data {*}$idxs .]
The first snippet is well-behaved if the data string doesn't contain at least two hyphens; the other needs some kind of checking to avoid throwing an error.
Documentation:
lindex,
regexp,
set,
string,
{*} (syntax),
Syntax of Tcl regular expressions
Syntax of Tcl index expressions:
integer zero-based index number
end the last element
end-N the nth element before the last element
end+N the nth element after the last element (in practice, N should be negative)
M-N the nth element before element m
M+N the nth element after element m
There can be no whitespace within the expression.
I am new to TCL, just wanted to know that how can we search for "," in a string and want the particular string before and after.
Example : tampa,florida
It has to search for , if in that string if there is , it should return tampa and florida we can use string replace but it will not work in my condition because i need to map, tampa and florida to different set of variables dont even know how the inbound would look like to use string range.
.
Thanks,
Arya
Unless there is some further condition, you could do it this way:
split tampa,florida ,
This command gives as result a list containing the two strings "tampa" and "florida".
Documentation: split
The shortest piece of code to do this would be using regular expressions:
if {[regexp {(.+),(.+)} $string a b c]} {
# $a is the complete match. But we don't care
# about that so we ignore it
puts $b; #tampa
puts $c; #florida
}
The regular expression (.+),(.+) means:
(
. any character
+ one or more of the above
) save it in a capture group
, comma character
(
. any character
+ one or more of the above
) save it in a capture group
See the documentation of regular expression syntax in tcl for more about regular expressions: https://www.tcl.tk/man/tcl8.6/TclCmd/re_syntax.htm
But if you're not familiar with regular expressions and want an alternative way of doing this you can use the various string commands. This is one way to do it:
set comma_location [string first "," $string]
if {$comma_location > -1} {
set a [string range $string 0 [expr {$comma_location -1}]
set b [string range $string [expr {$comma_location +1}] end]
puts $a; #tampa
puts $b; #florida
}
A variant of slebetman's last answer.
proc before_after {value find {start 0}} {
set index [string first $find $value $start]
set left_side [string range $value $start [expr $index - 1]]
set right_side [string range $value [expr $index + 1] end]
return [list $left_side $right_side]
}
puts [before_after "tampa,fl" ","]
output:
tampa fl