CODEWITHSUNDEEP
stringtcl
user9900698
user9900698

Reputation:

Getting the non-matching part between two strings in TCL

I have two strings in variables where the left part of the string is always same. I need to get the rightmost part:

set cwd "/this/is/my/path"
set full_file "/this/is/my/path/test.tcl"

I need the following:

"/test.tcl"

Upvotes: 1

Views: 483

Answers (2)

glenn jackman
glenn jackman

Reputation: 246754

I can think of two ways:

% set cwd "/this/is/my/path"
% set full_file "/this/is/my/path/test.tcl"

% string map [list $cwd ""] $full_file
/test.tcl

% string range $full_file [string length $cwd] end
/test.tcl

The 2nd one does not verify they are the same though.
And the 1st one does not specify to match at the start of the string.

Both of these caveats can be satisfied with:

if {[string match "${cwd}*" $full_file]} { ... }

Upvotes: 0

Brad Lanam
Brad Lanam

Reputation: 5723

Tcl has excellent path manipulation functions, they may be helpful:

set tail [file tail $full_file]

Note that this will not include the leading /.

If your path may contain other elements past the $cwd, you can use a regular expression to remove the prefix:

regsub $cwd $full_file {} tail
puts $tail

You have to be careful with this, if $cwd contains any special characters that the regular expression recognizes, it will fail or get strange results. In which case you will need a procedure to escape the special characters:

proc escapeRegex { val } {
  regsub -all {([?*.+^${}()\\\[\]"])} $val {\\\1} val
  return $val
}
regsub [escapeRegex $cwd] $full_file {} tail
puts $tail

( This code does not handle leading ~ characters ).

Upvotes: 1

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