Search backslach in tcl using regexp

Question

How to search backslash "\" in tcl using regexp. I tried following

regexp {\\} "b\a"
regexp {\\\\} "b\a"

I want to search text between "." and "\.". How to do this? Eg: abcd.efg\.hij => efg , for this I tried this:

regexp {\.[a-z]*\\.} "abcd.efg\.hij" X

Answer 1

When single backslash is used in double quotes, then it has no special meaning at all. It should be escaped.

% set input "abcd.efg\.hij"; # Check the return value, it does not have backslash in it
abcd.efg.hij
%
% set user "din\esh"; # Check the return value
dinesh
%
% set input "abcd.efg\\.hij"; # Escaped the backslash. Check the return value
abcd.efg\.hij
%
% set input {abcd.efg\.hij}; # Or you have to brace the string
abcd.efg\.hij
%

So, your regexp should be updated as ,

% regexp "\\\\" "b\\a"
1
% regexp {\\} "b\\a"
1
% regexp {\\} {b\a}
1
% regexp {\\} {b\\a}
1
%

To extract the required data,

% set input {abcd.efg\.hij}
abcd.efg\.hij
%  regexp {\.(.*)?\\} $input ignore match
1
% set match
efg