Regular expressions in TCL are a way to search text. These help us to find a particular character and then we can use our ways to deal with it. “regexp” represents the regular expression. This helps to match a character in TCL. Below are the few matching expressions.
#1. X -> Exact match.
#2. [a-z] -> Matches lower case letter from a-z.
#3. [A-Z] -> Matches upper case letter from A-Z.
#4. . (dot) -> Any character except newline or space.
#5. ^ -> Beginning of the string
#6. $ -> End of the string.
#7. [0-9] -> Matches the numeric character.
#8. \<special character> -> If looking to match a special character then use backslash.
#9. * -> matches globally
#10. + -> One or more character from search pattern.
#11. ? -> Optional search
#12. \w -> All words
#13. \s -> All backspace
#14. \w {4} -> Will search for only 4 digit word
#15. \w {4,} -> Will search for 4 and more digits.
#16. \w {4,6} -> Will search for words between 4 and 6.
#17. () -> Group of search pattern.
Eg. (t|T) -> t and T, it will search for both.
Syntax: regexp <character_to_be_searched> <search_from> variable_name
Eg.
% regexp i ivlsi var
1
% puts $var
i
% regexp t ivlsi var
0
% regexp -all i "ivlsi vlsi" var
3
% if { [regexp i ivlsi var] == 1} {
puts "$var"
}
I
Written by
Swasti Pujari
Associate Director, Backend Engineering at CoreIC Technologies, with 15+ years in VLSI Physical Design and backend engineering. Previously Practice Head at UST Global, leading Physical Design, STA, EMIR, DFT, and Physical Verification. Delivered 3nm, 6nm and 7nm projects for AMD, Intel, and Microchip, and published IEEE research on hybrid AI-EDA floorplanning.
