regex

Regex,regsub  :

A regular expression is simply a description of a pattern that describes a set of possible characters in an input string.

Example :

	#I want to replace dog with cat in the following statement
	set exp1 "someone let the dog out of bag"
	#First check whether dog is present in bag or not
	set val [regexp (dog) $exp1 sub1 sub2 sub3]
	puts $sub1
	if { $val } {
	regsub dog $exp1 cat exp2
	}
	puts "original expression : $exp1"
	puts "modified expression : $exp2"
	set exp3 "I have one black dog, one white dog and one brown dog in my bag"
	#replace all dogs with corresponding cats
	regsub -all dog $exp3 cat exp4
	puts $exp4
	#When you don't want to include particular pattern in sub-pattern use ?:
	set exp5 "Sasken LSI TI Mirafra"
	regexp "(Sasken|Smartplay).*(?:LSI|Avago).*(Mirafra)" $exp5 sub1 sub2 sub3
	#Output :
	#% puts $sub1
	#Sasken LSI TI Mirafra
	#% puts $sub2
	#Sasken
	#% puts $sub3
	#Mirafra
	set exp6 "Ooh La La Tu Hai Meri Fantasy "
	regexp -nocase (oo)? $exp6 sub1
	puts $sub1
	#If I want to search starting with ^O and ending with y
	regexp "^O.*y$" $exp6
	#Loop through all the words in the exp6 and put the words which doesn't start with vowels
	foreach var $exp6 {
	if { [regexp -nocase {^[^aeiou]} $var ] } {
	puts $var
	}
	}
	#Output
	#La
	#La
	#Tu
	#Hai
	#Meri
	#Fantasy

view raw regex_demo.tcl hosted with ❤ by GitHub