lists

• Lists
• Lists are equivalent to arrays in the conventional programming language like C.
• Lists can be expanded and collapsed on the fly.

• Example 1:
• set list1 "a  b c d"

• Functions associated with lists :
• lindex
• lappend
• lindex
• llength
• lrange
• lreplace
• lsearch
• lsort
• split
• join
• concat

Example 2:

	#Initialize a list
	set list1 "a b c d"
	puts $list1
	#Now add words "hello", "world" to above list
	lappend list1 hello
	puts $list1
	lappend list1 world
	puts $list1
	#When we use lappend to append any string it will be added at the last
	#Now list1 has the value "a b c d hello world"
	#If we want to refer the string in the 3rd place, Lists index will start from 0 so we need to refer with index=2
	puts [lindex $list1 2]; #output will be "c"
	#Lets say I want to insert x y z after c, i.e. before the index=2.
	#*** IMPORTANT NOTE:
	#It will not modify the original list. We need to overwrite the original list by assigning to return value.
	set list1 [linsert $list1 2 x y z]
	puts $list1
	#Lets say I want to replace "c d" with "s t u v". Even lreplace will not modify the original list.
	# value of list1 is
	#a b x y z c d hello world
	set list1 [lreplace $list1 5 6 s t u v] ; #Now the value of list has been updated to "a b x y z s t u v hello world"
	puts $list1
	#Lets say I want the slice in the list from s to v, it will not modify the original list
	puts [lrange $list 5 end-2]
	#concat
	set list2 "tcl session is very boring"
	set mergedlist [concat $list1 $list2]
	puts $mergedlist
	#llength
	puts [llength $mergedlist]
	#you might want to replace/trim certain characters in the list
	#split
	#lets say I am reading a csv file, I want to postprocess the data in the csv file or if I want to print in the readable format.
	set list3 "a,b,c,d"
	set list4 [split $list3 ,]
	#join the words with colon
	set list5 [join $list4 :]
	#lsearch operations:
	set a {Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec}
	lsearch -exact $a jun; # output -1
	lsearch -exact $a Jun; # output 5
	lsearch -glob $a J* ; #output 0
	lsearch -glob $a J. ; #output -1
	lsearch -glob $a J?? ; #output 0
	lsearch -regexp $a {[A-Z]e[a-z]} #output 1, if you don't give curly brace it will issue a syntax error stating invalid command.

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