TclTk Tutorial Dongsoo S Kim dskimiupui edu What

Tcl/Tk Tutorial Dongsoo S. Kim dskim@iupui. edu

What is Tcl/Tk? �Tcl: • • Tool Command Language Interpreted programming (scripting) language Build on-the-fly commands and procedures Embeddable Platform-independent �Tk: • GUI toolkit and widgets based on Tcl • Open source, cross-platform 2

Why Tcl/TK? � Easy and fast programming � Free � Lots of online documentation, mostly free �Resources • http: //www. tcl. tk �Major applications use the Tcl as their interfaces: • Ns 2 • Mentor Graphics 3

Hello World > tcl % puts "Hello. World!" Hello. World! % exit > 115. 145. 171. 157 4

Script File �Start the Tcl program followed by a filename containing the script. > cat hello. tcl puts "Hello. World!" > tcl hello. tcl Hello. World! > 5

Script as a Program � A script text file can be considered as a program • it is an executable file, and • its first line contains a full path name of the tcl program if following “#!” > ls -l -rwxr-xr-x 1 user group 42 Jul 3 13: 12 hello. tcl > which tcl /usr/local/bin/tcl > cat hello. tcl #!/usr/local/bin/tcl puts "Hello. World!" > hello. tcl Hello. World! > 6

Tcl Syntax �Simple syntax • command_name arg 1 arg 2 … � Print to screen (puts) % puts –nonewline "Hello. " % puts "World!" � Assignment (set) % set income 32000 % puts "The income is $income" • Use '$' to get the value of a variable (R-value) 7

Comments �A line started with a pond sign(#) is ignored as comments until the end of the line � A command can be followed by a comment in a line with by placing ; # � Exception • #! at the first line indicates the script program • It is a Unix rule, but not a Tcl rule # the first script puts –nonewline "Hello. " puts "World!“ ; # continuing 8

Multiple Commands in a Line �A Tcl command is terminated by an invisible new line character, or �A semicolon(; ) can be used to explicitly terminate a command % puts "Hello. "; puts "World! " hello world 9

A Command Stretched to Lines �A command can be stretched to multiple lines by using backslashes () �The backslash and a following new line character is ignored �Note: There must not be any characters (even space characters) between the backslash and the new line character % puts -nonewline =>"Hello. World!" Hello. World!tcl> 10

Mathematical Expression � Mathematical expression command (expr) � Operators • arithmetic (+, -, *, /, %) • Bitwise (~, <<, >>, &, ^, |) • Logical (!, &&, ||) • Boolean (<, >, <=, >=, ==, !=) • String Boolean (eq, ne, <, >, <=, >=) • List containment (in, ni) • Ternary (x? y: z) % set pi 3. 141592 • Math functions (log, sin, cos, …) % set r 2 % expr 2*$pi*$r 12. 566368 % expr sin($pi/3) 0. 866025294853 11

Sub-Command Evaluation �A Tcl command in a Tcl command: [] % set a 3. 0 % set b $a+4 % puts $b 3. 0+4 % set c [expr $a+4] % puts $c 7. 0 12

Control Structures (if) � if {cond} {commands} [ elseif {cond} {commands} …] [ else {commands} ] set sel 3 if {$sel puts } elseif puts } else { puts } == 1} { "Selection $sel" {$sel == 2} { "Selection $sel" "Invalid selection" 13

Control Structures (while) � while {cond} {commands} set i 1 set sum 0 while {$i <= 10} { set sum [expr $sum+$i] incr i } 14

Control Structures (for) � for {init} {term} {incr} {statements} puts "Fahrenheitt. Celcius" for {set fahr 0} {$fahr < 100} {incr fahr} { set celc [expr 5*($fahr-32)/9] puts "$fahrtt$celc" } Fahrenheit 0 1 2 … Celcius -18 -17 15

Control Structures (foreach) � Basic foreach set weekdays {Sun Mon Tue Wed Thu Fri Sat} foreach d $weekdays { puts $d } � foreach Variations set Colors {red orange yellow green blue purple} foreach {a b c} $Colors { puts "$c--$b--$a“ } set Foods {apple orange banana lime berry grape} foreach f $Foods c $Colors { puts "a $f is usually $c" } foreach {a b} $Foods c $Colors { puts "$a & $b are foods. $c is a color. " } 16

Procedures � Called by value only �Syntax proc name arg-list proc-body proc mile 2 km dist { return [expr $dist*1. 6] } puts "Miles t KM" for {set d 1} {$d < 10} {incr d} { set km [mile 2 km $d] puts "$dt $km" } 17

Variable scope � By default, all variables in a procedure are local. � To access the variable outside of the scope, useset theacommand “global”. 5 set b 6 set c 7 proc var_scope { } { global a set a 3 set b 2 set : : c 1 } var_scope puts "The value for a b c is: $a $b $c" 18

Lists in Tcl An ordered collection of elements A string containing any number of elements separated by white spaces (space or tab characters). For example, Sun Mon Tue Wed Thu Fri Sat is a list with seven elements. � To save a list to a variable � � set my_list [list a b c] set my_list "a b c " set my_list {a b c} 19

List Operations concat – join multiple list into a single list join – concatenate list elements into a string lappend – append elements to an existing list lindex – return an indexed element from a list linsert – insert an element to an existing list – create explicitly a list from values llength – return the number of elements in a list lrange – return a sub-list from a list lreplace – return a new list after replacing elements � lsearch – return the index of a searching pattern � lsort – sort the list � split – return a list by splitting a string by a splitchar. � � � � � 20

List Operations, Example set weekday [list “Mon” “Tue” “Wed” “Thu” “Fri”] set weekend {Sat Sun} set week [concat $weekday $weekend] puts $week ÞMon Tue Wed Thu Fri Sat Sun lindex $week 0 ÞMon lindex $week end ÞSun llength $weekday Þ 5 21

Lists of lists (of lists…) set a [list x y z]] puts [lindex $a 0] 1] puts [lindex $a 1] 0] (unexpected result) set a [list x [list y] [list z]]] => How to get to the z? set arg 1 [list g [list f [list h [list i X]]] [list r Y] k] set arg 2 [list g [list f [list h [list i Y]]] [list r b] L] set both [list $arg 1 $arg 2] puts $both 23

Array operations Associative arrays (string as index) set color(rose) red set color(sky) blue set color(medal) gold set color(leaves) green set color(blackboard) black puts [array exists color] (tests if an array with the name "color" exists) puts [array exists colour] puts [array names color] (returns a list of the index strings) foreach item [array names color] { puts "$item is $color($item)" } (iterating through array) set lst. Color [array get color] (convert array to list) array set color $lst. Color (convert list to array) 24

Regular expressions � regsub set stmt "Fan is one of Shania’s fans" regsub –nocase "fan" $stmt "Kristy" new. Stmt ? switches? exp string sub. Spec ? var. Name? puts "$new. Stmt" regsub –nocase –all "fan" $stmt "Kristy" new. Stmt puts "$new. Stmt" � regexp (returns 1 if the regular expression matches the string, else returns 0) puts [regexp –nocase "fan" $stmt] ? switches? regexp string � format puts [format "%s is a %d-year-old" Fan 26] format. String ? arg. . . ? 25

String operations set statement " Fan is a student " set statement [string trim $statement] puts [string length statement] puts [string index $statement 4] puts [string index $statement end] puts [string first "is" $statement] (string last) puts [string first $statement "is"] puts [string range $statement 4 end] puts [string replace $statement 9 end "professor"] puts [string match "*student" $statement] (* ? []) 26

File Operations set f. Read [open source. txt r] set f. Write [open target. txt w] while {![eof $f. Read]} { set str. Line [gets $f. Read] ; #or gets $f. Read str. Line regsub –nocase –all "fan" $str. Line "kristy" str. Line puts $f. Write $str. Line } close $f. Read close $f. Write ######## source. txt ######## Fan is a CSE student. Fan is also one of Shania’s fans. Kristy and Fan are classmates. 27

Miscellaneous commands � eval: execute a command dynamically built up in your program set Script { set Number 1 17 set Number 2 25 set Result [expr $Number 1 + $Number 2] } eval $Script � � � exec: execute external programs clock trace info after 28