<> if 0 { ---- **Introduction** [MiHa] 2015-06-13: HelloWorld-programs are supposed to be the most simple, working programs of a given language. But I want to extend such a HelloWorld-program to a one-page - reference-card, <
> where all the essential features of the language are shown. <
> Several short programs would be ok, too. <
> If possible, while doing something useful (and/or funny). Tcl by itself (without Tk) is http://wiki.tcl.tk/10259%|%quite simple%|%, so an amount of code to fill about one printed page should be enough. <
> (The layout may need to be tweaked, e.g. printing front and back, landscape, and in 2-4 columns:) Basic [Tcl Commands] to cover: * http://wiki.tcl.tk/1669%|%Comments%|% / statements * Output: [puts] / -nonewline ** [format] * Numeric [variable]s: [set] * multiple statements / assignments in one line ** simple calculations: [incr] / [expr] * [proc] / [return] - for functions * basic flowcontrol: ** [if] / then / else / elseif / comparing ** [for] - loop, maybe also the [while]-loop / [break] / [continue] * [foreach] * String variables / quoting * [catch] * [exit] Advanced features (to include if space permits): * input: [gets], [eof], [scan] / checking the input <
>This is an important topic, but likely too much for one page. * [global] / $::var * [upvar] / http://wiki.tcl.tk/1508%|%Using upvar with an array%|% * [string]-operations (e.g. find/extract/replace char in a string, append, delete/split ...) * [data structure]s: ** [list] / [lassign], [lappend], [lset], [linsert], [lreplace] / [lindex], [llength] / [lrange], [lsearch], [lsort] ** [array] / [parray] ** [dict] * [file]-operations / [open], [close] / [glob] * [proc] with a variable number of arguments / default values / args ... More features, to be left out, for a later lesson (too advanced, or too rarely needed for an introduction): * [package]s and [namespace]s * [eval] * [interp] * [lambda] * [regexp] - this is very likely too complex to cover as just one small example on a general introduction page. * [switch] * [unknown] * [uplevel] ... Things to be aware of: * comments are commands, so quotes and braces inside need to be balanced <
>see [Why can I not place unmatched braces in Tcl comments] * when to use / not to use "$" with variablenames ( set i 1; puts $i; incr i $i ) Maybe there already are some programs here in the wiki that would qualify for such a refcard-program... } ---- **Program 1 - puts** ======tcl # HelloWorld001.tcl - 2015-06-13 - http://wiki.tcl.tk/41268 # Output a string to terminal: puts "Hello, World!" ### END ### ====== ---- **Program 2 - set, incr, catch, if, exit** ======tcl # HelloWorld002 - 2015-06-25 # http://ideone.com/ZWCbmF # Assign value to variables, and output: set a "The answer is" ;# assign a constant text set x 42 ;# assign a constant number set n $x ;# assign contents of a variable puts $a puts $x puts "n = $n" incr n ;# add 1 to a numeric variable incr n 2 ;# add 2 to a numeric variable catch { incr a } ;# try a command, catch and ignore errors if { [ catch {incr a} ] } { ;# catch error, and do something: puts "!! Cannot increment variable containing a string: '$a' !!" #exit 1 ;# exit program with an errorcode } puts "$a now $n" # END # ====== '''Output 2''' ======none The answer is 42 n = 42 !! Cannot increment variable containing a string: 'The answer is' !! The answer is now 45 ====== ---- **Program 3 - clock, timedate, if, else** ======tcl # HelloWorld003.tcl - MiHa - 2015-06-13 # http://wiki.tcl.tk/41268 / http://ideone.com/xl0IBI # Query the time (cs as a number, td and hh as a string), # output depending on the value of the hour: set cs [clock seconds] ;# seconds since 1970-01-01 set td [clock format $cs -format "%Y-%m-%d %H:%M:%S" ] ;# timedate set hh [clock format $cs -format %H ] ;# hours (00-23) puts "cs=$cs td='$td' hh=$hh" if { $hh < "12" } { puts -nonewline "Good morning, " } else { puts -nonewline "Hello, " } puts "World!" # END # ====== '''Output 3''' ======none cs=1434926575 td='2015-06-21 22:42:55' hh=22 Hello, World! ====== ---- **Program 4 - clock, if,else,elseif** ======tcl # HelloWorld004.tcl - MiHa - 2015-06-21 # http://wiki.tcl.tk/41268 / http://ideone.com/Llp8Os # Query the hour from the clock, # output text depending on the value of the hour: set cs [clock seconds] ;# seconds since 1970-01-01 set hh [clock format $cs -format %H ] ;# hours (00-23) puts "cs=$cs hh=$hh" if { $hh < "12" } { puts -nonewline "Good morning, " } elseif { $hh > "18" } { puts -nonewline "Good evening, " } else { puts -nonewline "Hello, " } puts "World!" # END # ====== '''Output 4''' ======none cs=973531773 hh=17 Hello, World! ====== and ======none cs=1434927642 hh=23 Good evening, World! ====== ---- **Program 5 - string compare** ======tcl # HelloWorld005 - 2015-06-23 # http://ideone.com/OJoort # Comparing strings: set hh "20" set tx "Hello" if { $hh < "12" } { set tx "Good Morning" } if { $hh > "18" } { set tx "Good Evening" } puts "It is $hh:00 --> $tx, World !" #. ====== '''Output 5''' ======none It is 20:00 --> Good Evening, World ! ====== ---- **Program 6 - proc,return** ======tcl # HelloWorld006 - 2015-06-23 # http://ideone.com/GBiMab # Comparing strings, proc as function proc greeting {hh} { set gr "Hello" if { $hh < "12" } { set gr "Good Morning" } if { $hh == "12" } { set gr "Happy Lunchtime" } if { $hh > "18" } { set gr "Good Evening" } return $gr } set hh "12" set tx [greeting $hh] puts "It is $hh:00 --> $tx, World !" #. ====== '''Output 6''' ======none It is 12:00 --> Happy Lunchtime, World ! ====== ---- **Program 7 - proc, while, gets** ======tcl # HelloWorld007 - 2015-06-23 # http://ideone.com/mcV6YL # Comparing strings, proc as function, input in while-loop proc greeting {hh} { # This proc returns a result as soon as a match is found: set gr "Hello" if { $hh < "12" } { return "Good Morning" } if { $hh == "12" } { return "Happy Lunchtime" } if { $hh > "24" } { return "Goodbye" } if { $hh > "18" } { return "Good Evening" } return $gr } set hour "99" ;# start with any value that keeps the loop going while { $hour > "0" } { puts -nonewline "Enter hour, 0 to quit: " set hour [gets stdin] puts $hour puts "It is $hour:00 --> [greeting $hour], World !" } puts "Bye!" #. ====== '''Output 7''' ======none Enter hour, 0 to quit: 1 It is 1:00 --> Good Morning, World ! Enter hour, 0 to quit: 11 It is 11:00 --> Good Morning, World ! Enter hour, 0 to quit: 12 It is 12:00 --> Happy Lunchtime, World ! Enter hour, 0 to quit: 15 It is 15:00 --> Hello, World ! Enter hour, 0 to quit: 17 It is 17:00 --> Hello, World ! Enter hour, 0 to quit: 18 It is 18:00 --> Hello, World ! Enter hour, 0 to quit: 19 It is 19:00 --> Good Evening, World ! Enter hour, 0 to quit: 25 It is 25:00 --> Goodbye, World ! Enter hour, 0 to quit: 0 It is 0:00 --> Good Morning, World ! Bye! ====== ---- **Program 8 - for with integer, format** ======tcl # HelloWorld008 - 2015-06-23 # http://ideone.com/lKo08L # Comparing strings, proc as function, for-loop, format proc greeting {hh} { # This proc returns a result as soon as a match is found: set gr "Hello" if { $hh < "12" } { return "Good Morning" } if { $hh == "12" } { return "Happy Lunchtime" } if { $hh > "24" } { return "Goodbye" } if { $hh > "18" } { return "Good Evening" } return $gr } puts "Greeting:" for {set h 0} {$h<=25} {incr h} { #set hour $h ;# Tcl converts number to string, as needed #set hour [format "%2d" $h] ;# format as numeric string with 2 digits set hour [format "%02d" $h] ;# format as 2 digits with leading 0 puts "at $hour:00 --> [greeting $hour], World !" } puts "Done." #. ====== '''Output 8''' ======none Greeting: at 00:00 --> Good Morning, World ! at 01:00 --> Good Morning, World ! at 02:00 --> Good Morning, World ! at 03:00 --> Good Morning, World ! at 04:00 --> Good Morning, World ! at 05:00 --> Good Morning, World ! at 06:00 --> Good Morning, World ! at 07:00 --> Good Morning, World ! at 08:00 --> Good Morning, World ! at 09:00 --> Good Morning, World ! at 10:00 --> Good Morning, World ! at 11:00 --> Good Morning, World ! at 12:00 --> Happy Lunchtime, World ! at 13:00 --> Hello, World ! at 14:00 --> Hello, World ! at 15:00 --> Hello, World ! at 16:00 --> Hello, World ! at 17:00 --> Hello, World ! at 18:00 --> Hello, World ! at 19:00 --> Good Evening, World ! at 20:00 --> Good Evening, World ! at 21:00 --> Good Evening, World ! at 22:00 --> Good Evening, World ! at 23:00 --> Good Evening, World ! at 24:00 --> Good Evening, World ! at 25:00 --> Goodbye, World ! Done. ====== ---- **Program 9 - expr, format** ======tcl # HelloWorld009.tcl - 2015-06-23 # http://ideone.com/kgfFX1 # calculations using expr, formatting numbers set x 3.0 set y 7.0 set distance [expr sqrt($x * $x + $y * $y)] set dist2 [format %9.2f $distance] ;# format as float with 2 decimal digits puts "x=$x y=$y distance=$distance ==> $dist2" #. ====== '''Output 9''' ======none x=3.0 y=7.0 distance=7.615773105863909 ==> 7.62 ====== ---- **Program 10 - proc, expr, format, for with float, output as table** ======tcl # HelloWorld010.tcl - 2015-06-23 # http://ideone.com/Pjrz4x # calculations using expr, formatting numbers/strings as table proc distance {x y} { # calculate, return result as number return [expr sqrt($x * $x + $y * $y)] } proc ff {num} { # format number as float with 4 decimal digits set f [format %9.4f $num] return $f } proc fs {tx} { # format text with fixed width, for use as header return [format %9s $tx] } proc showDistance {x y} { # calculate, format numbers, output / return nothing set distance [format %9.4f [expr sqrt($x * $x + $y * $y)]] puts "x=[ff $x] y=[ff $y] distance=$distance" } showDistance 1.0 1.0 set x 2.0; set y 5.0; showDistance $x $y set x 5.0; set y 12.0; showDistance $x $y puts "\nTable:" ;# newline puts "[fs x] [fs y] [fs distance]" puts "[fs =] [fs =] [fs ========]" for {set x 0.0} {$x<=11.0} {set x [expr $x+2.5]} { for {set y 11.5} {$y<13.0} {set y [expr $y+0.5]} { #puts "$x $y" puts "[ff $x] [ff $y ] [ff [distance $x $y ] ]" } puts "" } puts "Done." #. ====== '''Output 10''' ======none x= 1.0000 y= 1.0000 distance= 1.4142 x= 2.0000 y= 5.0000 distance= 5.3852 x= 5.0000 y= 12.0000 distance= 13.0000 Table: x y distance = = ======== 0.0000 11.5000 11.5000 0.0000 12.0000 12.0000 0.0000 12.5000 12.5000 2.5000 11.5000 11.7686 2.5000 12.0000 12.2577 2.5000 12.5000 12.7475 5.0000 11.5000 12.5399 5.0000 12.0000 13.0000 5.0000 12.5000 13.4629 7.5000 11.5000 13.7295 7.5000 12.0000 14.1510 7.5000 12.5000 14.5774 10.0000 11.5000 15.2398 10.0000 12.0000 15.6205 10.0000 12.5000 16.0078 Done. ====== ---- **Program 11 - foreach, for, list,lappend,llength,lindex** ======tcl # HelloWorld011.tcl - 2015-06-24 # http://ideone.com/Ia463h # foreach, list,lappend,llength,lindex: set deck {} ;# create empty list puts "Deck of cards:" foreach rank { A 2 3 4 5 6 7 8 9 10 J Q K } { ;# Ace 2 .. 10 Jack Queen King foreach suit { S H D C } { ;# Spades Hearts Diamonds Clubs set card "$rank$suit" puts -nonewline " $rank-$suit:$card " lappend deck $card ;# add card to deck } puts "" } puts "\nThe list with the deck of cards has [llength $deck] elements:" for {set i 0; set n 0} {$i < [llength $deck]} {incr i; incr n} { if { $n >= 8 } { puts ""; set n 0 } ;# newline after 8 cards if { $n == 4 } { puts -nonewline " " } ;# extra space after 4 cards set c [lindex $deck $i] ;# get element #i from the list puts -nonewline "$i: $c " } puts "\nDone." #. ====== '''Output 11''' ======none Deck of cards: A-S:AS A-H:AH A-D:AD A-C:AC 2-S:2S 2-H:2H 2-D:2D 2-C:2C 3-S:3S 3-H:3H 3-D:3D 3-C:3C 4-S:4S 4-H:4H 4-D:4D 4-C:4C 5-S:5S 5-H:5H 5-D:5D 5-C:5C 6-S:6S 6-H:6H 6-D:6D 6-C:6C 7-S:7S 7-H:7H 7-D:7D 7-C:7C 8-S:8S 8-H:8H 8-D:8D 8-C:8C 9-S:9S 9-H:9H 9-D:9D 9-C:9C 10-S:10S 10-H:10H 10-D:10D 10-C:10C J-S:JS J-H:JH J-D:JD J-C:JC Q-S:QS Q-H:QH Q-D:QD Q-C:QC K-S:KS K-H:KH K-D:KD K-C:KC The list with the deck of cards has 52 elements: 0: AS 1: AH 2: AD 3: AC 4: 2S 5: 2H 6: 2D 7: 2C 8: 3S 9: 3H 10: 3D 11: 3C 12: 4S 13: 4H 14: 4D 15: 4C 16: 5S 17: 5H 18: 5D 19: 5C 20: 6S 21: 6H 22: 6D 23: 6C 24: 7S 25: 7H 26: 7D 27: 7C 28: 8S 29: 8H 30: 8D 31: 8C 32: 9S 33: 9H 34: 9D 35: 9C 36: 10S 37: 10H 38: 10D 39: 10C 40: JS 41: JH 42: JD 43: JC 44: QS 45: QH 46: QD 47: QC 48: KS 49: KH 50: KD 51: KC Done. ====== ---- **Program 12 - foreach 2, unicode-chars, string,append, lappend, array,parray** ======tcl # HelloWorld012.tcl - 2015-06-24 # http://ideone.com/uKSgZR # foreach, unicode-chars, append, lappend, array,parray set deckStr "" ;# create empty string set deckList {} ;# create empty list array set deckArray {} ;# create empty array puts "Deck of cards:" set i 0 # see also: http://wiki.tcl.tk/26403 : [HTML character entity references] # Spades Hearts Diamonds Clubs foreach {suit sym} { S \u2660 H \u2665 D \u2666 C \u2663 } { foreach rank { A 2 3 4 5 6 7 8 9 10 J Q K } { ;# Ace 2 .. 10 Jack Queen King incr i set card "$rank$sym" puts -nonewline " $rank$suit=$card " append deckStr $card ;# add card to string lappend deckList $card ;# add card to list set deckArray($i) $card ;# add card to array } puts "" } set maxCard $i puts "\ndeckStr : $deckStr" ;# note: no spaces between puts "S) card #3 : [string range $deckStr 4 5]" ;# 0-1 2-3 4-5 ... puts "\ndeckList : $deckList" puts "L) card #3 : [lindex $deckList 2]" ;# index is zero-based puts "\nparray:" parray deckArray ;# show all elements, unsorted puts "A) card #3 = $deckArray(3)" puts "\nDone." #. ====== '''Output 12''' ======none Deck of cards: AS=A♠ 2S=2♠ 3S=3♠ 4S=4♠ 5S=5♠ 6S=6♠ 7S=7♠ 8S=8♠ 9S=9♠ 10S=10♠ JS=J♠ QS=Q♠ KS=K♠ AH=A♥ 2H=2♥ 3H=3♥ 4H=4♥ 5H=5♥ 6H=6♥ 7H=7♥ 8H=8♥ 9H=9♥ 10H=10♥ JH=J♥ QH=Q♥ KH=K♥ AD=A♦ 2D=2♦ 3D=3♦ 4D=4♦ 5D=5♦ 6D=6♦ 7D=7♦ 8D=8♦ 9D=9♦ 10D=10♦ JD=J♦ QD=Q♦ KD=K♦ AC=A♣ 2C=2♣ 3C=3♣ 4C=4♣ 5C=5♣ 6C=6♣ 7C=7♣ 8C=8♣ 9C=9♣ 10C=10♣ JC=J♣ QC=Q♣ KC=K♣ deckStr : A♠2♠3♠4♠5♠6♠7♠8♠9♠10♠J♠Q♠K♠A♥2♥3♥4♥5♥6♥7♥8♥9♥10♥J♥Q♥K♥A♦2♦3♦4♦5♦6♦7♦8♦9♦10♦J♦Q♦K♦A♣2♣3♣4♣5♣6♣7♣8♣9♣10♣J♣Q♣K♣ S) card #3 : 3♠ deckList : A♠ 2♠ 3♠ 4♠ 5♠ 6♠ 7♠ 8♠ 9♠ 10♠ J♠ Q♠ K♠ A♥ 2♥ 3♥ 4♥ 5♥ 6♥ 7♥ 8♥ 9♥ 10♥ J♥ Q♥ K♥ A♦ 2♦ 3♦ 4♦ 5♦ 6♦ 7♦ 8♦ 9♦ 10♦ J♦ Q♦ K♦ A♣ 2♣ 3♣ 4♣ 5♣ 6♣ 7♣ 8♣ 9♣ 10♣ J♣ Q♣ K♣ L) card #3 : 3♠ parray: deckArray(1) = A♠ deckArray(10) = 10♠ deckArray(11) = J♠ deckArray(12) = Q♠ deckArray(13) = K♠ .. deckArray(48) = 9♣ deckArray(49) = 10♣ deckArray(5) = 5♠ deckArray(50) = J♣ deckArray(51) = Q♣ deckArray(52) = K♣ deckArray(6) = 6♠ deckArray(7) = 7♠ deckArray(8) = 8♠ deckArray(9) = 9♠ A) card #3 = 3♠ Done. ====== ---- **Program 13 - xx** ======tcl # HelloWorld013.tcl - 2015-06-24 # http://ideone.com/1t0KK7 #. ====== '''Output 13''' ======none xx ====== ---- Some ideas: * Table of primes ** as list / array * Dice-rolling ** with min/max/average * Number of days between dates ... ---- **Program 1x - xx** ======tcl # HelloWorld01x.tcl - 2015-06-24 #. ====== '''Output 1x''' ======none xx ====== ---- ---- **Remarks** This is the Alpha-version, there ''will'' be bugs, so use with caution <
> ... ---- '''See also:''' * http://wiki.tcl.tk/41210%|%ClockDemo%|% * [Whitejack] * [tcltutorial] * http://www.tcl.tk/man/tcl8.5/tutorial/tcltutorial.html * http://www.tcl.tk/man/tcl8.5/TclCmd/Tcl.htm <> Example | Tutorial