New in Tcl? Coming from another language? Read on.

This could be fun. I learned almost all of my programming with [PHP], and a little bit of [Perl]. This sheet [http://www.cs.tufts.edu/g/20/notes/php_perl.php] helped me an awful lot when I tried to learn [Perl], so a Tcl cheat sheet may be awfully useful to someone else. Feel free to add other languages.

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'''PHP:'''  file.php3

'''PERL:'''  file.cgi

'''TCL:'''  file.tcl
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'''PHP:'''  scripts in <?php..?>

'''PERL:'''  whole file is script

'''TCL:'''  whole file is script
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'''PHP:'''  can include raw HTML

'''PERL:'''  must print all output

'''TCL:'''  must print all output
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'''PHP:'''  no requirements for first line

'''PERL:'''  first line is #!/local/bin/perl  (but is that a requirement?)

'''TCL:'''  first line can be #!/local/bin/tclsh  (but that is no requirement)
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'''protections'''

'''PHP:'''  not executable file

'''PERL:'''  executable file

'''TCL:'''  What the heck? You can make almost any file executable in nix platforms!
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'''PHP:'''  chmod 644 file.php3

'''PERL:'''  chmod 755 file.cgi

'''TCL:'''  er... I don't know
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'''printing'''

'''PHP:'''  echo "stuff\n";

'''PERL:'''  print "stuff\n";

'''TCL:'''  puts stuff  '''OR'''  puts "some stuff"  '''OR''' puts {some stuff}
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'''variables'''

'''PHP:'''  All variables $var

'''PERL:'''  $var is a scalar variable.

'''TCL:'''  '''var''' or '''$var''' - more detailed explanation needed here. See [set]
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'''PHP:'''  $var always means one thing

'''PERL:'''  $var, @var, %var, var are different things!

'''TCL:'''  $var and var always means one thing (???)
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'''arrays'''

'''PHP:'''  $var = array(1,2,3);

'''PERL:'''  @var = (1,2,3);

'''TCL:'''  well, there are lists...

 set var "1 2 3"  '''OR'''  set var [ list 1 2 3 ]

and arrays...

 array set var "key1 value1 key2 value2 key3 value3"

'''PHP:'''  "numeric" arrays and "associative" arrays

'''PERL:'''  "arrays" and "hashes"

'''TCL:'''  "lists" and "arrays"


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'''PHP:'''  $var[[1]] is second element of $var

'''PERL:'''  $var[[1]] is second element of @var

'''TCL:'''  [[ lindex $var 1 ]] is second element of $var
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'''PHP:'''  count($var) is length

'''PERL:'''  scalar(@var) is length

'''TCL:'''  [[ llength $var ]] is length
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'''PHP:'''  for ($i=0; $i<count($var); $i++) echo $var[[$i]];

'''PERL:'''  foreach $thing (@var) { print $thing; }

'''TCL:'''  for { set i 0 }  {$i < [[ llength $var ]] }  { incr i }  { puts [[ lindex $var $i ]] }
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'''PHP:'''  join(":",array(1,2,3))

'''PERL:'''  join(":",(1,2,3))

'''TCL:'''  join [[ list 1 2 3 ]] :   (yeah, yeah, you can wrap the colon in quotes if you're queasy)
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'''objects'''

'''PHP:'''  associative arrays are arrays

'''PERL:'''  associative arrays are their own type

'''TCL:'''  Er... what is a "type"?  ;-)
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'''PHP:'''  $var = array(1=>"ho","hi"=>4);

'''PERL:'''  %var = (1=>"ho","hi"=>4);

'''TCL:'''  array set var "1 ho hi 4"
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'''PHP:'''  $var[['ho']] is element indexed by 'ho'

'''PERL:'''  $var{'ho'} is element of %var

'''TCL:'''  $var[['ho']] is element indexed by 'ho'  ''??? - confusing''
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'''PHP:'''  while (list($k,$v) = each $var)) {...}

'''PERL:'''  while (($k,$v) = each %var) {...}

'''TCL:'''  er...  foreach { key value } [[ array get var ]]  {...}
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'''to be continued...'''

Roy Terry, 17Jan2003 - say this looks helpful. On your next pass can you be more specific on 1) What each section is trying to
demonstrate, and 2) your questions about Tcl. "??? - confusing" doesn't give folks a good idea of what additional info you need.
One obvious correction: Tcl uses parens, not square brackets, to index arrays. Further more the single quote has absolutely no
special meaning in Tcl, it does not quote things and it will not be removed by the parser; so best to avoid it. Now I see something
else: In Tcl variables can be either an array or a string value and that's determined by usage.

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