Version 3 of HelloWorld

if 0 {

• Introduction
• Program 1
• Program 2
• Output
• Remarks

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 quite simple , so an amount of code to fill about one printed page should be enough.

Basic features to cover:

• Comments
• Output / format
• Numeric variables
• String variables / quoting
• simple calculations / incr / expr
• if / then / else
• for - loop, maybe while-loop
• foreach
• proc / return

Advanced features (to include if space permits):

• input / checking the input
• catch
• string-operations (e.g. find/extract/replace char in a string, append, delete/split ...)
• data-structures: array / list / dict
• file-operations

...

Even more advanced features (to be left out, for a later lesson):

• upvar / uplevel
• namespaces
• unknown

...

Things to be aware of:

• comments are commands, so quotes and braces inside need to be balanced
• 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

  # HelloWorld001.tcl - 2015-06-13 - http://wiki.tcl.tk/41268
  # Output string to terminal:

  puts "Hello, World!"

  ### EOF ###

Program 2

 # HelloWorld002.tcl - MiHa - 2015-06-13
 # http://wiki.tcl.tk/41268

 # http://ideone.com/xxx
  puts "Demo:"
  set i 0
  foreach s { Hello , world ! }  { incr i; puts "$i $s" }
 ### EOF ###

Output

Demo:
1 Hello
2 ,
3 World
4 !

Remarks

This is the Alpha-version, there will be bugs, so use with caution
...

See also:

• ClockDemo
• ...