https://wiki.tcl-lang.org/_edit/BUG+%2D+%27string+length%27+count+also+NON+visible+chars#
**update 7 mar 2024**

the '''CORE''' problem is ''not'' just the `string length` the '''CORE''' problem is the representation of the string in `TCL` 
(and all other programming languages as well)

let's start simple: the problem is just the same als the ''multibyte chars problem'' raised up ~30 years ago.

→ at the beginning it was only `ascii` and a string was `char*` after a while they figure out that a languages with ''more''
chars than plain `ascii`. It took ~20 years to implement `utf8` and finally `utf16`. 

`TCL` uses `utf8` as script-encoding and `utf16` internal as string representation because s ''string'' is only useful if ''index''
operations can be performt like: `string index $str 0` and `utf16` is '''index-able''' and `utf8` not


**original problem**
Hi,

I use a library to format and print a ''debugging-message'' which also uses the ''linux-terminal-color-code''.

The '''CORE''' problem is that `string length ..` is used to format the message and finally add some additional information etc
BUT the `string length ..` count the NON-visible color-code as well as visible chars that result in a MISS-format string

example: (color is not visible in this thread !! - but all is "green")

 -> outTXT<multi-line>
 ->   |   |DEBUG[1]: aa   -> LIST                                     |  <- count color codes
 ->   |   |DEBUG[1]:      ->   | a1                   : 111           |  <- count color codes
 ->   |   |DEBUG[1]:      ->   | a2                   : 222           |  <- count color codes
 ->   |   |DEBUG[1]:      ->   | a3                   : 333 |


a color-code is something like

  ## ------------------------------------------------------------------------
  ## DEBUG helper
  ##  Black        0;30     Dark Gray     1;30
  ##  Red          0;31     Light Red     1;31
  ##  Green        0;32     Light Green   1;32
  ##  Brown/Orange 0;33     Yellow        1;33
  ##  Blue         0;34     Light Blue    1;34
  ##  Purple       0;35     Light Purple  1;35
  ##  Cyan         0;36     Light Cyan    1;36
  ##  Light Gray   0;37     White         1;37
  ##
  ##  8bit (256) colors: https://stackoverflow.com/questions/4842424/list-of-ansi-color-escape-sequences
  variable CL_COLOR
  set  CL_COLOR(red)        "\[1;31m"
  set  CL_COLOR(green)      "\[1;32m"
  set  CL_COLOR(yellow)     "\[1;33m"
  set  CL_COLOR(blue)       "\[1;34m"
  set  CL_COLOR(purple)     "\[38;5;206m"
  set  CL_COLOR(cyan)       "\[1;36m"
  set  CL_COLOR(lightcyan)  "\[38;5;51m"
  set  CL_COLOR(white)      "\[1;37m"
  set  CL_COLOR(grey)       "\[38;5;254m"
  set  CL_COLOR(orange)     "\[38;5;202m"
  set  CL_COLOR(no)         ""
  variable  CL_RESET        "\[0;m"


code:

  set tstmsg  "$lib_debug::CL_COLOR(red)123$lib_debug::CL_RESET"
  puts "$tstmsg"
  puts [string length $tstmsg]

result:

  123        (the color of "123" is red)
  15         (this should be 3)


there is something MISSING in TCL and this is the `string length ...` only count the !! VISIBLE !! chars


mfg ao

----
[GWL] The definition of what is a !! VISIBLE !! chars depends on the device that is displaying the string.  This is not something TCL is missing.  This is very application specific.