Combining variables 1

[shussai2]

I know I have asked a similar question before but this one is a little tricky:
Given:

global chip
global reg
global reg${chip}x${reg}

What I want to do is display the contents of
reg${chip}x${reg} by looping since chip is from 1 to 2 and reg is from 0 to 31. Here is what I have:

set c 1
while {$c <= 2} {
set i 0
while {$i <= 31} {
puts $fileId &quot;R $c $i $reg${c}x${i}&quot; -----PROBLEM
incr i
}
incr c
}

 

[ulis]

1/ Tcl does only one substitution round and your code needs two rounds.
2/ It should be better you use an array.

1/ Tcl substitution
When interpreting a command, Tcl first does variables substitutions (replaces $x by its value) and embedded scripts evaluations (replaces [func] by the returned value).

  set a a
  set b b
  set ab value
  puts $a$b
-> ab

What you want is:

  puts $a$b (<- wrong syntax)
-> value    (<- wanted value)

You can obtain the wanted value with:

  puts [set $a$b]
-> value

This because Tcl translates [set $a$b] to [set ab] and obtains the desired value.

2/ Using an array
When you find yourself generating the name of a variable, it's time to see if an array is not a good solution:

  set reg(1,0) reg1,0
  set chip 1
  set reg 0
  puts $reg($chip,$reg)
-> reg1,0

A page of interest:

http://mini.net/tcl/9739

HTH

ulis