CODEWITHSUNDEEP
tcl
soofyaan
soofyaan

Reputation: 299

Using value of members in a list as the key to another list in Tcl

I'm new to Tcl. I want to use element-value in a list as the key to another list. So if I have:

set  mainlist  { list1 list2 }  
set  list1 { val1 val2 }
set  list1 { val3 val4 }

I would like to iterate on mainlist members to get list1 and list2 members.

I tried following but it did't work:

for {set i 0} {$i < [llength $list1]} {incr i}  {

  set  mem  [lindex $list1 $i] 

  for {set j 0} {$j < [llength $mem]} {incr j} {

     puts [lindex $mem $j]

   }
}

Any solution?

Upvotes: 1

Views: 251

Answers (3)

Johannes Kuhn
Johannes Kuhn

Reputation: 15163

Well, indirect variable access. Use set for this.

your code could be:

set  mainlist  { list1 list2 }  
set  list1 { val1 val2 }
set  list2 { val3 val4 }

foreach mem $mainlist {
    foreach val [set $mem] {
        puts $val
    }
}

Why don't you use nested lists?

Edit:
You use $mem, which has the value list1 or list2 respective. But you try to access the content of the variable list1, so you have to use set varname or set $variable_with__varname.

foreach is not only quicker, it is also more clear what intention you have.
See the tcl.tk wiki for more information.

Upvotes: 2

Jerry
Jerry

Reputation: 71538

I'm not too sure either about what you're asking, but from the loops you did, it seems like you want to do something like this:

set list1 {key1 value1}
set list2 {key2 value2}
set mainlist [list $list1 $list2]

Note that you need to have the variables set before you put them in a list.

Now, if you have the key key2, to get the value value2, you can use the loops you did, made a bit differently:

set key "key2"
foreach i $mainlist {
    if {[lindex $i 0] == $key} {
         puts [lindex $i 1]
    }
}

Upvotes: 1

GIC82
GIC82

Reputation: 151

I think there is no need of using "for" command. You can use following,

 set  mainlist  { list1 list2 }  

 set list1_mem  [lindex $mainlist  0]
 foreach val1 $list1_mem {
  puts $val1
 }
 set list2_mem  [lindex $mainlist  1]
 foreach val2 $list2_mem {
   puts $val2
 }

I am using the TCL 8.4 there more optimised ways in after versions.

Upvotes: 0

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