Provided by: tcl8.4-doc_8.4.20-7_all bug


       foreach - Iterate over all elements in one or more lists


       foreach varname list body
       foreach varlist1 list1 ?varlist2 list2 ...? body


       The  foreach  command implements a loop where the loop variable(s) take on values from one
       or more lists.  In the simplest case there is one loop variable, varname,  and  one  list,
       list,  that  is a list of values to assign to varname.  The body argument is a Tcl script.
       For each element of list (in order from first to last), foreach assigns  the  contents  of
       the element to varname as if the lindex command had been used to extract the element, then
       calls the Tcl interpreter to execute body.

       In the general case there can be more than one value list (e.g.,  list1  and  list2),  and
       each  value  list  can  be  associated  with  a list of loop variables (e.g., varlist1 and
       varlist2).  During each iteration of the loop the variables of each varlist  are  assigned
       consecutive  values  from  the  corresponding list.  Values in each list are used in order
       from first to last, and each value is  used  exactly  once.   The  total  number  of  loop
       iterations  is large enough to use up all the values from all the value lists.  If a value
       list does not contain enough elements for each of its loop variables  in  each  iteration,
       empty values are used for the missing elements.

       The  break  and continue statements may be invoked inside body, with the same effect as in
       the for command.  Foreach returns an empty string.


       The following loop uses i and j as loop variables to iterate over pairs of elements  of  a
       single list.  set x {} foreach {i j} {a b c d e f} {
           lappend  x  $j  $i } # The value of x is "b a d c f e" # There are 3 iterations of the

       The next loop uses i and j to iterate over two lists in parallel.  set x {} foreach i {a b
       c} j {d e f g} {
           lappend  x  $i $j } # The value of x is "a d b e c f {} g" # There are 4 iterations of
       the loop.

       The two forms are combined in the following example.  set x {} foreach i {a b c} {j k}  {d
       e f g} {
           lappend  x  $i  $j  $k  }  #  The  value  of  x is "a d e b f g c {} {}" # There are 3
       iterations of the loop.


       for(3tcl), while(3tcl), break(3tcl), continue(3tcl)


       foreach, iteration, list, looping