NAME
       foreach - Iterate over all elements in one or more lists

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


DESCRIPTION
       The foreach command implements a loop where the loop vari-
       able(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 com-
       mand 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  asso-
       ciated  with  a list of loop variables (e.g., varlist1 and
       varlist2).  During each iteration of the  loop  the  vari-
       ables 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.

EXAMPLES
       The following loop uses i and j as loop variables to iter-
       ate 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 loop.


       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.



SEE ALSO
       for(n), while(n), break(n), continue(n)


KEYWORDS
       foreach, iteration, list, looping
