foreach(n)            Tcl Built-In Commands            foreach(n)



_________________________________________________________________

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

SSYYNNOOPPSSIISS
       ffoorreeaacchh _v_a_r_n_a_m_e _l_i_s_t _b_o_d_y
       ffoorreeaacchh _v_a_r_l_i_s_t_1 _l_i_s_t_1 ?_v_a_r_l_i_s_t_2 _l_i_s_t_2 _._._.? _b_o_d_y
_________________________________________________________________


DDEESSCCRRIIPPTTIIOONN
       The ffoorreeaacchh 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, _v_a_r_n_a_m_e, and one
       list, _l_i_s_t, that is a list of values to assign to _v_a_r_n_a_m_e.
       The  _b_o_d_y  argument  is a Tcl script.  For each element of
       _l_i_s_t (in order from first to last),  ffoorreeaacchh  assigns  the
       contents  of  the element to _v_a_r_n_a_m_e as if the lliinnddeexx com­
       mand had been used to extract the element, then calls  the
       Tcl interpreter to execute _b_o_d_y.

       In  the general case there can be more than one value list
       (e.g., _l_i_s_t_1 and _l_i_s_t_2), and each value list can be  asso­
       ciated  with  a list of loop variables (e.g., _v_a_r_l_i_s_t_1 and
       _v_a_r_l_i_s_t_2).  During each iteration of the  loop  the  vari­
       ables of each _v_a_r_l_i_s_t are assigned consecutive values from
       the corresponding _l_i_s_t.  Values in each _l_i_s_t 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 bbrreeaakk and ccoonnttiinnuuee statements may  be  invoked  inside
       _b_o_d_y, with the same effect as in the ffoorr command.  FFoorreeaacchh
       returns an empty string.

EEXXAAMMPPLLEESS
       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.



SSEEEE AALLSSOO
       for(n), while(n), break(n), continue(n)


KKEEYYWWOORRDDSS
       foreach, iteration, list, looping



Tcl                                                    foreach(n)