NAME

       foreach - Iterate over all elements in one or more lists

SYNOPSIS

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

       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.

EXAMPLES

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

KEYWORDS

       foreach, iteration, list, looping